Programs & Examples On #Common table expression

A Common Table Expression (CTE) is a temporary result set that is defined within the execution scope of a single SELECT, INSERT, UPDATE, DELETE, or CREATE VIEW statement.

SQL Server CTE and recursion example

    --DROP TABLE #Employee
    CREATE TABLE #Employee(EmpId BIGINT IDENTITY,EmpName VARCHAR(25),Designation VARCHAR(25),ManagerID BIGINT)

    INSERT INTO #Employee VALUES('M11M','Manager',NULL)
    INSERT INTO #Employee VALUES('P11P','Manager',NULL)

    INSERT INTO #Employee VALUES('AA','Clerk',1)
    INSERT INTO #Employee VALUES('AB','Assistant',1)
    INSERT INTO #Employee VALUES('ZC','Supervisor',2)
    INSERT INTO #Employee VALUES('ZD','Security',2)


    SELECT * FROM #Employee (NOLOCK)

    ;
    WITH Emp_CTE 
    AS
    (
        SELECT EmpId,EmpName,Designation, ManagerID
              ,CASE WHEN ManagerID IS NULL THEN EmpId ELSE ManagerID END ManagerID_N
        FROM #Employee  
    )
    select EmpId,EmpName,Designation, ManagerID
    FROM Emp_CTE
    order BY ManagerID_N, EmpId

How to create Temp table with SELECT * INTO tempTable FROM CTE Query

Select      Eventname, 
            count(Eventname) as 'Counts'
INTO        #TEMPTABLE                                                                                
FROM        tblevent
where       Eventname like 'A%'
Group by    Eventname
order by    count(Eventname)

Here by using the into clause the table is directly created

Can you create nested WITH clauses for Common Table Expressions?

Nested 'With' is not supported, but you can always use the second With as a subquery, for example:

WITH A AS (
                --WITH B AS ( SELECT COUNT(1) AS _CT FROM C ) SELECT CASE _CT WHEN 1 THEN 1 ELSE 0 END FROM B --doesn't work
                SELECT CASE WHEN count = 1 THEN 1 ELSE 0 END AS CT FROM (SELECT COUNT(1) AS count FROM dual)
                union all
                select 100 AS CT from dual
           )
              select CT FROM A

How do you use the "WITH" clause in MySQL?

MySQL prior to version 8.0 doesn't support the WITH clause (CTE in SQL Server parlance; Subquery Factoring in Oracle), so you are left with using:

  • TEMPORARY tables
  • DERIVED tables
  • inline views (effectively what the WITH clause represents - they are interchangeable)

The request for the feature dates back to 2006.

As mentioned, you provided a poor example - there's no need to perform a subselect if you aren't altering the output of the columns in any way:

  SELECT * 
    FROM ARTICLE t
    JOIN USERINFO ui ON ui.user_userid = t.article_ownerid
    JOIN CATEGORY c ON c.catid =  t.article_categoryid
   WHERE t.published_ind = 0
ORDER BY t.article_date DESC 
   LIMIT 1, 3

Here's a better example:

SELECT t.name,
       t.num
  FROM TABLE t
  JOIN (SELECT c.id
               COUNT(*) 'num'
          FROM TABLE c
         WHERE c.column = 'a'
      GROUP BY c.id) ta ON ta.id = t.id

The maximum recursion 100 has been exhausted before statement completion

Specify the maxrecursion option at the end of the query:

...
from EmployeeTree
option (maxrecursion 0)

That allows you to specify how often the CTE can recurse before generating an error. Maxrecursion 0 allows infinite recursion.

MySQL "WITH" clause

MariaDB is now supporting WITH. MySQL for now is not. https://mariadb.com/kb/en/mariadb/with/

Is there a performance difference between CTE , Sub-Query, Temporary Table or Table Variable?

#temp is materalized and CTE is not.

CTE is just syntax so in theory it is just a subquery. It is executed. #temp is materialized. So an expensive CTE in a join that is execute many times may be better in a #temp. On the other side if it is an easy evaluation that is not executed but a few times then not worth the overhead of #temp.

The are some people on SO that don't like table variable but I like them as the are materialized and faster to create than #temp. There are times when the query optimizer does better with a #temp compared to a table variable.

The ability to create a PK on a #temp or table variable gives the query optimizer more information than a CTE (as you cannot declare a PK on a CTE).

Which are more performant, CTE or temporary tables?

One use where I found CTE's excelled performance wise was where I needed to join a relatively complex Query on to a few tables which had a few million rows each.

I used the CTE to first select the subset based of the indexed columns to first cut these tables down to a few thousand relevant rows each and then joined the CTE to my main query. This exponentially reduced the runtime of my query.

Whilst results for the CTE are not cached and table variables might have been a better choice I really just wanted to try them out and found the fit the above scenario.

Combining INSERT INTO and WITH/CTE

The WITH clause for Common Table Expressions go at the top.

Wrapping every insert in a CTE has the benefit of visually segregating the query logic from the column mapping.

Spot the mistake:

WITH _INSERT_ AS (
  SELECT
    [BatchID]      = blah
   ,[APartyNo]     = blahblah
   ,[SourceRowID]  = blahblahblah
  FROM Table1 AS t1
)
INSERT Table2
      ([BatchID], [SourceRowID], [APartyNo])
SELECT [BatchID], [APartyNo], [SourceRowID]   
FROM _INSERT_

Same mistake:

INSERT Table2 (
  [BatchID]
 ,[SourceRowID]
 ,[APartyNo]
)
SELECT
  [BatchID]      = blah
 ,[APartyNo]     = blahblah
 ,[SourceRowID]  = blahblahblah
FROM Table1 AS t1

A few lines of boilerplate make it extremely easy to verify the code inserts the right number of columns in the right order, even with a very large number of columns. Your future self will thank you later.

Update records in table from CTE

WITH CTE_DocTotal (DocTotal, InvoiceNumber)
AS
(
    SELECT  InvoiceNumber,
            SUM(Sale + VAT) AS DocTotal
    FROM    PEDI_InvoiceDetail
    GROUP BY InvoiceNumber
)    
UPDATE PEDI_InvoiceDetail
SET PEDI_InvoiceDetail.DocTotal = CTE_DocTotal.DocTotal
FROM CTE_DocTotal
INNER JOIN PEDI_InvoiceDetail ON ...

getting "No column was specified for column 2 of 'd'" in sql server cte?

[edit]

I tried to rewrite your query, but even yours will work once you associate aliases to the aggregate columns in the query that defines 'd'.


I think you are looking for the following:

First one:

select 
    c.duration, 
    c.totalbookings, 
    d.bkdqty 
from
    (select 
               month(bookingdate) as duration, 
               count(*) as totalbookings 
           from 
               entbookings
           group by month(bookingdate)
    ) AS c 
    inner join 
    (SELECT 
               duration, 
               sum(totalitems) 'bkdqty'
           FROM 
               [DrySoftBranch].[dbo].[mnthItemWiseTotalQty] ('1') AS BkdQty
           group by duration
    ) AS d 
    on c.duration = d.duration

Second one:

select 
    c.duration, 
    c.totalbookings, 
    d.bkdqty 
from
    (select 
               month(bookingdate) as duration, 
               count(*) as totalbookings 
           from 
               entbookings
           group by month(bookingdate)
    ) AS c 
    inner join 
    (select 
               month(clothdeliverydate) 'clothdeliverydatemonth', 
               SUM(CONVERT(INT, deliveredqty)) 'bkdqty'
           FROM 
               barcodetable
           where 
               month(clothdeliverydate) is not null
               group by month(clothdeliverydate)
    ) AS d 
    on c.duration = d.duration

Keeping it simple and how to do multiple CTE in a query

You certainly are able to have multiple CTEs in a single query expression. You just need to separate them with a comma. Here is an example. In the example below, there are two CTEs. One is named CategoryAndNumberOfProducts and the second is named ProductsOverTenDollars.

WITH CategoryAndNumberOfProducts (CategoryID, CategoryName, NumberOfProducts) AS
(
   SELECT
      CategoryID,
      CategoryName,
      (SELECT COUNT(1) FROM Products p
       WHERE p.CategoryID = c.CategoryID) as NumberOfProducts
   FROM Categories c
),

ProductsOverTenDollars (ProductID, CategoryID, ProductName, UnitPrice) AS
(
   SELECT
      ProductID,
      CategoryID,
      ProductName,
      UnitPrice
   FROM Products p
   WHERE UnitPrice > 10.0
)

SELECT c.CategoryName, c.NumberOfProducts,
      p.ProductName, p.UnitPrice
FROM ProductsOverTenDollars p
   INNER JOIN CategoryAndNumberOfProducts c ON
      p.CategoryID = c.CategoryID
ORDER BY ProductName

When to use Common Table Expression (CTE)

One point not pointed out yet, is the speed. I know it's an old answered question, but I think this deserves direct comment/answer:

They would seem to be redundant as the same can be done with derived tables

When I used CTE the very first time I was absolutely stunned by it's speed. It was a case like from a textbook, very suitable for CTE, but in all ocurences I ever used CTE, there was a significant speed gain. My first query was complex with derived tables, taking long minutes to execute. With CTE it took fractions of seconds and left me shocked, that it is even possible.

"Large data" workflows using pandas

I'd like to point out the Vaex package.

Vaex is a python library for lazy Out-of-Core DataFrames (similar to Pandas), to visualize and explore big tabular datasets. It can calculate statistics such as mean, sum, count, standard deviation etc, on an N-dimensional grid up to a billion (109) objects/rows per second. Visualization is done using histograms, density plots and 3d volume rendering, allowing interactive exploration of big data. Vaex uses memory mapping, zero memory copy policy and lazy computations for best performance (no memory wasted).

Have a look at the documentation: https://vaex.readthedocs.io/en/latest/ The API is very close to the API of pandas.

NULL or BLANK fields (ORACLE)

COUNT(expresion) returns the count of of rows where expresion is not null. So SELECT COUNT (COL_NAME) FROM TABLE WHERE COL_NAME IS NULL will return 0, because you are only counting col_name where col_name is null, and a count of nothing but nulls is zero. COUNT(*) will return the number of rows of the query:

SELECT COUNT (*) FROM TABLE WHERE COL_NAME IS NULL

The other two queries are probably not returning any rows, since they are trying to match against strings with one blank character, and your dump query indicates that the column is actually holding nulls.

If you have rows with variable strings of space characters that you want included in the count, use:

SELECT COUNT (*) FROM TABLE WHERE trim(COL_NAME) IS NULL

trim(COL_NAME) will remove beginning and ending spaces. If the string is nothing but spaces, then the string becomes '' (empty string), which is equivalent to null in Oracle.

How to make execution pause, sleep, wait for X seconds in R?

See help(Sys.sleep).

For example, from ?Sys.sleep

testit <- function(x)
{
    p1 <- proc.time()
    Sys.sleep(x)
    proc.time() - p1 # The cpu usage should be negligible
}
testit(3.7)

Yielding

> testit(3.7)
   user  system elapsed 
  0.000   0.000   3.704 

The create-react-app imports restriction outside of src directory

If you only need to import a single file, such as README.md or package.json, then this can be explicitly added to ModuleScopePlugin()

config/paths.js

const resolveApp = relativePath => path.resolve(appDirectory, relativePath);
module.exports = {
  appPackageJson: resolveApp('package.json'),
  appReadmeMD:    resolveApp('README.md'),
};

config/webpack.config.dev.js + config/webpack.config.prod.js

module.exports = {
  resolve: {
    plugins: [
      // Prevents users from importing files from outside of src/ (or node_modules/).
      // This often causes confusion because we only process files within src/ with babel.
      // To fix this, we prevent you from importing files out of src/ -- if you'd like to,
      // please link the files into your node_modules/ and let module-resolution kick in.
      // Make sure your source files are compiled, as they will not be processed in any way.
      new ModuleScopePlugin(paths.appSrc, [
          paths.appPackageJson,
          paths.appReadmeMD         // README.md lives outside of ./src/ so needs to be explicitly included in ModuleScopePlugin()
      ]),
    ]
  }
}

How do I get the last word in each line with bash

You can do it easily with grep:

grep -oE '[^ ]+$' file

(-E use extended regex; -o output only the matched text instead of the full line)

Python import csv to list

Next is a piece of code which uses csv module but extracts file.csv contents to a list of dicts using the first line which is a header of csv table

import csv
def csv2dicts(filename):
  with open(filename, 'rb') as f:
    reader = csv.reader(f)
    lines = list(reader)
    if len(lines) < 2: return None
    names = lines[0]
    if len(names) < 1: return None
    dicts = []
    for values in lines[1:]:
      if len(values) != len(names): return None
      d = {}
      for i,_ in enumerate(names):
        d[names[i]] = values[i]
      dicts.append(d)
    return dicts
  return None

if __name__ == '__main__':
  your_list = csv2dicts('file.csv')
  print your_list

In Django, how do I check if a user is in a certain group?

In one line:

'Groupname' in user.groups.values_list('name', flat=True)

This evaluates to either True or False.

How to define the css :hover state in a jQuery selector?

Well, you can't add styling using pseudo selectors like :hover, :after, :nth-child, or anything like that using jQuery.

If you want to add a CSS rule like that you have to create a <style> element and add that :hover rule to it just like you would in CSS. Then you would have to add that <style> element to the page.

Using the .hover function seems to be more appropriate if you can't just add the css to a stylesheet, but if you insist you can do:

$('head').append('<style>.myclass:hover div {background-color : red;}</style>')

If you want to read more on adding CSS with javascript you can check out one of David Walsh's Blog posts.

jquery - How to determine if a div changes its height or any css attribute?

Please don't use techniques described in other answers here. They are either not working with css3 animations size changes, floating layout changes or changes that don't come from jQuery land. You can use a resize-detector, a event-based approach, that doesn't waste your CPU time.

https://github.com/marcj/css-element-queries

It contains a ResizeSensor class you can use for that purpose.

new ResizeSensor(jQuery('#mainContent'), function(){ 
    console.log('main content dimension changed');
});

Disclaimer: I wrote this library

How do I convert a org.w3c.dom.Document object to a String?

A Scala version based on Zaz's answer.

  case class DocumentEx(document: Document) {
    def toXmlString(pretty: Boolean = false):Try[String] = {
      getStringFromDocument(document, pretty)
    }
  }

  implicit def documentToDocumentEx(document: Document):DocumentEx = {
    DocumentEx(document)
  }

  def getStringFromDocument(doc: Document, pretty:Boolean): Try[String] = {
    try
    {
      val domSource= new DOMSource(doc)
      val writer = new StringWriter()
      val result = new StreamResult(writer)
      val tf = TransformerFactory.newInstance()
      val transformer = tf.newTransformer()
      if (pretty)
        transformer.setOutputProperty(OutputKeys.INDENT, "yes")
      transformer.transform(domSource, result)
      Success(writer.toString);
    }
    catch {
      case ex: TransformerException =>
        Failure(ex)
    }
  }

With that, you can do either doc.toXmlString() or call the getStringFromDocument(doc) function.

Java 8 stream's .min() and .max(): why does this compile?

Apart from the information given by David M. Lloyd one could add that the mechanism that allows this is called target typing.

The idea is that the type the compiler assigns to a lambda expressions or a method references does not depend only on the expression itself, but also on where it is used.

The target of an expression is the variable to which its result is assigned or the parameter to which its result is passed.

Lambda expressions and method references are assigned a type which matches the type of their target, if such a type can be found.

