How to programmatically close a JFrame
Not only to close the JFrame but also to trigger WindowListener events, try this:
myFrame.dispatchEvent(new WindowEvent(myFrame, WindowEvent.WINDOW_CLOSING));
How to specify 64 bit integers in c
Use int64_t
, that portable C99 code.
int64_t var = 0x0000444400004444LL;
For printing:
#define __STDC_FORMAT_MACROS
#include <inttypes.h>
printf("blabla %" PRIi64 " blabla\n", var);
How can I detect if a selector returns null?
The selector returns an array of jQuery objects. If no matching elements are found, it returns an empty array. You can check the .length
of the collection returned by the selector or check whether the first array element is 'undefined'.
You can use any the following examples inside an IF statement and they all produce the same result. True, if the selector found a matching element, false otherwise.
$('#notAnElement').length > 0
$('#notAnElement').get(0) !== undefined
$('#notAnElement')[0] !== undefined
How to get first element in a list of tuples?
You can use "tuple unpacking":
>>> my_list = [(1, 'abc'), (2, 'def')]
>>> my_ids = [idx for idx, val in my_list]
>>> my_ids
[1, 2]
At iteration time each tuple is unpacked and its values are set to the variables idx
and val
.
>>> x = (1, 'abc')
>>> idx, val = x
>>> idx
1
>>> val
'abc'
Foreach value from POST from form
First, please do not use extract(), it can be a security problem because it is easy to manipulate POST parameters
In addition, you don't have to use variable variable names (that sounds odd), instead:
foreach($_POST as $key => $value) {
echo "POST parameter '$key' has '$value'";
}
To ensure that you have only parameters beginning with 'item_name' you can check it like so:
$param_name = 'item_name';
if(substr($key, 0, strlen($param_name)) == $param_name) {
// do something
}
How can I get the data type of a variable in C#?
There is an important and subtle issue that none of them addresses directly. There are two ways of considering type in C#: static type and run-time type.
Static type is the type of a variable in your source code. It is therefore a compile-time concept. This is the type that you see in a tooltip when you hover over a variable or property in your development environment.
You can obtain static type by writing helper generic method to let type inference take care of it for you:
Type GetStaticType<T>(T x) { return typeof(T); }
Run-time type is the type of an object in memory. It is therefore a run-time concept. This is the type returned by the GetType()
method.
An object's run-time type is frequently different from the static type of the variable, property, or method that holds or returns it. For example, you can have code like this:
object o = "Some string";
The static type of the variable is object
, but at run time, the type of the variable's referent is string
. Therefore, the next line will print "System.String" to the console:
Console.WriteLine(o.GetType()); // prints System.String
But, if you hover over the variable o
in your development environment, you'll see the type System.Object
(or the equivalent object
keyword). You also see the same using our helper function from above:
Console.WriteLine(GetStaticType(o)); // prints System.Object
For value-type variables, such as int
, double
, System.Guid
, you know that the run-time type will always be the same as the static type, because value types cannot serve as the base class for another type; the value type is guaranteed to be the most-derived type in its inheritance chain. This is also true for sealed reference types: if the static type is a sealed reference type, the run-time value must either be an instance of that type or null
.
Conversely, if the static type of the variable is an abstract type, then it is guaranteed that the static type and the runtime type will be different.
To illustrate that in code:
// int is a value type
int i = 0;
// Prints True for any value of i
Console.WriteLine(i.GetType() == typeof(int));
// string is a sealed reference type
string s = "Foo";
// Prints True for any value of s
Console.WriteLine(s == null || s.GetType() == typeof(string));
// object is an unsealed reference type
object o = new FileInfo("C:\\f.txt");
// Prints False, but could be true for some values of o
Console.WriteLine(o == null || o.GetType() == typeof(object));
// FileSystemInfo is an abstract type
FileSystemInfo fsi = new DirectoryInfo("C:\\");
// Prints False for all non-null values of fsi
Console.WriteLine(fsi == null || fsi.GetType() == typeof(FileSystemInfo));
How to stop/shut down an elasticsearch node?
The Head plugin for Elasticsearch provides a great web based front end for Elasticsearch administration, including shutting down nodes. It can run any Elasticsearch commands as well.
Call a function from another file?
First of all you do not need a .py
.
If you have a file a.py
and inside you have some functions:
def b():
# Something
return 1
def c():
# Something
return 2
And you want to import them in z.py
you have to write
from a import b, c
Prompt Dialog in Windows Forms
Add reference to Microsoft.VisualBasic
and use this into your C# code:
string input = Microsoft.VisualBasic.Interaction.InputBox("Prompt",
"Title",
"Default",
0,
0);
To add the refernce: right-click on the References in your Project Explorer window then on Add Reference, and check VisualBasic from that list.
Initialize Array of Objects using NSArray
There is also a shorthand of doing this:
NSArray *persons = @[person1, person2, person3];
It's equivalent to
NSArray *persons = [NSArray arrayWithObjects:person1, person2, person3, nil];
As iiFreeman said, you still need to do proper memory management if you're not using ARC.
How to Configure SSL for Amazon S3 bucket
It is not possible directly with S3, but you can create a Cloud Front distribution from you bucket. Then go to certificate manager and request a certificate. Amazon gives them for free. Ones you have successfully confirmed the certification, assign it to your Cloud Front distribution. Also remember to set the rule to re-direct http to https.