See the Type Inference section in the Java Tutorial for more information.

How to convert a String to JsonObject using gson library

Note that as of Gson 2.8.6, instance method JsonParser.parse has been deprecated and replaced by static method JsonParser.parseString:

JsonObject jsonObject = JsonParser.parseString(json).getAsJsonObject();

PHP - Insert date into mysql

$date=$year."-".$month."-".$day; 
$new_date=date('Y-m-d', strtotime($dob)); 
$status=0;  
$insert_date = date("Y-m-d H:i:s");  
$latest_insert_id=0; 

$insertSql="insert into participationDetail (formId,name,city,emailId,dob,mobile,status,social_media1,social_media2,visa_status,tnc_status,data,gender,insertDate)values('".$formid."','".$name."','".$city."','".$email."','".$new_date."','".$mobile."','".$status."','".$link1."','".$link2."','".$visa_check."','".$tnc_check."','".json_encode($detail_arr,JSON_HEX_APOS)."','".$gender."','".$insert_date."')";

Hard reset of a single file

Reset to head:

To hard reset a single file to HEAD:

git checkout @ -- myfile.ext

Note that @ is short for HEAD. An older version of git may not support the short form.

Reset to index:

To hard reset a single file to the index, assuming the index is non-empty, otherwise to HEAD:

git checkout -- myfile.ext

The point is that to be safe, you don't want to leave out @ or HEAD from the command unless you specifically mean to reset to the index only.

How do I set the eclipse.ini -vm option?

There is a wiki page here.

There are two ways the JVM can be started: by forking it in a separate process from the Eclipse launcher, or by loading it in-process using the JNI invocation API.

If you specify -vm with a path to the actual java(w).exe, then the JVM will be forked in a separate process. You can also specify -vm with a path to the jvm.dll so that the JVM is loaded in the same process:

-vm
D:/work/Java/jdk1.6.0_13/jre/bin/client/jvm.dll

You can also specify the path to the jre/bin folder itself.

Note also, the general format of the eclipse.ini is each argument on a separate line. It won't work if you put the "-vm" and the path on the same line.

Best way to use PHP to encrypt and decrypt passwords?

One thing you should be very aware of when dealing with encryption:

Trying to be clever and inventing your own thing usually will leave you with something insecure.

You'd probably be best off using one of the cryptography extensions that come with PHP.

Deep cloning objects

  1. Basically you need to implement ICloneable interface and then realize object structure copying.
  2. If it's deep copy of all members, you need to insure (not relating on solution you choose) that all children are clonable as well.
  3. Sometimes you need to be aware of some restriction during this process, for example if you copying the ORM objects most of frameworks allow only one object attached to the session and you MUST NOT make clones of this object, or if it's possible you need to care about session attaching of these objects.

Cheers.

How to center cards in bootstrap 4?

Update 2018

There is no need for extra CSS, and there are multiple centering methods in Bootstrap 4:

  • text-center for center display:inline elements
  • mx-auto for centering display:block elements inside display:flex (d-flex)
  • offset-* or mx-auto can be used to center grid columns
  • or justify-content-center on row to center grid columns

mx-auto (auto x-axis margins) will center inside display:flex elements that have a defined width, (%, vw, px, etc..). Flexbox is used by default on grid columns, so there are also various centering methods.

In your case, you can simply mx-auto to the cards.

Environment variable to control java.io.tmpdir?

Hmmm -- since this is handled by the JVM, I delved into the OpenJDK VM source code a little bit, thinking that maybe what's done by OpenJDK mimics what's done by Java 6 and prior. It isn't reassuring that there's a way to do this other than on Windows.

On Windows, OpenJDK's get_temp_directory() function makes a Win32 API call to GetTempPath(); this is how on Windows, Java reflects the value of the TMP environment variable.

On Linux and Solaris, the same get_temp_directory() functions return a static value of /tmp/.

I don't know if the actual JDK6 follows these exact conventions, but by the behavior on each of the listed platforms, it seems like they do.

Comparing two branches in Git?

git diff branch_1..branch_2

That will produce the diff between the tips of the two branches. If you'd prefer to find the diff from their common ancestor to test, you can use three dots instead of two:

git diff branch_1...branch_2

Round number to nearest integer

You can also use numpy assuming if you are using python3.x here is an example

import numpy as np
x = 2.3
print(np.rint(x))
>>> 2.0

Why would someone use WHERE 1=1 AND <conditions> in a SQL clause?

I found usefull this pattern when I'm testing or doublechecking things on the database, so I can comment very quickly other conditions:

CREATE VIEW vTest AS
SELECT FROM Table WHERE 1=1 
AND Table.Field=Value
AND Table.IsValid=true

turns into:

CREATE VIEW vTest AS
SELECT FROM Table WHERE 1=1 
--AND Table.Field=Value
--AND Table.IsValid=true

Automatic confirmation of deletion in powershell

Remove-Item .\foldertodelete -Force -Recurse

Android Error [Attempt to invoke virtual method 'void android.app.ActionBar' on a null object reference]

When use AppCompatActivity must call

Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);

Before getSupportActionBar()

public class PageActivity extends AppCompatActivity {
     @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_item);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        this.getSupportActionBar().setDisplayHomeAsUpEnabled(false);

    }
}

Best way to update data with a RecyclerView adapter

Found following solution working for my similar problem:

private ExtendedHashMap mData = new ExtendedHashMap();
private  String[] mKeys;

public void setNewData(ExtendedHashMap data) {
    mData.putAll(data);
    mKeys = data.keySet().toArray(new String[data.size()]);
    notifyDataSetChanged();
}

Using the clear-command

mData.clear()

is not nessescary

Create Hyperlink in Slack

I know you wanted only a hypertext link, but if you copy & paste a link address into Slack that does work very nicely. i.e. if referring to VersionOne ticket number (V1 mouseover the ticket window to open the mouseover window, then right click on the ticket number for the option to "copy link address", then in Slack paste. It'll paste the full ticket URL but then it shows a nice summary of the ticket number and name and you can click it to go right into the ticket.)

What does "select count(1) from table_name" on any database tables mean?

There is no difference.

COUNT(1) is basically just counting a constant value 1 column for each row. As other users here have said, it's the same as COUNT(0) or COUNT(42). Any non-NULL value will suffice.

http://asktom.oracle.com/pls/asktom/f?p=100:11:2603224624843292::::P11_QUESTION_ID:1156151916789

The Oracle optimizer did apparently use to have bugs in it, which caused the count to be affected by which column you picked and whether it was in an index, so the COUNT(1) convention came into being.

How can I generate Unix timestamps?

In Haskell...

To get it back as a POSIXTime type:

import Data.Time.Clock.POSIX
getPOSIXTime

As an integer:

import Data.Time.Clock.POSIX
round `fmap` getPOSIXTime

Facebook Graph API : get larger pictures in one request

You can size it as follows.

Use:

https://graph.facebook.com/USER_ID?fields=picture.type(large)

For details: https://developers.facebook.com/docs/graph-api/reference/user/picture/

Find CRLF in Notepad++

In 2013, v6.13 or later, use:

Menu Edit ? EOL Conversion ? Windows Format.

What is a software framework?

A lot of good answers already, but let me see if I can give you another viewpoint.

Simplifying things by quite a bit, you can view a framework as an application that is complete except for the actual functionality. You plug in the functionality and PRESTO! you have an application.

Consider, say, a GUI framework. The framework contains everything you need to make an application. Indeed you can often trivially make a minimal application with very few lines of source that does absolutely nothing -- but it does give you window management, sub-window management, menus, button bars, etc. That's the framework side of things. By adding your application functionality and "plugging it in" to the right places in the framework you turn this empty app that does nothing more than window management, etc. into a real, full-blown application.

There are similar types of frameworks for web apps, for server-side apps, etc. In each case the framework provides the bulk of the tedious, repetitive code (hopefully) while you provide the actual problem domain functionality. (This is the ideal. In reality, of course, the success of the framework is highly variable.)

I stress again that this is the simplified view of what a framework is. I'm not using scary terms like "Inversion of Control" and the like although most frameworks have such scary concepts built-in. Since you're a beginner, I thought I'd spare you the jargon and go with an easy simile.

When should an Excel VBA variable be killed or set to Nothing?

VBA uses a garbage collector which is implemented by reference counting.

There can be multiple references to a given object (for example, Dim aw = ActiveWorkbook creates a new reference to Active Workbook), so the garbage collector only cleans up an object when it is clear that there are no other references. Setting to Nothing is an explicit way of decrementing the reference count. The count is implicitly decremented when you exit scope.

Strictly speaking, in modern Excel versions (2010+) setting to Nothing isn't necessary, but there were issues with older versions of Excel (for which the workaround was to explicitly set)

java.lang.OutOfMemoryError: bitmap size exceeds VM budget - Android

Well I've tried everything I found on the internet and none of them worked. Calling System.gc() only drags down the speed of app. Recycling bitmaps in onDestroy didn't work for me too.

The only thing that works now is to have a static list of all the bitmap so that the bitmaps survive after a restart. And just use the saved bitmaps instead of creating new ones every time the activity if restarted.

In my case the code looks like this:

private static BitmapDrawable currentBGDrawable;

if (new File(uriString).exists()) {
    if (!uriString.equals(currentBGUri)) {
        freeBackground();
        bg = BitmapFactory.decodeFile(uriString);

        currentBGUri = uriString;
        bgDrawable = new BitmapDrawable(bg);
        currentBGDrawable = bgDrawable;
    } else {
        bgDrawable = currentBGDrawable;
    }
}

Rollback one specific migration in Laravel

Migrate tables one by one.

Change the batch number of the migration you want to rollback to the highest.

Run migrate:rollback.

May not be the most comfortable way to deal with larger projects.

Post to another page within a PHP script

index.php

$url = 'http://[host]/test.php';
$json = json_encode(['name' => 'Jhonn', 'phone' => '128000000000']);

$options = ['http' => [
    'method' => 'POST',
    'header' => 'Content-type:application/json',
    'content' => $json
]];

$context = stream_context_create($options);
$response = file_get_contents($url, false, $context);

test.php

$raw = file_get_contents('php://input');
$data = json_decode($raw, true);
echo $data['name']; // Jhonn

Using Ansible set_fact to create a dictionary from register results

Thank you Phil for your solution; in case someone ever gets in the same situation as me, here is a (more complex) variant:

---
# this is just to avoid a call to |default on each iteration
- set_fact:
    postconf_d: {}

- name: 'get postfix default configuration'
  command: 'postconf -d'
  register: command

# the answer of the command give a list of lines such as:
# "key = value" or "key =" when the value is null
- name: 'set postfix default configuration as fact'
  set_fact:
    postconf_d: >
      {{
        postconf_d |
        combine(
          dict([ item.partition('=')[::2]|map('trim') ])
        )
  with_items: command.stdout_lines

This will give the following output (stripped for the example):

"postconf_d": {
    "alias_database": "hash:/etc/aliases", 
    "alias_maps": "hash:/etc/aliases, nis:mail.aliases",
    "allow_min_user": "no", 
    "allow_percent_hack": "yes"
}

Going even further, parse the lists in the 'value':

- name: 'set postfix default configuration as fact'
  set_fact:
    postconf_d: >-
      {% set key, val = item.partition('=')[::2]|map('trim') -%}
      {% if ',' in val -%}
        {% set val = val.split(',')|map('trim')|list -%}
      {% endif -%}
      {{ postfix_default_main_cf | combine({key: val}) }}
  with_items: command.stdout_lines
...
"postconf_d": {
    "alias_database": "hash:/etc/aliases", 
    "alias_maps": [
        "hash:/etc/aliases", 
        "nis:mail.aliases"
    ], 
    "allow_min_user": "no", 
    "allow_percent_hack": "yes"
}

A few things to notice:

  • in this case it's needed to "trim" everything (using the >- in YAML and -%} in Jinja), otherwise you'll get an error like:

    FAILED! => {"failed": true, "msg": "|combine expects dictionaries, got u\"  {u'...
    
  • obviously the {% if .. is far from bullet-proof

  • in the postfix case, val.split(',')|map('trim')|list could have been simplified to val.split(', '), but I wanted to point out the fact you will need to |list otherwise you'll get an error like:

    "|combine expects dictionaries, got u\"{u'...': <generator object do_map at ...
    

Hope this can help.

Python regular expressions return true/false

Ignacio Vazquez-Abrams is correct. But to elaborate, re.match() will return either None, which evaluates to False, or a match object, which will always be True as he said. Only if you want information about the part(s) that matched your regular expression do you need to check out the contents of the match object.

Float vs Decimal in ActiveRecord

In Rails 4.1.0, I have faced problem with saving latitude and longitude to MySql database. It can't save large fraction number with float data type. And I change the data type to decimal and working for me.

  def change
    change_column :cities, :latitude, :decimal, :precision => 15, :scale => 13
    change_column :cities, :longitude, :decimal, :precision => 15, :scale => 13
  end

In Python script, how do I set PYTHONPATH?

You don't set PYTHONPATH, you add entries to sys.path. It's a list of directories that should be searched for Python packages, so you can just append your directories to that list.

sys.path.append('/path/to/whatever')

In fact, sys.path is initialized by splitting the value of PYTHONPATH on the path separator character (: on Linux-like systems, ; on Windows).

You can also add directories using site.addsitedir, and that method will also take into account .pth files existing within the directories you pass. (That would not be the case with directories you specify in PYTHONPATH.)

Moving Average Pandas

In case you are calculating more than one moving average:

for i in range(2,10):
   df['MA{}'.format(i)] = df.rolling(window=i).mean()

Then you can do an aggregate average of all the MA

df[[f for f in list(df) if "MA" in f]].mean(axis=1)

css transition opacity fade background

http://jsfiddle.net/6xJQq/13/

.container {
    display: inline-block;
    padding: 5px; /*included padding to see background when img apacity is 100%*/
    background-color: black;
    opacity: 1;
}

.container:hover {
    background-color: red;
}

img {
    opacity: 1;
}

img:hover {
    opacity: 0.7;
}

.transition {
    transition: all .25s ease-in-out;
    -moz-transition: all .25s ease-in-out;
    -webkit-transition: all .25s  ease-in-out;
}

How do you use MySQL's source command to import large files in windows

Don't use "source", it's designed to run a small number of sql queries and display the output, not to import large databases.

I use Wamp Developer (not XAMPP) but it should be the same.

What you want to do is use the MySQL Client to do the work for you.

  1. Make sure MySQL is running.
  2. Create your database via phpMyAdmin or the MySQL shell.
  3. Then, run cmd.exe, and change to the directory your sql file is located in.
  4. Execute: mysql -u root -p database_name_here < dump_file_name_here.sql
  5. Substitute in your database name and dump file name.
  6. Enter your MySQL root account password when prompted (if no password set, remove the "-p" switch).

This assumes that mysql.exe can be located via the environmental path, and that sql file is located in the directory you are running this from. Otherwise, use full paths.

(.text+0x20): undefined reference to `main' and undefined reference to function

This rule

main: producer.o consumer.o AddRemove.o
   $(COMPILER) -pthread $(CCFLAGS) -o producer.o consumer.o AddRemove.o

is wrong. It says to create a file named producer.o (with -o producer.o), but you want to create a file named main. Please excuse the shouting, but ALWAYS USE $@ TO REFERENCE THE TARGET:

main: producer.o consumer.o AddRemove.o
   $(COMPILER) -pthread $(CCFLAGS) -o $@ producer.o consumer.o AddRemove.o

As Shahbaz rightly points out, the gmake professionals would also use $^ which expands to all the prerequisites in the rule. In general, if you find yourself repeating a string or name, you're doing it wrong and should use a variable, whether one of the built-ins or one you create.

main: producer.o consumer.o AddRemove.o
   $(COMPILER) -pthread $(CCFLAGS) -o $@ $^

Python speed testing - Time Difference - milliseconds

Arrow: Better dates & times for Python

import arrow
start_time = arrow.utcnow()
end_time = arrow.utcnow()
(end_time - start_time).total_seconds()  # senconds
(end_time - start_time).total_seconds() * 1000  # milliseconds

PHP random string generator

If you are using this random string in a place where a user might see it or use it (eg as a password generator, you might want to limit the set of characters used to exclude vowels. That way you will not accidentally generate bad words and offend someone. Don't laugh it happens.

Using variables inside a bash heredoc

As a late corolloary to the earlier answers here, you probably end up in situations where you want some but not all variables to be interpolated. You can solve that by using backslashes to escape dollar signs and backticks; or you can put the static text in a variable.

Name='Rich Ba$tard'
dough='$$$dollars$$$'
cat <<____HERE
$Name, you can win a lot of $dough this week!
Notice that \`backticks' need escaping if you want
literal text, not `pwd`, just like in variables like
\$HOME (current value: $HOME)
____HERE

Demo: https://ideone.com/rMF2XA

Note that any of the quoting mechanisms -- \____HERE or "____HERE" or '____HERE' -- will disable all variable interpolation, and turn the here-document into a piece of literal text.

A common task is to combine local variables with script which should be evaluated by a different shell, programming language, or remote host.

local=$(uname)
ssh -t remote <<:
    echo "$local is the value from the host which ran the ssh command"
    # Prevent here doc from expanding locally; remote won't see backslash
    remote=\$(uname)
    # Same here
    echo "\$remote is the value from the host we ssh:ed to"
:

OS X cp command in Terminal - No such file or directory

I know this question has already been answered, but another option is simply to open the destination and source folders in Finder and then drag and drop them into the terminal. The paths will automatically be copied and properly formatted (thus negating the need to actually figure out proper file names/extensions).

I have to do over-network copies between Mac and Windows machines, sometimes fairly deep down in filetrees, and have found this the most effective way to do so.

So, as an example:

cp -r [drag and drop source folder from finder] [drag and drop destination folder from finder]

Get HTML inside iframe using jQuery

Just for reference's sake. This is how to do it with JQuery (useful for instance when you cannot query by element id):

$('#iframe').get(0).contentWindow.document.body.innerHTML

reCAPTCHA ERROR: Invalid domain for site key

I was using localhost during unit testing when my recaptcha key was registered to 127.0.0.1. So I changed my browser to point to 127.0.0.1 and it started working. Although I was able to add "localhost" to the list of domains in my ReCaptcha Key Settings, I am still unable to unit test using localhost. I have to use the loopback IP address 127.0.0.1.

What is the difference between Set and List?

List

  1. Is an Ordered grouping of elements.
  2. List is used to collection of elements with duplicates.
  3. New methods are defined inside List interface.

Set

  1. Is an Unordered grouping of elements.
  2. Set is used to collection of elements without duplicates.
  3. No new methods are defined inside Set interface, so we have to use Collection interface methods only with Set subclasses.

Getting distance between two points based on latitude/longitude

import numpy as np


def Haversine(lat1,lon1,lat2,lon2, **kwarg):
    """
    This uses the ‘haversine’ formula to calculate the great-circle distance between two points – that is, 
    the shortest distance over the earth’s surface – giving an ‘as-the-crow-flies’ distance between the points 
    (ignoring any hills they fly over, of course!).
    Haversine
    formula:    a = sin²(?f/2) + cos f1 · cos f2 · sin²(??/2)
    c = 2 · atan2( va, v(1-a) )
    d = R · c
    where   f is latitude, ? is longitude, R is earth’s radius (mean radius = 6,371km);
    note that angles need to be in radians to pass to trig functions!
    """
    R = 6371.0088
    lat1,lon1,lat2,lon2 = map(np.radians, [lat1,lon1,lat2,lon2])

    dlat = lat2 - lat1
    dlon = lon2 - lon1
    a = np.sin(dlat/2)**2 + np.cos(lat1) * np.cos(lat2) * np.sin(dlon/2) **2
    c = 2 * np.arctan2(a**0.5, (1-a)**0.5)
    d = R * c
    return round(d,4)

Why is IoC / DI not common in Python?

I agree with @Jorg in the point that DI/IoC is possible, easier and even more beautiful in Python. What's missing is the frameworks supporting it, but there are a few exceptions. To point a couple of examples that come to my mind:

  • Django comments let you wire your own Comment class with your custom logic and forms. [More Info]

  • Django let you use a custom Profile object to attach to your User model. This is not completely IoC but is a good approach. Personally I'd like to replace the hole User model as the comments framework does. [More Info]

Python: importing a sub-package or sub-module

You seem to be misunderstanding how import searches for modules. When you use an import statement it always searches the actual module path (and/or sys.modules); it doesn't make use of module objects in the local namespace that exist because of previous imports. When you do:

import package.subpackage.module
from package.subpackage import module
from module import attribute1

The second line looks for a package called package.subpackage and imports module from that package. This line has no effect on the third line. The third line just looks for a module called module and doesn't find one. It doesn't "re-use" the object called module that you got from the line above.

In other words from someModule import ... doesn't mean "from the module called someModule that I imported earlier..." it means "from the module named someModule that you find on sys.path...". There is no way to "incrementally" build up a module's path by importing the packages that lead to it. You always have to refer to the entire module name when importing.

It's not clear what you're trying to achieve. If you only want to import the particular object attribute1, just do from package.subpackage.module import attribute1 and be done with it. You need never worry about the long package.subpackage.module once you've imported the name you want from it.

If you do want to have access to the module to access other names later, then you can do from package.subpackage import module and, as you've seen you can then do module.attribute1 and so on as much as you like.

If you want both --- that is, if you want attribute1 directly accessible and you want module accessible, just do both of the above:

from package.subpackage import module
from package.subpackage.module import attribute1
attribute1 # works
module.someOtherAttribute # also works

If you don't like typing package.subpackage even twice, you can just manually create a local reference to attribute1:

from package.subpackage import module
attribute1 = module.attribute1
attribute1 # works
module.someOtherAttribute #also works

MySQL, update multiple tables with one query

That's usually what stored procedures are for: to implement several SQL statements in a sequence. Using rollbacks, you can ensure that they are treated as one unit of work, ie either they are all executed or none of them are, to keep data consistent.

Is there a way to 'pretty' print MongoDB shell output to a file?

you can use this command to acheive it:

mongo admin -u <userName> -p <password> --quiet --eval "cursor = rs.status(); printjson(cursor)" > output.json

What does EntityManager.flush do and why do I need to use it?

So when you call EntityManager.persist(), it only makes the entity get managed by the EntityManager and adds it (entity instance) to the Persistence Context. An Explicit flush() will make the entity now residing in the Persistence Context to be moved to the database (using a SQL).

Without flush(), this (moving of entity from Persistence Context to the database) will happen when the Transaction to which this Persistence Context is associated is committed.

How to convert a HTMLElement to a string

You can get the 'outer-html' by cloning the element, adding it to an empty,'offstage' container, and reading the container's innerHTML.

This example takes an optional second parameter.

Call document.getHTML(element, true) to include the element's descendents.

document.getHTML= function(who, deep){
    if(!who || !who.tagName) return '';
    var txt, ax, el= document.createElement("div");
    el.appendChild(who.cloneNode(false));
    txt= el.innerHTML;
    if(deep){
        ax= txt.indexOf('>')+1;
        txt= txt.substring(0, ax)+who.innerHTML+ txt.substring(ax);
    }
    el= null;
    return txt;
}

Updating a java map entry

You just use the method

public Object put(Object key, Object value)

if the key was already present in the Map then the previous value is returned.

How to format LocalDate to string?

System.out.println(LocalDate.now().format(DateTimeFormatter.ofPattern("dd.MMMM yyyy")));

The above answer shows it for today

How do I deal with corrupted Git object files?

In general, fixing corrupt objects can be pretty difficult. However, in this case, we're confident that the problem is an aborted transfer, meaning that the object is in a remote repository, so we should be able to safely remove our copy and let git get it from the remote, correctly this time.

The temporary object file, with zero size, can obviously just be removed. It's not going to do us any good. The corrupt object which refers to it, d4a0e75..., is our real problem. It can be found in .git/objects/d4/a0e75.... As I said above, it's going to be safe to remove, but just in case, back it up first.

At this point, a fresh git pull should succeed.

...assuming it was going to succeed in the first place. In this case, it appears that some local modifications prevented the attempted merge, so a stash, pull, stash pop was in order. This could happen with any merge, though, and didn't have anything to do with the corrupted object. (Unless there was some index cleanup necessary, and the stash did that in the process... but I don't believe so.)

How to add parameters into a WebRequest?

If these are the parameters of url-string then you need to add them through '?' and '&' chars, for example http://example.com/index.aspx?username=Api_user&password=Api_password.

If these are the parameters of POST request, then you need to create POST data and write it to request stream. Here is sample method:

private static string doRequestWithBytesPostData(string requestUri, string method, byte[] postData,
                                        CookieContainer cookieContainer,
                                        string userAgent, string acceptHeaderString,
                                        string referer,
                                        string contentType, out string responseUri)
        {
            var result = "";
            if (!string.IsNullOrEmpty(requestUri))
            {
                var request = WebRequest.Create(requestUri) as HttpWebRequest;
                if (request != null)
                {
                    request.KeepAlive = true;
                    var cachePolicy = new RequestCachePolicy(RequestCacheLevel.BypassCache);
                    request.CachePolicy = cachePolicy;
                    request.Expect = null;
                    if (!string.IsNullOrEmpty(method))
                        request.Method = method;
                    if (!string.IsNullOrEmpty(acceptHeaderString))
                        request.Accept = acceptHeaderString;
                    if (!string.IsNullOrEmpty(referer))
                        request.Referer = referer;
                    if (!string.IsNullOrEmpty(contentType))
                        request.ContentType = contentType;
                    if (!string.IsNullOrEmpty(userAgent))
                        request.UserAgent = userAgent;
                    if (cookieContainer != null)
                        request.CookieContainer = cookieContainer;

                    request.Timeout = Constants.RequestTimeOut;

                    if (request.Method == "POST")
                    {
                        if (postData != null)
                        {
                            request.ContentLength = postData.Length;
                            using (var dataStream = request.GetRequestStream())
                            {
                                dataStream.Write(postData, 0, postData.Length);
                            }
                        }
                    }

                    using (var httpWebResponse = request.GetResponse() as HttpWebResponse)
                    {
                        if (httpWebResponse != null)
                        {
                            responseUri = httpWebResponse.ResponseUri.AbsoluteUri;
                            cookieContainer.Add(httpWebResponse.Cookies);
                            using (var streamReader = new StreamReader(httpWebResponse.GetResponseStream()))
                            {
                                result = streamReader.ReadToEnd();
                            }
                            return result;
                        }
                    }
                }
            }
            responseUri = null;
            return null;
        }

How to set div's height in css and html

<div style="height: 100px;"> </div>

OR

<div id="foo"/> and set the style as #foo { height: 100px; }
<div class="bar"/> and set the style as .bar{ height: 100px;  }

Can I use CASE statement in a JOIN condition?

I think you need two case statements:

SELECT  *
FROM    sys.indexes i
    JOIN sys.partitions p
        ON i.index_id = p.index_id 
    JOIN sys.allocation_units a
        ON 
        -- left side of join on statement
            CASE
               WHEN a.type IN (1, 3)
                   THEN a.container_id
               WHEN a.type IN (2)
                   THEN a.container_id
            END 
        = 
        -- right side of join on statement
            CASE
               WHEN a.type IN (1, 3)
                   THEN p.hobt_id
               WHEN a.type IN (2)
                   THEN p.partition_id
            END             

This is because:

  • the CASE statement returns a single value at the END
  • the ON statement compares two values
  • your CASE statement was doing the comparison inside of the CASE statement. I would guess that if you put your CASE statement in your SELECT you would get a boolean '1' or '0' indicating whether the CASE statement evaluated to True or False

What is the difference between CHARACTER VARYING and VARCHAR in PostgreSQL?

The only difference is that CHARACTER VARYING is more human friendly than VARCHAR

Flutter Countdown Timer

You can use this plugin timer_builder

timer_builder widget that rebuilds itself on scheduled, periodic, or dynamically generated time events.

Examples

Periodic rebuild

import 'package:timer_builder/timer_builder.dart';

class ClockWidget extends StatelessWidget {

  @override
  Widget build(BuildContext context) {
    return TimerBuilder.periodic(Duration(seconds: 1),
      builder: (context) {
        return Text("${DateTime.now()}");
      }
    );
  }
  
}

Rebuild on a schedule

import 'package:timer_builder/timer_builder.dart';

class StatusIndicator extends StatelessWidget {

  final DateTime startTime;
  final DateTime endTime;
  
  StatusIndicator(this.startTime, this.endTime);
  
  @override
  Widget build(BuildContext context) {
    return TimerBuilder.scheduled([startTime, endTime],
      builder: (context) {
        final now = DateTime.now();
        final started = now.compareTo(startTime) >= 0;
        final ended = now.compareTo(endTime) >= 0;
        return Text(started ? ended ? "Ended": "Started": "Not Started");
      }
    );
  }
  
}

enter image description here

How can I rotate an HTML <div> 90 degrees?

Use transform: rotate(90deg):

_x000D_
_x000D_
#container_2 {_x000D_
    border: 1px solid;_x000D_
    padding: .5em;_x000D_
    width: 5em;_x000D_
    height: 5em;_x000D_
    transition: .3s all;  /* rotate gradually instead of instantly */_x000D_
}_x000D_
_x000D_
#container_2:hover {_x000D_
    -webkit-transform: rotate(90deg);  /* to support Safari and Android browser */_x000D_
    -ms-transform: rotate(90deg);      /* to support IE 9 */_x000D_
    transform: rotate(90deg);_x000D_
}
_x000D_
<div id="container_2">This box should be rotated 90&deg; on hover.</div>
_x000D_
_x000D_
_x000D_

Click "Run code snippet", then hover over the box to see the effect of the transform.

Realistically, no other prefixed entries are needed. See Can I use CSS3 Transforms?

ListView with OnItemClickListener

If you define your ListView programatically:

mListView.setDescendantFocusability(ListView.FOCUS_BLOCK_DESCENDANTS);

Unsupported major.minor version 52.0

Upgrade your Andorra version to JDK 1.8.

This is a version mismatch that your compiler is looking for Java version 8 and you have Java version 7.

You can run an app build in version 7 in version 8, but you can't do vice versa because when it comes to higher levels, versions are embedded with more features, enhancements rather than previous versions.

Download JDK version from this link

And set your JDK path for this

What is the Difference Between read() and recv() , and Between send() and write()?

Per the first hit on Google

read() is equivalent to recv() with a flags parameter of 0. Other values for the flags parameter change the behaviour of recv(). Similarly, write() is equivalent to send() with flags == 0.

How to convert from Hex to ASCII in JavaScript?

An optimized version of the implementation of the reverse function proposed by @michieljoris (according to the comments of @Beterraba and @Mala):

_x000D_
_x000D_
function a2hex(str) {_x000D_
  var hex = '';_x000D_
  for (var i = 0, l = str.length; i < l; i++) {_x000D_
    var hexx = Number(str.charCodeAt(i)).toString(16);_x000D_
    hex += (hexx.length > 1 && hexx || '0' + hexx);_x000D_
  }_x000D_
  return hex;_x000D_
}_x000D_
alert(a2hex('2460')); // display 32343630
_x000D_
_x000D_
_x000D_

How do you make Vim unhighlight what you searched for?

            *:noh* *:nohlsearch*
:noh[lsearch]       Stop the highlighting for the 'hlsearch' option.  It
            is automatically turned back on when using a search
            command, or setting the 'hlsearch' option.
            This command doesn't work in an autocommand, because
            the highlighting state is saved and restored when
            executing autocommands |autocmd-searchpat|.
            Same thing for when invoking a user function.

I found it just under :help #, which I keep hitting all the time, and which highlights all the words on the current page like the current one.

Automatic creation date for Django model form objects?

Well, the above answer is correct, auto_now_add and auto_now would do it, but it would be better to make an abstract class and use it in any model where you require created_at and updated_at fields.

class TimeStampMixin(models.Model):
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        abstract = True

Now anywhere you want to use it you can do a simple inherit and you can use timestamp in any model you make like.

class Posts(TimeStampMixin):
    name = models.CharField(max_length=50)
    ...
    ...

In this way, you can leverage object-oriented reusability, in Django DRY(don't repeat yourself)

Declare and Initialize String Array in VBA

Using

Dim myarray As Variant

works but

Dim myarray As String

doesn't so I sitck to Variant

How to get domain URL and application name?

I would strongly suggest you to read through the docs, for similar methods. If you are interested in context path, have a look here, ServletContext.getContextPath().

How to define several include path in Makefile

Make's substitutions feature is nice and helped me to write

%.i: src/%.c $(INCLUDE)
        gcc -E $(CPPFLAGS) $(INCLUDE:%=-I %) $< > $@

You might find this useful, because it asks make to check for changes in include folders too

How to Consolidate Data from Multiple Excel Columns All into One Column

Best and Simple solution to follow:

Select the range of the columns you want to be copied to single column

Copy the range of cells (multiple columns)

Open Notepad++

Paste the selected range of cells

Press Ctrl+H, replace \t by \n and click on replace all

all the multiple columns fall under one single column

now copy the same and paste in excel

Simple and effective solution for those who dont want to waste time coding in VBA

How to return a result from a VBA function

Just setting the return value to the function name is still not exactly the same as the Java (or other) return statement, because in java, return exits the function, like this:

public int test(int x) {
    if (x == 1) {
        return 1; // exits immediately
    }

    // still here? return 0 as default.
    return 0;
}

In VB, the exact equivalent takes two lines if you are not setting the return value at the end of your function. So, in VB the exact corollary would look like this:

Public Function test(ByVal x As Integer) As Integer
    If x = 1 Then
        test = 1 ' does not exit immediately. You must manually terminate...
        Exit Function ' to exit
    End If

    ' Still here? return 0 as default.
    test = 0
    ' no need for an Exit Function because we're about to exit anyway.
End Function 

Since this is the case, it's also nice to know that you can use the return variable like any other variable in the method. Like this:

Public Function test(ByVal x As Integer) As Integer

    test = x ' <-- set the return value

    If test <> 1 Then ' Test the currently set return value
        test = 0 ' Reset the return value to a *new* value
    End If

End Function 

Or, the extreme example of how the return variable works (but not necessarily a good example of how you should actually code)—the one that will keep you up at night:

Public Function test(ByVal x As Integer) As Integer

    test = x ' <-- set the return value

    If test > 0 Then

        ' RECURSIVE CALL...WITH THE RETURN VALUE AS AN ARGUMENT,
        ' AND THE RESULT RESETTING THE RETURN VALUE.
        test = test(test - 1)

    End If

End Function

How do I drop table variables in SQL-Server? Should I even do this?

Indeed, you don't need to drop a @local_variable.

But if you use #local_table, it can be done, e.g. it's convenient to be able to re-execute a query several times.

SELECT *
INTO #recent_records
FROM dbo.my_table t
WHERE t.CreatedOn > '2021-01-01'
;

SELECT *
FROM #recent_records
;

/*
  can DROP here, otherwise will fail with the following error
  on re-execution in the same window (I use SSMS DB client):

  Msg 2714, Level ..., State ..., Line ...
  There is already an object named '#recent_records' in the database.
*/
DROP TABLE #recent_records
;

You can also put your SELECT statement in a TRANSACTION to be able to re-execute without an explicit DROP:

BEGIN TRANSACTION

  SELECT *
  INTO #recent_records
  FROM dbo.my_table t
  WHERE t.CreatedOn > '2021-01-01'
  ;

  SELECT *
  FROM #recent_records
  ;

ROLLBACK

How to execute two mysql queries as one in PHP/MYSQL?

You'll have to use the MySQLi extension if you don't want to execute a query twice:

if (mysqli_multi_query($link, $query))
{
    $result1 = mysqli_store_result($link);
    $result2 = null;

    if (mysqli_more_results($link))
    {
        mysqli_next_result($link);
        $result2 = mysqli_store_result($link);
    }

    // do something with both result sets.

    if ($result1)
        mysqli_free_result($result1);

    if ($result2)
        mysqli_free_result($result2);
}

matplotlib savefig() plots different from show()

I have fixed this in my matplotlib source, but it's not a pretty fix. However, if you, like me, are very particular about how the graph looks, it's worth it.

The issue seems to be in the rendering backends; they each get the correct values for linewidth, font size, etc., but that comes out slightly larger when rendered as a PDF or PNG than when rendered with show().

I added a few lines to the source for PNG generation, in the file matplotlib/backends/backend_agg.py. You could make similar changes for each backend you use, or find a way to make a more clever change in a single location ;)

Added to my matplotlib/backends/backend_agg.py file:

    # The top of the file, added lines 42 - 44
42  # @warning: CHANGED FROM SOURCE to draw thinner lines
43  PATH_SCALAR = .8
44  FONT_SCALAR = .95

    # In the draw_markers method, added lines 90 - 91
89  def draw_markers(self, *kl, **kw):
90      # @warning: CHANGED FROM SOURCE to draw thinner lines
91      kl[0].set_linewidth(kl[0].get_linewidth()*PATH_SCALAR)
92      return self._renderer.draw_markers(*kl, **kw)

    # At the bottom of the draw_path method, added lines 131 - 132:
130 else:
131     # @warning: CHANGED FROM SOURCE to draw thinner lines
132     gc.set_linewidth(gc.get_linewidth()*PATH_SCALAR)
133     self._renderer.draw_path(gc, path, transform, rgbFace)

    # At the bottom of the _get_agg_font method, added line 242 and the *FONT_SCALAR
241     font.clear()
242     # @warning: CHANGED FROM SOURCE to draw thinner lines
243     size = prop.get_size_in_points()*FONT_SCALAR
244     font.set_size(size, self.dpi)

So that suits my needs for now, but, depending on what you're doing, you may want to implement similar changes in other methods. Or find a better way to do the same without so many line changes!

Update: After posting an issue to the matplotlib project at Github, I was able to track down the source of my problem: I had changed the figure.dpi setting in the matplotlibrc file. If that value is different than the default, my savefig() images come out different, even if I set the savefig dpi to be the same as the figure dpi. So, instead of changing the source as above, I just kept the figure.dpi setting as the default 80, and was able to generate images with savefig() that looked like images from show().

Leon, had you also changed that setting?

Load and execution sequence of a web page?

If you're asking this because you want to speed up your web site, check out Yahoo's page on Best Practices for Speeding Up Your Web Site. It has a lot of best practices for speeding up your web site.

Python sys.argv lists and indexes

As explained in the different asnwers already, sys.argv contains the command line arguments that called your Python script.

However, Python comes with libraries that help you parse command line arguments very easily. Namely, the new standard argparse. Using argparse would spare you the need to write a lot of boilerplate code.

How to design RESTful search/filtering?

It seems that resource filtering/searching can be implemented in a RESTful way. The idea is to introduce a new endpoint called /filters/ or /api/filters/.

Using this endpoint filter can be considered as a resource and hence created via POST method. This way - of course - body can be used to carry all the parameters as well as complex search/filter structures can be created.

After creating such filter there are two possibilities to get the search/filter result.

  1. A new resource with unique ID will be returned along with 201 Created status code. Then using this ID a GET request can be made to /api/users/ like:

    GET /api/users/?filterId=1234-abcd
    
  2. After new filter is created via POST it won't reply with 201 Created but at once with 303 SeeOther along with Location header pointing to /api/users/?filterId=1234-abcd. This redirect will be automatically handled via underlying library.

In both scenarios two requests need to be made to get the filtered results - this may be considered as a drawback, especially for mobile applications. For mobile applications I'd use single POST call to /api/users/filter/.

How to keep created filters?

They can be stored in DB and used later on. They can also be stored in some temporary storage e.g. redis and have some TTL after which they will expire and will be removed.

What are the advantages of this idea?

Filters, filtered results are cacheable and can be even bookmarked.

Vue.js unknown custom element

Be sure that you have added the component to the components.

For example:

export default {
data() {
    return {}
},
components: {
    'lead-status-modal': LeadStatusModal,
},
}

ERROR 1064 (42000): You have an error in your SQL syntax; Want to configure a password as root being the user

Try this:

UPDATE mysql.user SET password=password("elephant7") where user="root"

How to specify preference of library path?

Specifying the absolute path to the library should work fine:

g++ /my/dir/libfoo.so.0  ...

Did you remember to remove the -lfoo once you added the absolute path?

Remove whitespaces inside a string in javascript

For space-character removal use

"hello world".replace(/\s/g, "");

for all white space use the suggestion by Rocket in the comments below!

"make_sock: could not bind to address [::]:443" when restarting apache (installing trac and mod_wsgi)

I use apache version 2.4.27, also have this problem, solved it through modify

the conf/extra/httpdahssl.conf,comment the 18 line content(Listen 443 https),it works fine.

VS2010 command prompt gives error: Cannot determine the location of the VS Common Tools folder

I had this not too long ago as a result of registry editing being blocked by a group policy.

The specific problem is that reg is denied access to the registry. I solved this by replicating the 'reg.exe' using Microsoft.Win32.Registry in a C# program, and then substituting all calls to reg, with my alternative program. You need to update:

  • VCVarsQuery.bat
  • VsDevCmd.bat
  • VsVars32.bat

In the %VSxxxCOMNTOOLS% folder (usually resolves to something like C:\Program Files (x86)\Microsoft Visual Studio XX.X\Common7\Tools)

    static int Main(string[] args)
    {
        try
        {
            var targetRegistry = args[1].Substring(0, 4);
            var targetKey = args[1].Substring(5);

            string targetValue = null;
            if (args[2].ToLower() == "/v")
            {
                targetValue = args[3];
            }
            else
            {
                return 1;
            }

            var hkey = targetRegistry == "HKLM" ? Registry.LocalMachine : Registry.CurrentUser;
            var key = hkey.OpenSubKey(targetKey);



            var result = key.GetValue(targetValue);
            Console.WriteLine();
            Console.WriteLine(key.Name);
            Console.WriteLine("    {0}    REG_SZ    {2}", targetValue, key.GetValueKind(targetValue), result);
            Console.WriteLine();
            Console.WriteLine();

            return 0;
        }
        catch
        {
            return 1;
        }
    }

In cases like this, you can also use my alternative reg implementation here.

How to get Android application id?

For getting AppId (or package name, how some says), just call this:

But be sure that you importing BuildConfig with your app id packages path

BuildConfig.APPLICATION_ID 

Force IE10 to run in IE10 Compatibility View?

I had the exact same problem, this - "meta http-equiv="X-UA-Compatible" content="IE=7">" works great in IE8 and IE9, but not in IE10. There is a bug in the server browser definition files that shipped with .NET 2.0 and .NET 4, namely that they contain definitions for a certain range of browser versions. But the versions for some browsers (like IE 10) aren't within those ranges any more. Therefore, ASP.NET sees them as unknown browsers and defaults to a down-level definition, which has certain inconveniences, like that it does not support features like JavaScript.

My thanks to Scott Hanselman for this fix.

Here is the link -

http://www.hanselman.com/blog/BugAndFixASPNETFailsToDetectIE10CausingDoPostBackIsUndefinedJavaScriptErrorOrMaintainFF5ScrollbarPosition.aspx

This MS KP fix just adds missing files to the asp.net on your server. I installed it and rebooted my server and it now works perfectly. I would have thought that MS would have given this fix a wider distribution.

Rick

How to debug a Flask app

Running the app in development mode will show an interactive traceback and console in the browser when there is an error. To run in development mode, set the FLASK_ENV=development environment variable then use the flask run command (remember to point FLASK_APP to your app as well).

For Linux, Mac, Linux Subsystem for Windows, Git Bash on Windows, etc.:

export FLASK_APP=myapp
export FLASK_ENV=development
flask run

For Windows CMD, use set instead of export:

set FLASK_ENV=development

For PowerShell, use $env:

$env:FLASK_ENV = "development"

Prior to Flask 1.0, this was controlled by the FLASK_DEBUG=1 environment variable instead.

If you're using the app.run() method instead of the flask run command, pass debug=True to enable debug mode.

Tracebacks are also printed to the terminal running the server, regardless of development mode.

If you're using PyCharm, VS Code, etc., you can take advantage of its debugger to step through the code with breakpoints. The run configuration can point to a script calling app.run(debug=True, use_reloader=False), or point it at the venv/bin/flask script and use it as you would from the command line. You can leave the reloader disabled, but a reload will kill the debugging context and you will have to catch a breakpoint again.

You can also use pdb, pudb, or another terminal debugger by calling set_trace in the view where you want to start debugging.


Be sure not to use too-broad except blocks. Surrounding all your code with a catch-all try... except... will silence the error you want to debug. It's unnecessary in general, since Flask will already handle exceptions by showing the debugger or a 500 error and printing the traceback to the console.

Syntax for async arrow function

Basic Example

folder = async () => {
    let fold = await getFold();
    //await localStorage.save('folder');
    return fold;
  };

Select statement to find duplicates on certain fields

This is a fun solution with SQL Server 2005 that I like. I'm going to assume that by "for every record except for the first one", you mean that there is another "id" column that we can use to identify which row is "first".

SELECT id
    , field1
    , field2
    , field3
FROM
(
    SELECT id
        , field1
        , field2
        , field3
        , RANK() OVER (PARTITION BY field1, field2, field3 ORDER BY id ASC) AS [rank]
    FROM table_name
) a
WHERE [rank] > 1

Getting the docstring from a function

Interactively, you can display it with

help(my_func)

Or from code you can retrieve it with

my_func.__doc__

Npm Please try using this command again as root/administrator

If you're using TFS or any other source control for your project that sets your checked in files to readonly mode, then you gotta make sure package.json is checked out before running npm install. I've made this mistake plenty of times.

How to access remote server with local phpMyAdmin client?

I would have added this as a comment, but my reputation is not yet high enough.

Under version 4.5.4.1deb2ubuntu2, and I am guessing any other versions 4.5.x or newer. There is no need to modify the config.inc.php file at all. Instead go one more directory down conf.d.

Create a new file with the '.php' extension and add the lines. This is a better modularized approach and isolates each remote database server access information.

List to array conversion to use ravel() function

create an int array and a list

from array import array
listA = list(range(0,50))
for item in listA:
    print(item)
arrayA = array("i", listA)
for item in arrayA:
    print(item)

Reset Windows Activation/Remove license key

On Windows XP -

  1. Reboot into "Safe mode with Command Prompt"
  2. Type "explorer" in the command prompt that comes up and push [Enter]
  3. Click on Start>Run, and type the following :

    rundll32.exe syssetup,SetupOobeBnk

Reboot, and login as normal.

This will reset the 30 day timer for activation back to 30 days so you can enter in the key normally.

Upload Progress Bar in PHP

I'm sorry to say that to the best of my knowledge a pure PHP upload progress bar, or even a PHP/Javascript upload progress bar is not possible because of how PHP works. Your best bet is to use some form of Flash uploader.

AFAIK This is because your script is not executed until all the superglobals are populated, which includes $_FILES. By the time your PHP script gets called, the file is fully uploaded.

EDIT: This is no longer true. It was in 2010.

How to create a byte array in C++?

Byte is not a standard type in C/C++, so it is represented by char.

An advantage of this is that you can treat a basic_string as a byte array allowing for safe storage and function passing. This will help you avoid the memory leaks and segmentation faults you might encounter when using the various forms of char[] and char*.

For example, this creates a string as a byte array of null values:

typedef basic_string<unsigned char> u_string;

u_string bytes = u_string(16,'\0');

This allows for standard bitwise operations with other char values, including those stored in other string variables. For example, to XOR the char values of another u_string across bytes:

u_string otherBytes = "some more chars, which are just bytes";
for(int i = 0; i < otherBytes.length(); i++)
    bytes[i%16] ^= (int)otherBytes[i];

Scikit-learn: How to obtain True Positive, True Negative, False Positive and False Negative

You can obtain all of the parameters from the confusion matrix. The structure of the confusion matrix(which is 2X2 matrix) is as follows (assuming the first index is related to the positive label, and the rows are related to the true labels):

TP|FN
FP|TN

So

TP = cm[0][0]
FN = cm[0][1]
FP = cm[1][0]
TN = cm[1][1]

More details at https://en.wikipedia.org/wiki/Confusion_matrix

How do you implement a circular buffer in C?

The simplest solution would be to keep track of the item size and the number of items, and then create a buffer of the appropriate number of bytes:

typedef struct circular_buffer
{
    void *buffer;     // data buffer
    void *buffer_end; // end of data buffer
    size_t capacity;  // maximum number of items in the buffer
    size_t count;     // number of items in the buffer
    size_t sz;        // size of each item in the buffer
    void *head;       // pointer to head
    void *tail;       // pointer to tail
} circular_buffer;

void cb_init(circular_buffer *cb, size_t capacity, size_t sz)
{
    cb->buffer = malloc(capacity * sz);
    if(cb->buffer == NULL)
        // handle error
    cb->buffer_end = (char *)cb->buffer + capacity * sz;
    cb->capacity = capacity;
    cb->count = 0;
    cb->sz = sz;
    cb->head = cb->buffer;
    cb->tail = cb->buffer;
}

void cb_free(circular_buffer *cb)
{
    free(cb->buffer);
    // clear out other fields too, just to be safe
}

void cb_push_back(circular_buffer *cb, const void *item)
{
    if(cb->count == cb->capacity){
        // handle error
    }
    memcpy(cb->head, item, cb->sz);
    cb->head = (char*)cb->head + cb->sz;
    if(cb->head == cb->buffer_end)
        cb->head = cb->buffer;
    cb->count++;
}

void cb_pop_front(circular_buffer *cb, void *item)
{
    if(cb->count == 0){
        // handle error
    }
    memcpy(item, cb->tail, cb->sz);
    cb->tail = (char*)cb->tail + cb->sz;
    if(cb->tail == cb->buffer_end)
        cb->tail = cb->buffer;
    cb->count--;
}

Can't choose class as main class in IntelliJ

Here is the complete procedure for IDEA IntelliJ 2019.3:

  1. File > Project Structure

  2. Under Project Settings > Modules

  3. Under 'Sources' tab, right-click on 'src' folder and select 'Sources'.

  4. Apply changes.

PHP: convert spaces in string into %20?

The plus sign is the historic encoding for a space character in URL parameters, as documented in the help for the urlencode() function.

That same page contains the answer you need - use rawurlencode() instead to get RFC 3986 compatible encoding.

What is a unix command for deleting the first N characters of a line?

I think awk would be the best tool for this as it can both filter and perform the necessary string manipulation functions on filtered lines:

tail -f logfile | awk '/org.springframework/ {print substr($0, 6)}'

or

tail -f logfile | awk '/org.springframework/ && sub(/^.{5}/,"",$0)'

Removing an element from an Array (Java)

The best choice would be to use a collection, but if that is out for some reason, use arraycopy. You can use it to copy from and to the same array at a slightly different offset.

For example:

public void removeElement(Object[] arr, int removedIdx) {
    System.arraycopy(arr, removedIdx + 1, arr, removedIdx, arr.length - 1 - removedIdx);
}

Edit in response to comment:

It's not another good way, it's really the only acceptable way--any tools that allow this functionality (like Java.ArrayList or the apache utils) will use this method under the covers. Also, you REALLY should be using ArrayList (or linked list if you delete from the middle a lot) so this shouldn't even be an issue unless you are doing it as homework.

To allocate a collection (creates a new array), then delete an element (which the collection will do using arraycopy) then call toArray on it (creates a SECOND new array) for every delete brings us to the point where it's not an optimizing issue, it's criminally bad programming.

Suppose you had an array taking up, say, 100mb of ram. Now you want to iterate over it and delete 20 elements.

Give it a try...

I know you ASSUME that it's not going to be that big, or that if you were deleting that many at once you'd code it differently, but I've fixed an awful lot of code where someone made assumptions like that.

Setting background images in JFrame

Try this :

import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;


public class Test {

    public static void main(String[] args) {
        JFrame f = new JFrame();
        try {
            f.setContentPane(new JLabel(new ImageIcon(ImageIO.read(new File("test.jpg")))));
        } catch (IOException e) {
            e.printStackTrace();
        }
        f.pack();
        f.setVisible(true);
    }

}

By the way, this will result in the content pane not being a container. If you want to add things to it you have to subclass a JPanel and override the paintComponent method.

Variables not showing while debugging in Eclipse

In my case,I think the potential cause is Variables View did't initial properly. Variables View init blank Alternative is enter another breakpoint before right code need to change variables.After entering the second breakpoint(above menthioned) added,eclipse will refresh the view and all things should be normal again.

HTML5 LocalStorage: Checking if a key exists

Quoting from the specification:

The getItem(key) method must return the current value associated with the given key. If the given key does not exist in the list associated with the object then this method must return null.

You should actually check against null.

if (localStorage.getItem("username") === null) {
  //...
}

How to open local files in Swagger-UI

I could not get Adam Taras's answer to work (i.e. using the relative path ../my.json).

Here was my solution (pretty quick and painless if you have node installed):

  • With Node, globally install package http-server npm install -g http-server
  • Change directories to where my.json is located, and run the command http-server --cors (CORS has to be enabled for this to work)
  • Open swagger ui (i.e. dist/index.html)
  • Type http://localhost:8080/my.json in input field and click "Explore"

How to select last one week data from today's date

Yes, the syntax is accurate and it should be fine.

Here is the SQL Fiddle Demo I created for your particular case

create table sample2
(
    id int primary key,
    created_date date,
    data varchar(10)
  )

insert into sample2 values (1,'2012-01-01','testing');

And here is how to select the data

SELECT Created_Date
FROM sample2
WHERE Created_Date >= DATEADD(day,-11117, GETDATE())

Working with select using AngularJS's ng-options

I'm learning AngularJS and was struggling with selection as well. I know this question is already answered, but I wanted to share some more code nevertheless.

In my test I have two listboxes: car makes and car models. The models list is disabled until some make is selected. If selection in makes listbox is later reset (set to 'Select Make') then the models listbox becomes disabled again AND its selection is reset as well (to 'Select Model'). Makes are retrieved as a resource while models are just hard-coded.

Makes JSON:

[
{"code": "0", "name": "Select Make"},
{"code": "1", "name": "Acura"},
{"code": "2", "name": "Audi"}
]

services.js:

angular.module('makeServices', ['ngResource']).
factory('Make', function($resource){
    return $resource('makes.json', {}, {
        query: {method:'GET', isArray:true}
    });
});

HTML file:

<div ng:controller="MakeModelCtrl">
  <div>Make</div>
  <select id="makeListBox"
      ng-model="make.selected"
      ng-options="make.code as make.name for make in makes"
      ng-change="makeChanged(make.selected)">
  </select>

  <div>Model</div>
  <select id="modelListBox"
     ng-disabled="makeNotSelected"
     ng-model="model.selected"
     ng-options="model.code as model.name for model in models">
  </select>
</div>

controllers.js:

function MakeModelCtrl($scope)
{
    $scope.makeNotSelected = true;
    $scope.make = {selected: "0"};
    $scope.makes = Make.query({}, function (makes) {
         $scope.make = {selected: makes[0].code};
    });

    $scope.makeChanged = function(selectedMakeCode) {
        $scope.makeNotSelected = !selectedMakeCode;
        if ($scope.makeNotSelected)
        {
            $scope.model = {selected: "0"};
        }
    };

    $scope.models = [
      {code:"0", name:"Select Model"},
      {code:"1", name:"Model1"},
      {code:"2", name:"Model2"}
    ];
    $scope.model = {selected: "0"};
}

Android Preventing Double Click On A Button

    button.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View view) {
            //to prevent double click
            button.setOnClickListener(null);
        }
    });

Cocoa Touch: How To Change UIView's Border Color And Thickness?

You can also create border with the color of your wish..

view.layer.borderColor = [UIColor colorWithRed:r/255.0 green:g/255.0 blue:b/255.0 alpha:1.0].CGColor;

*r,g,b are the values between 0 to 255.

ActiveXObject creation error " Automation server can't create object"

Well you can not run code from notepad so that means you are opening up the page from the file system. aka c:/foo/bar/hello.html

When you run the code from the asp.net page, you are running it from localhost. aka http://loalhost:1234/assdf.html

Each of these run in different security zones on IE.

How to write text on a image in windows using python opencv2

I had a similar problem. I would suggest using the PIL library in python as it draws the text in any given font, compared to limited fonts in OpenCV. With PIL you can choose any font installed on your system.

from PIL import ImageFont, ImageDraw, Image
import numpy as np
import cv2

image = cv2.imread("lena.png")

# Convert to PIL Image
cv2_im_rgb = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)
pil_im = Image.fromarray(cv2_im_rgb)

draw = ImageDraw.Draw(pil_im)

# Choose a font
font = ImageFont.truetype("Roboto-Regular.ttf", 50)

# Draw the text
draw.text((0, 0), "Your Text Here", font=font)

# Save the image
cv2_im_processed = cv2.cvtColor(np.array(pil_im), cv2.COLOR_RGB2BGR)
cv2.imwrite("result.png", cv2_im_processed)

result.png

what is the difference between $_SERVER['REQUEST_URI'] and $_GET['q']?

In the context of Drupal, the difference will depend whether clean URLs are on or not.

With them off, $_SERVER['REQUEST_URI'] will have the full path of the page as called w/ /index.php, while $_GET["q"] will just have what is assigned to q.

With them on, they will be nearly identical w/o other arguments, but $_GET["q"] will be missing the leading /. Take a look towards the end of the default .htaccess to see what is going on. They will also differ if additional arguments are passed into the page, eg when a pager is active.

<embed> vs. <object>

Answer updated for 2020:

Both <object> and <embed> are included in the WHAT-WG HTML Living Standard (Sept 2020).


<object>

The object element can represent an external resource, which, depending on the type of the resource, will either be treated as an image, as a child browsing context, or as an external resource to be processed by a plugin.


<embed>

The embed element provides an integration point for an external (typically non-HTML) application or interactive content.


Are there advantages/disadvantages to using one tag vs. the other?

The opinion of Mozilla Developer Network (MDN) appears (albeit fairly subtly) to very marginally favour <object> over <embed> but overwhelmingly, MDN, wants to recommend that wherever you can, you avoid embedding external content entirely.

[...] you are unlikely to use these elements very much — Applets haven't been used for years, Flash is no longer very popular, due to a number of reasons (see The case against plugins, below), PDFs tend to be better linked to than embedded, and other content such as images and video have much better, easier elements to handle those. Plugins and these embedding methods are really a legacy technology, and we are mainly mentioning them in case you come across them in certain circumstances like intranets, or enterprise projects.

Once upon a time, plugins were indispensable on the Web. Remember the days when you had to install Adobe Flash Player just to watch a movie online? And then you constantly got annoying alerts about updating Flash Player and your Java Runtime Environment. Web technologies have since grown much more robust, and those days are over. For virtually all applications, it's time to stop delivering content that depends on plugins and start taking advantage of Web technologies instead.

Source: https://developer.mozilla.org/en-US/docs/Learn/HTML/Multimedia_and_embedding/Other_embedding_technologies#The_%3Cembed%3E_and_%3Cobject%3E_elements

What does `set -x` do?

set -x enables a mode of the shell where all executed commands are printed to the terminal. In your case it's clearly used for debugging, which is a typical use case for set -x: printing every command as it is executed may help you to visualize the control flow of the script if it is not functioning as expected.

set +x disables it.

Using JAXB to unmarshal/marshal a List<String>

I used @LiorH's example and expanded it to:


@XmlRootElement(name="List")
public class JaxbList<T>{
    protected List<T> list;

    public JaxbList(){}

    public JaxbList(List<T> list){
        this.list=list;
    }

    @XmlElement(name="Item")
    public List<T> getList(){
        return list;
    }
}

Note, that it uses generics so you can use it with other classes than String. Now, the application code is simply:


    @GET
    @Path("/test2")
    public JaxbList test2(){
        List list=new Vector();
        list.add("a");
        list.add("b");
        return new JaxbList(list);
    }

Why doesn't this simple class exist in the JAXB package? Anyone see anything like it elsewhere?

Preprocessor check if multiple defines are not defined

FWIW, @SergeyL's answer is great, but here is a slight variant for testing. Note the change in logical or to logical and.

main.c has a main wrapper like this:

#if !defined(TEST_SPI) && !defined(TEST_SERIAL) && !defined(TEST_USB)
int main(int argc, char *argv[]) {
  // the true main() routine.
}

spi.c, serial.c and usb.c have main wrappers for their respective test code like this:

#ifdef TEST_USB
int main(int argc, char *argv[]) {
  // the  main() routine for testing the usb code.
}

config.h Which is included by all the c files has an entry like this:

// Uncomment below to test the serial
//#define TEST_SERIAL


// Uncomment below to test the spi code
//#define TEST_SPI

// Uncomment below to test the usb code
#define TEST_USB

Trying to Validate URL Using JavaScript

In a similar situation I got away with this:

someUtils.validateURL = function(url) {
    var parser = document.createElement('a');
    try {
        parser.href = url;
        return !!parser.hostname;
    } catch (e) {
        return false;
    }
};

i.e. why invent the wheel if browsers can do it for you? But, of course, this will only work in the browser.

there are various parts of parsed URL exactly how browser would interpret it:

parser.protocol; // => "http:"
parser.hostname; // => "example.com"
parser.port;     // => "8080"
parser.pathname; // => "/path/"
parser.search;   // => "?search=test"
parser.hash;     // => "#hash"
parser.host;     // => "example.com:3000"

Using these you can improve your validating function depending on the requirements. The only drawback is that it will accept relative URLs and use current page server's host and port. But you can use it for your advantage, by re-assembling the URL from parts and always passing it in full to your AJAX service.

What validateURL won't accept is invalid URL, e.g. http:\:8883 will return false, but :1234 is valid and is interpreted as http://pagehost.example.com/:1234 i.e. as a relative path.

UPDATE

This approach is no longer working with Chrome and other WebKit browsers. Even when URL is invalid, hostname is filled with some value, e.g. taken from base. It still helps to parse parts of URL, but will not allow to validate one.

Possible better no-own-parser approach is to use var parsedURL = new URL(url) and catch exceptions. See e.g. URL API. Supported by all major browsers and NodeJS, although still marked experimental.

Export and Import all MySQL databases at one time

Based on these answers I've made script which backups all databases into separate files, but then compress them into one archive with date as name.

This will not ask for password, can be used in cron. To store password in .my.cnf check this answer https://serverfault.com/a/143587/62749

Made also with comments for those who are not very familiar with bash scripts.

#!/bin/bash

# This script will backup all mysql databases into 
# compressed file named after date, ie: /var/backup/mysql/2016-07-13.tar.bz2

# Setup variables used later

# Create date suffix with "F"ull date format
suffix=$(date +%F)
# Retrieve all database names except information schemas. Use sudo here to skip root password.
dbs=$(sudo mysql --defaults-extra-file=/root/.my.cnf --batch --skip-column-names -e "SHOW DATABASES;" | grep -E -v "(information|performance)_schema")
# Create temporary directory with "-d" option
tmp=$(mktemp -d)
# Set output dir here. /var/backups/ is used by system, 
# so intentionally used /var/backup/ for user backups.
outDir="/var/backup/mysql"
# Create output file name
out="$outDir/$suffix.tar.bz2"

# Actual script

# Check if output directory exists
if [ ! -d "$outDir" ];then
  # Create directory with parent ("-p" option) directories
  sudo mkdir -p "$outDir"
fi

# Loop through all databases
for db in $dbs; do
  # Dump database to temporary directory with file name same as database name + sql suffix
  sudo mysqldump --defaults-extra-file=/root/.my.cnf --databases "$db" > "$tmp/$db.sql"
done

# Go to tmp dir
cd $tmp

# Compress all dumps with bz2, discard any output to /dev/null
sudo tar -jcf "$out" * > "/dev/null"

# Cleanup
cd "/tmp/"
sudo rm -rf "$tmp"

Redeploy alternatives to JRebel

Hotswap Agent is an extension to DCEVM which supports many Java frameworks (reload Spring bean definition, Hibernate entity mapping, logger level setup, ...).

There is also lot of documentation how to setup DCEVM and compiled binaries for Java 1.7.

How to load CSS Asynchronously

The trick to triggering an asynchronous stylesheet download is to use a <link> element and set an invalid value for the media attribute (I'm using media="none", but any value will do). When a media query evaluates to false, the browser will still download the stylesheet, but it won't wait for the content to be available before rendering the page.

<link rel="stylesheet" href="css.css" media="none">

Once the stylesheet has finished downloading the media attribute must be set to a valid value so the style rules will be applied to the document. The onload event is used to switch the media property to all:

<link rel="stylesheet" href="css.css" media="none" onload="if(media!='all')media='all'">

This method of loading CSS will deliver useable content to visitors much quicker than the standard approach. Critical CSS can still be served with the usual blocking approach (or you can inline it for ultimate performance) and non-critical styles can be progressively downloaded and applied later in the parsing / rendering process.

This technique uses JavaScript, but you can cater for non-JavaScript browsers by wrapping the equivalent blocking <link> elements in a <noscript> element:

<link rel="stylesheet" href="css.css" media="none" onload="if(media!='all')media='all'"><noscript><link rel="stylesheet" href="css.css"></noscript>

You can see the operation in www.itcha.edu.sv

enter image description here

Source in http://keithclark.co.uk/

How to use Python requests to fake a browser visit a.k.a and generate User Agent?

The root of the answer is that the person asking the question needs to have a JavaScript interpreter to get what they are after. What I have found is I am able to get all of the information I wanted on a website in json before it was interpreted by JavaScript. This has saved me a ton of time in what would be parsing html hoping each webpage is in the same format.

So when you get a response from a website using requests really look at the html/text because you might find the javascripts JSON in the footer ready to be parsed.

How to clear cache in Yarn?

Run yarn cache clean.


Run yarn help cache in your bash, and you will see:

Usage: yarn cache [ls|clean] [flags]

Options: -h, --help output usage information -V, --version output the version number --offline
--prefer-offline
--strict-semver
--json
--global-folder [path]
--modules-folder [path] rather than installing modules into the node_modules folder relative to the cwd, output them here
--packages-root [path] rather than storing modules into a global packages root, store them here
--mutex [type][:specifier] use a mutex to ensure only one yarn instance is executing

Visit http://yarnpkg.com/en/docs/cli/cache for documentation about this command.

Is it possible to use if...else... statement in React render function?

You should Remember about TERNARY operator

:

so your code will be like this,

render(){
    return (
        <div>
            <Element1/>
            <Element2/>
            // note: code does not work here
            { 
               this.props.hasImage ?  // if has image
               <MyImage />            // return My image tag 
               :
               <OtherElement/>        // otherwise return other element  

             }
        </div>
    )
}

C++ calling base class constructors

The short answer for this is, "because that's what the C++ standard specifies".

Note that you can always specify a constructor that's different from the default, like so:

class Shape  {

  Shape()  {...} //default constructor
  Shape(int h, int w) {....} //some custom constructor


};

class Rectangle : public Shape {
  Rectangle(int h, int w) : Shape(h, w) {...} //you can specify which base class constructor to call

}

The default constructor of the base class is called only if you don't specify which one to call.

How do I prevent DIV tag starting a new line?

You can simply use:

#contentInfo_new br {display:none;}

How to open a link in new tab using angular?

Just add target="_blank" to the

<a mat-raised-button target="_blank" [routerLink]="['/find-post/post', post.postID]"
    class="theme-btn bg-grey white-text mx-2 mb-2">
    Open in New Window
</a>

setSupportActionBar toolbar cannot be applied to (android.widget.Toolbar) error

ToolBar's name can easily be changed using

android:label="My Activity"

in your Manifest File. I just going through Manifest & found

android:label 

Helps to change according to the specific activity, Hope you'll give it a try

How to detect installed version of MS-Office?

        public string WinWordVersion
        {
            get
            {
                string _version = string.Empty;
                Word.Application WinWord = new Word.Application();   

                switch (WinWord.Version.ToString())
                {
                    case "7.0":  _version = "95";
                        break;
                    case "8.0": _version = "97";
                        break;
                    case "9.0": _version = "2000";
                        break;
                    case "10.0": _version = "2002";
                        break;
                    case "11.0":  _version = "2003";
                        break;
                    case "12.0": _version = "2007";
                        break;
                    case "14.0": _version = "2010";
                        break;
                    case "15.0":  _version = "2013";
                        break;
                    case "16.0": _version = "2016";
                        break;
                    default:                            
                        break;
                }

                return WinWord.Caption + " " + _version;
            }
        }

Extract a single (unsigned) integer from a string

Follow this step it will convert string to number

$value = '$0025.123';
$onlyNumeric = filter_var($value, FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_FRACTION);
settype($onlyNumeric,"float");

$result=($onlyNumeric+100);
echo $result;

Another way to do it :

$res = preg_replace("/[^0-9.]/", "", "$15645623.095605659");

fatal error LNK1104: cannot open file 'kernel32.lib'

In Visual Studio 2017, I went to Project Properties -> Configuration Properties -> General, Selected All Platforms (1), then chose the dropdown (2) under Windows SDK Version and updated from 10.0.14393.0 to one that was installed (3). For me, that was 10.0.15063.0.

enter image description here

Additional details: This corrected the error in my case because Windows SDK Version helps VS select the correct paths. VC++ Directories -> Library Directories -> Edit -> Macros -> shows that macro $(WindowsSDK_LibraryPath_x86) has a path with the version number selected above.

Using $window or $location to Redirect in AngularJS

It might help you! demo

AngularJs Code-sample

var app = angular.module('urlApp', []);
app.controller('urlCtrl', function ($scope, $log, $window) {
    $scope.ClickMeToRedirect = function () {
        var url = "http://" + $window.location.host + "/Account/Login";
        $log.log(url);
        $window.location.href = url;
    };
});

HTML Code-sample

<div ng-app="urlApp">
    <div ng-controller="urlCtrl">
        Redirect to <a href="#" ng-click="ClickMeToRedirect()">Click Me!</a>
    </div>
</div>

Mapping many-to-many association table with extra column(s)

As said before, with JPA, in order to have the chance to have extra columns, you need to use two OneToMany associations, instead of a single ManyToMany relationship. You can also add a column with autogenerated values; this way, it can work as the primary key of the table, if useful.

For instance, the implementation code of the extra class should look like that:

@Entity
@Table(name = "USER_SERVICES")
public class UserService{

    // example of auto-generated ID
    @Id
    @Column(name = "USER_SERVICES_ID", nullable = false)
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long userServiceID;



    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "USER_ID")
    private User user;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "SERVICE_ID")
    private Service service;



    // example of extra column
    @Column(name="VISIBILITY")    
    private boolean visibility;



    public long getUserServiceID() {
        return userServiceID;
    }


    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }

    public Service getService() {
        return service;
    }

    public void setService(Service service) {
        this.service = service;
    }

    public boolean getVisibility() {
        return visibility;
    }

    public void setVisibility(boolean visibility) {
        this.visibility = visibility;
    }

}

Why is null an object and what's the difference between null and undefined?

null is an object. Its type is null. undefined is not an object; its type is undefined.

What permission do I need to access Internet from an Android application?

<uses-permission android:name="android.permission.INTERNET" /> 
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>

How to list only files and not directories of a directory Bash?

  • carlpett's find-based answer (find . -maxdepth 1 -type f) works in principle, but is not quite the same as using ls: you get a potentially unsorted list of filenames all prefixed with ./, and you lose the ability to apply ls's many options;
    also find invariably finds hidden items too, whereas ls' behavior depends on the presence or absence of the -a or -A options.

    • An improvement, suggested by Alex Hall in a comment on the question is to combine shell globbing with find:

          find * -maxdepth 0 -type f  # find -L * ... includes symlinks to files
      
      • However, while this addresses the prefix problem and gives you alphabetically sorted output, you still have neither (inline) control over inclusion of hidden items nor access to ls's many other sorting / output-format options.
  • Hans Roggeman's ls + grep answer is pragmatic, but locks you into using long (-l) output format.


To address these limitations I wrote the fls (filtering ls) utility,

  • a utility that provides the output flexibility of ls while also providing type-filtering capability,
  • simply by placing type-filtering characters such as f for files, d for directories, and l for symlinks before a list of ls arguments (run fls --help or fls --man to learn more).

Examples:

fls f        # list all files in current dir.
fls d -tA ~  #  list dirs. in home dir., including hidden ones, most recent first
fls f^l /usr/local/bin/c* # List matches that are files, but not (^) symlinks (l)

Installation

Supported platforms

  • When installing from the npm registry: Linux and macOS
  • When installing manually: any Unix-like platform with Bash

From the npm registry

Note: Even if you don't use Node.js, its package manager, npm, works across platforms and is easy to install; try
curl -L https://git.io/n-install | bash

With Node.js installed, install as follows:

[sudo] npm install fls -g

Note:

  • Whether you need sudo depends on how you installed Node.js / io.js and whether you've changed permissions later; if you get an EACCES error, try again with sudo.

  • The -g ensures global installation and is needed to put fls in your system's $PATH.

Manual installation

  • Download this bash script as fls.
  • Make it executable with chmod +x fls.
  • Move it or symlink it to a folder in your $PATH, such as /usr/local/bin (macOS) or /usr/bin (Linux).

Can I send a ctrl-C (SIGINT) to an application on Windows?

SIGINT can be send to program using windows-kill, by syntax windows-kill -SIGINT PID, where PID can be obtained by Microsoft's pslist.

Regarding catching SIGINTs, if your program is in Python then you can implement SIGINT processing/catching like in this solution.

How to make a <div> or <a href="#"> to align center

You can do this:

<div style="text-align: center">
    <a href="contact.html" class="button large hpbottom">Get Started</a>
</div>

List comprehension on a nested list?

Here is how you would do this with a nested list comprehension:

[[float(y) for y in x] for x in l]

This would give you a list of lists, similar to what you started with except with floats instead of strings. If you want one flat list then you would use [float(y) for x in l for y in x].

How to use mongoose findOne

Use obj[0].nick and you will get desired result,

How do I bind the enter key to a function in tkinter?

Another alternative is to use a lambda:

ent.bind("<Return>", (lambda event: name_of_function()))

Full code:

from tkinter import *
from tkinter.messagebox import showinfo

def reply(name):
    showinfo(title="Reply", message = "Hello %s!" % name)


top = Tk()
top.title("Echo")
top.iconbitmap("Iconshock-Folder-Gallery.ico")

Label(top, text="Enter your name:").pack(side=TOP)
ent = Entry(top)
ent.bind("<Return>", (lambda event: reply(ent.get())))
ent.pack(side=TOP)
btn = Button(top,text="Submit", command=(lambda: reply(ent.get())))
btn.pack(side=LEFT)

top.mainloop()

As you can see, creating a lambda function with an unused variable "event" solves the problem.

Could not install packages due to a "Environment error :[error 13]: permission denied : 'usr/local/bin/f2py'"

Well, in my case the problem had a different cause, the Windows path Length Check this.

I was installing a library on a virtualenv which made the path get longer. As the library was installed, it created some files under site-packages. This made the path exceed Windows limit throwing this error.

Hope it helps someone =)

req.query and req.param in ExpressJS

Passing params

GET request to "/cars/honda" 

returns a list of Honda car models

Passing query

GET request to "/car/honda?color=blue"

returns a list of Honda car models, but filtered so only models with an stock color of blue are returned.

It doesn't make sense to add those filters into the URL parameters (/car/honda/color/blue) because according to REST, that would imply that we want to get a bunch of information about the color "blue". Since what we really want is a filtered list of Honda models, we use query strings to filter down the results that get returned.

Notice that the query strings are really just { key: value } pairs in a slightly different format: ?key1=value1&key2=value2&key3=value3.

CUDA incompatible with my gcc version

Gearoid Murphy's solution works better for me since on my distro (Ubuntu 11.10), gcc-4.4 and gcc-4.6 are in the same directory, so --compiler-bindir is no help. The only caveat is I also had to install g++-4.4 and symlink it as well:

sudo ln -s /usr/bin/gcc-4.4 /usr/local/cuda/bin/gcc
sudo ln -s /usr/bin/g++-4.4 /usr/local/cuda/bin/g++

What is an MDF file?

SQL Server databases use two files - an MDF file, known as the primary database file, which contains the schema and data, and a LDF file, which contains the logs. See wikipedia. A database may also use secondary database file, which normally uses a .ndf extension.

As John S. indicates, these file extensions are purely convention - you can use whatever you want, although I can't think of a good reason to do that.

More info on MSDN here and in Beginning SQL Server 2005 Administation (Google Books) here.

How to get all properties values of a JavaScript Object (without knowing the keys)?

If you really want an array of Values, I find this cleaner than building an array with a for ... in loop.

ECMA 5.1+

function values(o) { return Object.keys(o).map(function(k){return o[k]}) }

It's worth noting that in most cases you don't really need an array of values, it will be faster to do this:

for(var k in o) something(o[k]);

This iterates over the keys of the Object o. In each iteration k is set to a key of o.

Start index for iterating Python list

You can use slicing:

for item in some_list[2:]:
    # do stuff

This will start at the third element and iterate to the end.

Null or empty check for a string variable

Yes, you could also use COALESCE(@value,'')='' which is based on the ANSI SQL standard:

SELECT CASE WHEN COALESCE(@value,'')='' 
    THEN 'Yes, it is null or empty' ELSE 'No, not null or empty' 
    END AS IsNullOrEmpty

DEMO

How to change Tkinter Button state from disabled to normal?

This is what worked for me. I am not sure why the syntax is different, But it was extremely frustrating trying every combination of activate, inactive, deactivated, disabled, etc. In lower case upper case in quotes out of quotes in brackets out of brackets etc. Well, here's the winning combination for me, for some reason.. different than everyone else?

import tkinter

class App(object):
    def __init__(self):
        self.tree = None
        self._setup_widgets()

    def _setup_widgets(self):
        butts = tkinter.Button(text = "add line", state="disabled")
        butts.grid()

def main():  
    root = tkinter.Tk()
    app = App()
    root.mainloop()

if __name__ == "__main__":
    main()

PHP Convert String into Float/Double

If the function floatval does not work you can try to make this :

    $string = "2968789218";
    $float = $string * 1.0;
    echo $float;

But for me all the previous answer worked ( try it in http://writecodeonline.com/php/ ) Maybe the problem is on your server ?

What is middleware exactly?

Wikipedia has a quite good explanation: http://en.wikipedia.org/wiki/Middleware

It starts with

Middleware is computer software that connects software components or applications. The software consists of a set of services that allows multiple processes running on one or more machines to interact.

What is Middleware gives a few examples.

Combine two columns and add into one new column

Generally, I agree with @kgrittn's advice. Go for it.

But to address your basic question about concat(): The new function concat() is useful if you need to deal with null values - and null has neither been ruled out in your question nor in the one you refer to.

If you can rule out null values, the good old (SQL standard) concatenation operator || is still the best choice, and @luis' answer is just fine:

SELECT col_a || col_b;

If either of your columns can be null, the result would be null in that case. You could defend with COALESCE:

SELECT COALESCE(col_a, '') || COALESCE(col_b, '');

But that get tedious quickly with more arguments. That's where concat() comes in, which never returns null, not even if all arguments are null. Per documentation:

NULL arguments are ignored.

SELECT concat(col_a, col_b);

The remaining corner case for both alternatives is where all input columns are null in which case we still get an empty string '', but one might want null instead (at least I would). One possible way:

SELECT CASE
          WHEN col_a IS NULL THEN col_b
          WHEN col_b IS NULL THEN col_a
          ELSE col_a || col_b
       END;

This gets more complex with more columns quickly. Again, use concat() but add a check for the special condition:

SELECT CASE WHEN (col_a, col_b) IS NULL THEN NULL
            ELSE concat(col_a, col_b) END;

How does this work?
(col_a, col_b) is shorthand notation for a row type expression ROW (col_a, col_b). And a row type is only null if all columns are null. Detailed explanation:

Also, use concat_ws() to add separators between elements (ws for "with separator").


An expression like the one in Kevin's answer:

SELECT $1.zipcode || ' - ' || $1.city || ', ' || $1.state;

is tedious to prepare for null values in PostgreSQL 8.3 (without concat()). One way (of many):

SELECT COALESCE(
         CASE
            WHEN $1.zipcode IS NULL THEN $1.city
            WHEN $1.city    IS NULL THEN $1.zipcode
            ELSE $1.zipcode || ' - ' || $1.city
         END, '')
       || COALESCE(', ' || $1.state, '');

Function volatility is only STABLE

concat() and concat_ws() are STABLE functions, not IMMUTABLE because they can invoke datatype output functions (like timestamptz_out) that depend on locale settings.
Explanation by Tom Lane.

This prohibits their direct use in index expressions. If you know that the result is actually immutable in your case, you can work around this with an IMMUTABLE function wrapper. Example here:

How to convert JSON data into a Python object

The answers given here does not return the correct object type, hence I created these methods below. They also fail if you try to add more fields to the class that does not exist in the given JSON:

def dict_to_class(class_name: Any, dictionary: dict) -> Any:
    instance = class_name()
    for key in dictionary.keys():
        setattr(instance, key, dictionary[key])
    return instance


def json_to_class(class_name: Any, json_string: str) -> Any:
    dict_object = json.loads(json_string)
    return dict_to_class(class_name, dict_object)

How to use a Bootstrap 3 glyphicon in an html select

I ended up using the bootstrap 3 dropdown button, I'm posting my solution here in case it helps someone in future. Adding the bootstrap 3 list-inline to the class for the ul causes it to display in a nicely compact format as well.

<div class="btn-group">
    <button type="button" class="btn btn-default dropdown-toggle" data-toggle="dropdown">
        Select icon <span class="caret"></span>
    </button>
    <ul class="dropdown-menu list-inline" role="menu">
        <li><span class="glyphicon glyphicon-cutlery"></span></li>
        <li><span class="glyphicon glyphicon-fire"></span></li>
        <li><span class="glyphicon glyphicon-glass"></span></li>
        <li><span class="glyphicon glyphicon-heart"></span></li>          
    </ul>
</div>

I'm using Angular.js so this is the actual code I used:

<div class="btn-group">
            <button type="button" class="btn btn-default dropdown-toggle" data-toggle="dropdown">
                Avatar <span class="caret"></span>
            </button>
            <ul class="dropdown-menu list-inline" role="menu">
                <li ng-repeat="avatar in avatars" ng-click="avatarSelected(avatar)">
                    <span ng-class="getAvatar(avatar)"></span>
                </li>
            </ul>
        </div>

And in my controller:

$scope.avatars=['cutlery','eye-open','flag','flash','glass','fire','hand-right','heart','heart-empty','leaf','music','send','star','star-empty','tint','tower','tree-conifer','tree-deciduous','usd','user','wrench','time','road','cloud'];

$scope.getAvatar=function(avatar){
     return 'glyphicon glyphicon-'+avatar;
};

How to list files and folder in a dir (PHP)

If you have problems with accessing to the path, maybe you need to put this:

$root = $_SERVER['DOCUMENT_ROOT'];
$path = "/cv/"; 

// Open the folder
 $dir_handle = @opendir($root . $path) or die("Unable to open $path");

Android emulator doesn't take keyboard input - SDK tools rev 20

Update

As of SDK rev 21 the Android Virtual Device Manager has an improved UI which resolves this issue. I have highlighted some of the more important configuration settings below:

enter image description here

If you notice that the soft (screen-based) main keys Back, Home, etc. are missing from your emulator you can set hw.mainKeys=no to enable them.

enter image description here

Original answer

Even though the developer documentation says keyboard support is enabled by default it doesn't seem to be that way in SDK rev 20. I explicitly enabled keyboard support in my emulator's config.ini file and that worked!

Add: hw.keyboard=yes

To: ~/.android/avd/<emulator-device-name>.avd/config.ini

Similarly, add hw.dPad=yes if you wish to use the arrow-keys to navigate the application list.

Reference: http://developer.android.com/tools/devices/managing-avds-cmdline.html#hardwareopts

On Mac OS and Linux you can edit all of your emulator configurations with one Terminal command:

for f in ~/.android/avd/*.avd/config.ini; do echo 'hw.keyboard=yes' >> "$f"; done


On a related note, if your tablet emulator is missing the BACK/HOME buttons, try selecting WXGA800 as the Built-in skin in the AVD editor: enter image description here

Or by manually setting the skin in config.ini:

skin.name=WXGA800
skin.path=platforms/android-16/skins/WXGA800

(example is for API 16)

How to use npm with ASP.NET Core

Shawn Wildermuth has a nice guide here: https://wildermuth.com/2017/11/19/ASP-NET-Core-2-0-and-the-End-of-Bower

The article links to the gulpfile on GitHub where he's implemented the strategy in the article. You could just copy and paste most of the gulpfile contents into yours, but be sure to add the appropriate packages in package.json under devDependencies: gulp gulp-uglify gulp-concat rimraf merge-stream

What is for Python what 'explode' is for PHP?

Choose one you need:

>>> s = "Rajasekar SP  def"
>>> s.split(' ')
['Rajasekar', 'SP', '', 'def']
>>> s.split()
['Rajasekar', 'SP', 'def']
>>> s.partition(' ')
('Rajasekar', ' ', 'SP  def')

str.split and str.partition

How do I update a model value in JavaScript in a Razor view?

You could use jQuery and an Ajax call to post the specific update back to your server with Javascript.

It would look something like this:

function updatePostID(val, comment)
{

    var args = {};
    args.PostID = val;
    args.Comment = comment;

    $.ajax({
     type: "POST",
     url: controllerActionMethodUrlHere,
     contentType: "application/json; charset=utf-8",
     data: args,
     dataType: "json",
     success: function(msg) 
     {
        // Something afterwards here

     }
    });

}

Enable remote MySQL connection: ERROR 1045 (28000): Access denied for user

MySQL ODBC 3.51 Driver is that special characters in the password aren't handled.

"Warning – You might have a serious headache with MySQL ODBC 3.51 if the password in your GRANT command contains special characters, such as ! @ # $ % ^ ?. MySQL ODBC 3.51 ODBC Driver does not support these special characters in the password box. The only error message you would receive is “Access denied” (using password: YES)" - from http://www.plaintutorials.com/install-and-create-mysql-odbc-connector-on-windows-7/

Mockito. Verify method arguments

  • You don't need the eq matcher if you don't use other matchers.
  • You are not using the correct syntax - your method call should be outside the .verify(mock). You are now initiating verification on the result of the method call, without verifying anything (not making a method call). Hence all tests are passing.

You code should look like:

Mockito.verify(mock).mymethod(obj);
Mockito.verify(mock).mymethod(null);
Mockito.verify(mock).mymethod("something_else");

Declare variable MySQL trigger

All DECLAREs need to be at the top. ie.

delimiter //

CREATE TRIGGER pgl_new_user 
AFTER INSERT ON users FOR EACH ROW
BEGIN
    DECLARE m_user_team_id integer;
    DECLARE m_projects_id integer;
    DECLARE cur CURSOR FOR SELECT project_id FROM user_team_project_relationships WHERE user_team_id = m_user_team_id;

    SET @m_user_team_id := (SELECT id FROM user_teams WHERE name = "pgl_reporters");

    OPEN cur;
        ins_loop: LOOP
            FETCH cur INTO m_projects_id;
            IF done THEN
                LEAVE ins_loop;
            END IF;
            INSERT INTO users_projects (user_id, project_id, created_at, updated_at, project_access) 
            VALUES (NEW.id, m_projects_id, now(), now(), 20);
        END LOOP;
    CLOSE cur;
END//

How do I display a decimal value to 2 decimal places?

decimalVar.ToString("F");

This will:

  • Round off to 2 decimal places eg. 23.456 ? 23.46
  • Ensure that there are always 2 decimal places eg. 23 ? 23.00; 12.5 ? 12.50

Ideal for displaying currency.

Check out the documentation on ToString("F") (thanks to Jon Schneider).

How do I call a SQL Server stored procedure from PowerShell?

Use sqlcmd instead of osql if it's a 2005 database

How do I find the current directory of a batch file, and then use it for the path?

There is no need to know where the files are, because when you launch a bat file the working directory is the directory where it was launched (the "master folder"), so if you have this structure:

.\mydocuments\folder\mybat.bat
.\mydocuments\folder\subfolder\file.txt

And the user starts the "mybat.bat", the working directory is ".\mydocuments\folder", so you only need to write the subfolder name in your script:

@Echo OFF
REM Do anything with ".\Subfolder\File1.txt"
PUSHD ".\Subfolder"
Type "File1.txt"
Pause&Exit

Anyway, the working directory is stored in the "%CD%" variable, and the directory where the bat was launched is stored on the argument 0. Then if you want to know the working directory on any computer you can do:

@Echo OFF
Echo Launch dir: "%~dp0"
Echo Current dir: "%CD%"
Pause&Exit

Spark: Add column to dataframe conditionally

How about something like this?

val newDF = df.filter($"B" === "").take(1) match {
  case Array() => df
  case _ => df.withColumn("D", $"B" === "")
}

Using take(1) should have a minimal hit

How to get response from S3 getObject in Node.js?

At first glance it doesn't look like you are doing anything wrong but you don't show all your code. The following worked for me when I was first checking out S3 and Node:

var AWS = require('aws-sdk');

if (typeof process.env.API_KEY == 'undefined') {
    var config = require('./config.json');
    for (var key in config) {
        if (config.hasOwnProperty(key)) process.env[key] = config[key];
    }
}

var s3 = new AWS.S3({accessKeyId: process.env.AWS_ID, secretAccessKey:process.env.AWS_KEY});
var objectPath = process.env.AWS_S3_FOLDER +'/test.xml';
s3.putObject({
    Bucket: process.env.AWS_S3_BUCKET, 
    Key: objectPath,
    Body: "<rss><data>hello Fred</data></rss>",
    ACL:'public-read'
}, function(err, data){
    if (err) console.log(err, err.stack); // an error occurred
    else {
        console.log(data);           // successful response
        s3.getObject({
            Bucket: process.env.AWS_S3_BUCKET, 
            Key: objectPath
        }, function(err, data){
            console.log(data.Body.toString());
        });
    }
});

Invalid CSRF Token 'null' was found on the request parameter '_csrf' or header 'X-CSRF-TOKEN'

It looks like the CSRF (Cross Site Request Forgery) protection in your Spring application is enabled. Actually it is enabled by default.

According to spring.io:

When should you use CSRF protection? Our recommendation is to use CSRF protection for any request that could be processed by a browser by normal users. If you are only creating a service that is used by non-browser clients, you will likely want to disable CSRF protection.

So to disable it:

@Configuration
public class RestSecurityConfig extends WebSecurityConfigurerAdapter {
  @Override
  protected void configure(HttpSecurity http) throws Exception {
    http.csrf().disable();
  }
}

If you want though to keep CSRF protection enabled then you have to include in your form the csrftoken. You can do it like this:

<form .... >
  ....other fields here....
  <input type="hidden"  name="${_csrf.parameterName}"   value="${_csrf.token}"/>
</form>

You can even include the CSRF token in the form's action:

<form action="./upload?${_csrf.parameterName}=${_csrf.token}" method="post" enctype="multipart/form-data">

Return only string message from Spring MVC 3 Controller

Annotate your method in controller with @ResponseBody:

@RequestMapping(value="/controller", method=GET)
@ResponseBody
public String foo() {
    return "Response!";
}

From: 15.3.2.6 Mapping the response body with the @ResponseBody annotation:

The @ResponseBody annotation [...] can be put on a method and indicates that the return type should be written straight to the HTTP response body (and not placed in a Model, or interpreted as a view name).

Eclipse projects not showing up after placing project files in workspace/projects

I have tried many of the option suggested but at last importing project in new workspace solved my problem.

I think there is some problem in metadata files in old workspace.

How to stop event bubbling on checkbox click

Here's a trick that worked for me:

handleClick = e => {
    if (e.target === e.currentTarget) {
        // do something
    } else {
        // do something else
    }
}

Explanation: I attached handleClick to a backdrop of a modal window, but it also fired on every click inside of a modal window (because it was IN the backdrop div). So I added the condition (e.target === e.currentTarget), which is only fulfilled when a backdrop is clicked.

What data type to use for money in Java?

You can use Money and Currency API (JSR 354). You can use this API in, provided you add appropriate dependencies to your project.

For Java 8, add the following reference implementation as a dependency to your pom.xml:

<dependency>
    <groupId>org.javamoney</groupId>
    <artifactId>moneta</artifactId>
    <version>1.0</version>
</dependency>

This dependency will transitively add javax.money:money-api as a dependency.

You can then use the API:

package com.example.money;

import static org.junit.Assert.assertThat;
import static org.hamcrest.CoreMatchers.is;

import java.util.Locale;

import javax.money.Monetary;
import javax.money.MonetaryAmount;
import javax.money.MonetaryRounding;
import javax.money.format.MonetaryAmountFormat;
import javax.money.format.MonetaryFormats;

import org.junit.Test;

public class MoneyTest {

    @Test
    public void testMoneyApi() {
        MonetaryAmount eurAmount1 = Monetary.getDefaultAmountFactory().setNumber(1.1111).setCurrency("EUR").create();
        MonetaryAmount eurAmount2 = Monetary.getDefaultAmountFactory().setNumber(1.1141).setCurrency("EUR").create();

        MonetaryAmount eurAmount3 = eurAmount1.add(eurAmount2);
        assertThat(eurAmount3.toString(), is("EUR 2.2252"));

        MonetaryRounding defaultRounding = Monetary.getDefaultRounding();
        MonetaryAmount eurAmount4 = eurAmount3.with(defaultRounding);
        assertThat(eurAmount4.toString(), is("EUR 2.23"));

        MonetaryAmountFormat germanFormat = MonetaryFormats.getAmountFormat(Locale.GERMAN);
        assertThat(germanFormat.format(eurAmount4), is("EUR 2,23") );
    }
}

What is the most efficient way to get first and last line of a text file?

Here is an extension of @Trasp's answer that has additional logic for handling the corner case of a file that has only one line. It may be useful to handle this case if you repeatedly want to read the last line of a file that is continuously being updated. Without this, if you try to grab the last line of a file that has just been created and has only one line, IOError: [Errno 22] Invalid argument will be raised.

def tail(filepath):
    with open(filepath, "rb") as f:
        first = f.readline()      # Read the first line.
        f.seek(-2, 2)             # Jump to the second last byte.
        while f.read(1) != b"\n": # Until EOL is found...
            try:
                f.seek(-2, 1)     # ...jump back the read byte plus one more.
            except IOError:
                f.seek(-1, 1)
                if f.tell() == 0:
                    break
        last = f.readline()       # Read last line.
    return last

Inserting values into tables Oracle SQL

You can insert into a table from a SELECT.

INSERT INTO
  Employee (emp_id, emp_name, emp_address, emp_state, emp_position, emp_manager)
SELECT
  001,
  'John Doe',
  '1 River Walk, Green Street',
  (SELECT id FROM state WHERE name = 'New York'),
  (SELECT id FROM positions WHERE name = 'Sales Executive'),
  (SELECT id FROM manager WHERE name = 'Barry Green')
FROM
  dual

Or, similarly...

INSERT INTO
  Employee (emp_id, emp_name, emp_address, emp_state, emp_position, emp_manager)
SELECT
  001,
  'John Doe',
  '1 River Walk, Green Street',
  state.id,
  positions.id,
  manager.id
FROM
  state
CROSS JOIN
  positions
CROSS JOIN
  manager
WHERE
      state.name     = 'New York'
  AND positions.name = 'Sales Executive'
  AND manager.name   = 'Barry Green'

Though this one does assume that all the look-ups exist. If, for example, there is no position name 'Sales Executive', nothing would get inserted with this version.

Stopping python using ctrl+c

The interrupt process is hardware and OS dependent. So you will have very different behavior depending on where you run your python script. For example, on Windows machines we have Ctrl+C (SIGINT) and Ctrl+Break (SIGBREAK).

So while SIGINT is present on all systems and can be handled and caught, the SIGBREAK signal is Windows specific (and can be disabled in CONFIG.SYS) and is really handled by the BIOS as an interrupt vector INT 1Bh, which is why this key is much more powerful than any other. So if you're using some *nix flavored OS, you will get different results depending on the implementation, since that signal is not present there, but others are. In Linux you can check what signals are available to you by:

$ kill -l
 1) SIGHUP       2) SIGINT       3) SIGQUIT      4) SIGILL       5) SIGTRAP
 6) SIGABRT      7) SIGEMT       8) SIGFPE       9) SIGKILL     10) SIGBUS
11) SIGSEGV     12) SIGSYS      13) SIGPIPE     14) SIGALRM     15) SIGTERM
16) SIGURG      17) SIGSTOP     18) SIGTSTP     19) SIGCONT     20) SIGCHLD
21) SIGTTIN     22) SIGTTOU     23) SIGIO       24) SIGXCPU     25) SIGXFSZ
26) SIGVTALRM   27) SIGPROF     28) SIGWINCH    29) SIGPWR      30) SIGUSR1
31) SIGUSR2     32) SIGRTMAX

So if you want to catch the CTRL+BREAK signal on a linux system you'll have to check to what POSIX signal they have mapped that key. Popular mappings are:

CTRL+\     = SIGQUIT 
CTRL+D     = SIGQUIT
CTRL+C     = SIGINT
CTRL+Z     = SIGTSTOP 
CTRL+BREAK = SIGKILL or SIGTERM or SIGSTOP

In fact, many more functions are available under Linux, where the SysRq (System Request) key can take on a life of its own...

Create unique constraint with null columns

You can store favourites with no associated menu in a separate table:

CREATE TABLE FavoriteWithoutMenu
(
  FavoriteWithoutMenuId uuid NOT NULL, --Primary key
  UserId uuid NOT NULL,
  RecipeId uuid NOT NULL,
  UNIQUE KEY (UserId, RecipeId)
)

Getting only response header from HTTP POST using curl

While the other answers have not worked for me in all situations, the best solution I could find (working with POST as well), taken from here:

curl -vs 'https://some-site.com' 1> /dev/null

Read from file in eclipse

I am using eclipse and I was stuck on not being able to read files because of a "file not found exception". What I did to solve this problem was I moved the file to the root of my project. Hope this helps.

HTML / CSS How to add image icon to input type="button"?

If you're using spritesheets this becomes impossible and the element must be wrapped.

.btn{
    display: inline-block;
    background: blue;
    position: relative;
    border-radius: 5px;
}
.input, .btn:after{
    color: #fff;
}
.btn:after{
    position: absolute;
    content: '@';
    right: 0;
    width: 1.3em;
    height: 1em;
}
.input{
    background: transparent;
    color: #fff;
    border: 0;
    padding-right: 20px;
    cursor: pointer;
    position: relative;
    padding: 5px 20px 5px 5px;
    z-index: 1;
}

Check out this fiddle: http://jsfiddle.net/AJNnZ/

docker error - 'name is already in use by container'

You have 2 options to fix this...

  1. Remove previous container using that name, with the command docker rm $(docker ps -aq --filter name=myContainerName)

    OR

  2. Rename current container to a different name i.e change this portion --name registry-v1 to something like --name myAnotherContainerName

You are getting this error because that container name ( i.e registry-v1) was used by another container in the past...even though that container may have exited i.e (currently not in use).

How to solve the “failed to lazily initialize a collection of role” Hibernate exception

Hi All posting quite late hope it helps others, Thanking in advance to @GMK for this post Hibernate.initialize(object)

when Lazy="true"

Set<myObject> set=null;
hibernateSession.open
set=hibernateSession.getMyObjects();
hibernateSession.close();

now if i access 'set' after closing session it throws exception.

My solution :

Set<myObject> set=new HashSet<myObject>();
hibernateSession.open
set.addAll(hibernateSession.getMyObjects());
hibernateSession.close();

now i can access 'set' even after closing Hibernate Session.

How to get the indices list of all NaN value in numpy array?

Since x!=x returns the same boolean array with np.isnan(x) (because np.nan!=np.nan would return True), you could also write:

np.argwhere(x!=x)

However, I still recommend writing np.argwhere(np.isnan(x)) since it is more readable. I just try to provide another way to write the code in this answer.

Find size of object instance in bytes in c#

This is impossible to do at runtime.

There are various memory profilers that display object size, though.

EDIT: You could write a second program that profiles the first one using the CLR Profiling API and communicates with it through remoting or something.

How to get character for a given ascii value

Simply Try this:

int n = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("data is: {0}", Convert.ToChar(n));

Maintaining the final state at end of a CSS3 animation

Try adding animation-fill-mode: forwards;. For example like this:

-webkit-animation: bubble 1.0s forwards; /* for less modern browsers */
        animation: bubble 1.0s forwards;

What is the Java equivalent of PHP var_dump?

Just to addup on the Field solution (the setAccessible) so that you can access private variable of an object:

public static void dd(Object obj) throws IllegalArgumentException, IllegalAccessException {
    Field[] fields = obj.getClass().getDeclaredFields();
    for (int i=0; i<fields.length; i++)
    {
        fields[i].setAccessible(true);
        System.out.println(fields[i].getName() + " - " + fields[i].get(obj));
    } 

}

What is an NP-complete in computer science?

I have heard an explanation, that is:" NP-Completeness is probably one of the more enigmatic ideas in the study of algorithms. "NP" stands for "nondeterministic polynomial time," and is the name for what is called a complexity class to which problems can belong. The important thing about the NP complexity class is that problems within that class can be verified by a polynomial time algorithm. As an example, consider the problem of counting stuff. Suppose there are a bunch of apples on a table. The problem is "How many apples are there?" You are provided with a possible answer, 8. You can verify this answer in polynomial time by using the algorithm of, duh, counting the apples. Counting the apples happens in O(n) (that's Big-oh notation) time, because it takes one step to count each apple. For n apples, you need n steps. This problem is in the NP complexity class.

A problem is classified as NP-complete if it can be shown that it is both NP-Hard and verifiable in polynomial time. Without going too deeply into the discussion of NP-Hard, suffice it to say that there are certain problems to which polynomial time solutions have not been found. That is, it takes something like n! (n factorial) steps to solve them. However, if you're given a solution to an NP-Complete problem, you can verify it in polynomial time.

A classic example of an NP-Complete problem is The Traveling Salesman Problem."

The author: ApoxyButt From: http://www.everything2.com/title/NP-complete

How do I grant myself admin access to a local SQL Server instance?

Open a command prompt window. If you have a default instance of SQL Server already running, run the following command on the command prompt to stop the SQL Server service:

net stop mssqlserver

Now go to the directory where SQL server is installed. The directory can for instance be one of these:

C:\Program Files\Microsoft SQL Server\MSSQL10_50.MSSQLSERVER\MSSQL\Binn
C:\Program Files\Microsoft SQL Server\MSSQL13.MSSQLSERVER\MSSQL\Binn

Figure out your MSSQL directory and CD into it as such:

CD C:\Program Files\Microsoft SQL Server\MSSQL10_50.MSSQLSERVER\MSSQL\Binn

Now run the following command to start SQL Server in single user mode. As SQLCMD is being specified, only one SQLCMD connection can be made (from another command prompt window).

sqlservr -m"SQLCMD"

Now, open another command prompt window as the same user as the one that started SQL Server in single user mode above, and in it, run:

sqlcmd

And press enter. Now you can execute SQL statements against the SQL Server instance running in single user mode:

create login [<<DOMAIN\USERNAME>>] from windows;

-- For older versions of SQL Server:
EXEC sys.sp_addsrvrolemember @loginame = N'<<DOMAIN\USERNAME>>', @rolename = N'sysadmin';

-- For newer versions of SQL Server:
ALTER SERVER ROLE [sysadmin] ADD MEMBER [<<DOMAIN\USERNAME>>];

GO

Source.

UPDATED Do not forget a semicolon after ALTER SERVER ROLE [sysadmin] ADD MEMBER [<<DOMAIN\USERNAME>>]; and do not add extra semicolon after GO or the command never executes.

iOS9 Untrusted Enterprise Developer with no option to trust

For iOS 9 beta 3,4 users. Since the option to view profiles is not viewable do the following from Xcode.

  1. Open Xcode 7.
  2. Go to window, devices.
  3. Select your device.
  4. Delete all of the profiles loaded on the device.
  5. Delete the old app on your device.
  6. Clean and rebuild the app to your device.

On iOS 9.1+ n iOS 9.2+ go to Settings -> General -> Device Management -> press the Profile -> Press Trust.

How to run a PowerShell script

You can run from cmd like this:

type "script_path" | powershell.exe -c -

How to convert Java String to JSON Object

Your json -

{
    "title":"Free Music Archive - Genres",
    "message":"",
    "errors":[
    ],
    "total":"163",
    "total_pages":82,
    "page":1,
    "limit":"2",
    "dataset":[
    {
    "genre_id":"1",
    "genre_parent_id":"38",
    "genre_title":"Avant-Garde",
    "genre_handle":"Avant-Garde",
    "genre_color":"#006666"
    },
    {
    "genre_id":"2",
    "genre_parent_id":null,
    "genre_title":"International",
    "genre_handle":"International",
    "genre_color":"#CC3300"
    }
    ]
    }

Using the JSON library from json.org -

JSONObject o = new JSONObject(jsonString);

NOTE:

The following information will be helpful to you - json.org.

UPDATE:

import org.json.JSONObject;
 //Other lines of code
URL seatURL = new URL("http://freemusicarchive.org/
 api/get/genres.json?api_key=60BLHNQCAOUFPIBZ&limit=2");
 //Return the JSON Response from the API
 BufferedReader br = new BufferedReader(new         
 InputStreamReader(seatURL.openStream(),
 Charset.forName("UTF-8")));
 String readAPIResponse = " ";
 StringBuilder jsonString = new StringBuilder();
 while((readAPIResponse = br.readLine()) != null){
   jsonString.append(readAPIResponse);
 }
 JSONObject jsonObj = new JSONObject(jsonString.toString());
 System.out.println(jsonString);
 System.out.println("---------------------------");
 System.out.println(jsonObj);

Easiest way to open a download window without navigating away from the page

I've been looking for a good way to use javascript to initiate the download of a file, just as this question suggests. However these answers not been helpful. I then did some xbrowser testing and have found that an iframe works best on all modern browsers IE>8.

downloadUrl = "http://example.com/download/file.zip";
var downloadFrame = document.createElement("iframe"); 
downloadFrame.setAttribute('src',downloadUrl);
downloadFrame.setAttribute('class',"screenReaderText"); 
document.body.appendChild(downloadFrame); 

class="screenReaderText" is my class to style content that is present but not viewable.

css:

.screenReaderText { 
  border: 0; 
  clip: rect(0 0 0 0); 
  height: 1px; 
  margin: -1px; 
  overflow: hidden; 
  padding: 0; 
  position: absolute; 
  width: 1px; 
}

same as .visuallyHidden in html5boilerplate

I prefer this to the javascript window.open method because if the link is broken the iframe method simply doesn't do anything as opposed to redirecting to a blank page saying the file could not be opened.

window.open(downloadUrl, 'download_window', 'toolbar=0,location=no,directories=0,status=0,scrollbars=0,resizeable=0,width=1,height=1,top=0,left=0');
window.focus();