I'm hosting couple of static websites on Amazon S3, like my personal website to which I have assigned the SSL certificate as they have the Cloud Front distribution.
Response::json() - Laravel 5.1
From a controller you can also return an Object/Array and it will be sent as a JSON response (including the correct HTTP headers).
public function show($id)
{
return Customer::find($id);
}
Regex pattern inside SQL Replace function?
I think a simpler and faster approach is iterate by each character of the alphabet:
DECLARE @i int
SET @i = 0
WHILE(@i < 256)
BEGIN
IF char(@i) NOT IN ('0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '.')
UPDATE Table SET Column = replace(Column, char(@i), '')
SET @i = @i + 1
END
How do you programmatically set an attribute?
setattr(x, attr, 'magic')
For help on it:
>>> help(setattr)
Help on built-in function setattr in module __builtin__:
setattr(...)
setattr(object, name, value)
Set a named attribute on an object; setattr(x, 'y', v) is equivalent to
``x.y = v''.
Edit: However, you should note (as pointed out in a comment) that you can't do that to a "pure" instance of object
. But it is likely you have a simple subclass of object where it will work fine. I would strongly urge the O.P. to never make instances of object like that.
How to redirect to another page using PHP
Assuming you're using cookies for login, just call it after your setcookie
call -- after all, you must be calling that one before any output too.
Anyway in general you could check for the presence of your form's submit button name at the beginning of the script, do your logic, and then output stuff:
if(isset($_POST['mySubmit'])) {
// the form was submitted
// ...
// perform your logic
// redirect if login was successful
header('Location: /somewhere');
}
// output your stuff here
Is there a JSON equivalent of XQuery/XPath?
If you're like me and you just want to do path-based lookups, but don't care about real XPath, lodash's _.get()
can work. Example from lodash docs:
var object = { 'a': [{ 'b': { 'c': 3 } }] };
_.get(object, 'a[0].b.c');
// ? 3
_.get(object, ['a', '0', 'b', 'c']);
// ? 3
_.get(object, 'a.b.c', 'default');
// ? 'default'
Method call if not null in C#
A quick extension method:
public static void IfNotNull<T>(this T obj, Action<T> action, Action actionIfNull = null) where T : class {
if(obj != null) {
action(obj);
} else if ( actionIfNull != null ) {
actionIfNull();
}
}
example:
string str = null;
str.IfNotNull(s => Console.Write(s.Length));
str.IfNotNull(s => Console.Write(s.Length), () => Console.Write("null"));
or alternatively:
public static TR IfNotNull<T, TR>(this T obj, Func<T, TR> func, Func<TR> ifNull = null) where T : class {
return obj != null ? func(obj) : (ifNull != null ? ifNull() : default(TR));
}
example:
string str = null;
Console.Write(str.IfNotNull(s => s.Length.ToString());
Console.Write(str.IfNotNull(s => s.Length.ToString(), () => "null"));
How to display PDF file in HTML?
I've had something similar before and used normally tags
<a href="path_of_your_pdf/your_pdf_file.pdf" tabindex="-1"><strong>click here</strong></a>
but it's interesting to find out some other ways as above!
Get max and min value from array in JavaScript
Find largest and smallest number in an array with lodash.
_x000D_
_x000D_
var array = [1, 3, 2];_x000D_
var func = _.over(Math.max, Math.min);_x000D_
var [max, min] = func(...array);_x000D_
// => [3, 1]_x000D_
console.log(max);_x000D_
console.log(min);
_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.js"></script>
_x000D_
_x000D_
_x000D_
Mongodb: failed to connect to server on first connect
if it is cluster MongoDB then you need to add your current IP to the cluster, to add your current IP address you need to complete few steps below-
step 1- go to login page of Mongodb and login with valid credential - https://cloud.mongodb.com/user#/atlas/login
step 2- CLick Network Access from left sidebar under Security Section
Step 3 - Click Add IP Address
Step 4 - Click Add Current IP Address or Allow Connection From Any Where
now try to connect - npm start
![enter image description here](https://i.stack.imgur.com/wsgOZ.png)
and for Local MongoDB use mongo String like
"mongodb+srv://username:pass%[email protected]/test?retryWrites=true&w=majority"
password must be encoded like example string
How to publish a website made by Node.js to Github Pages?
We, the Javascript lovers, don't have to use Ruby (Jekyll or Octopress) to generate static pages in Github pages, we can use Node.js and Harp, for example:
These are the steps. Abstract:
- Create a New Repository
Clone the Repository
git clone https://github.com/your-github-user-name/your-github-user-name.github.io.git
Initialize a Harp app (locally):
harp init _harp
make sure to name the folder with an underscore at the beginning; when you deploy to GitHub Pages, you don’t want your source files to be served.
Compile your Harp app
harp compile _harp ./
Deploy to Gihub
git add -A
git commit -a -m "First Harp + Pages commit"
git push origin master
And this is a cool tutorial with details about nice stuff like layouts, partials, Jade and Less.
Passing arguments forward to another javascript function
try this
function global_func(...args){
for(let i of args){
console.log(i)
}
}
global_func('task_name', 'action', [{x: 'x'},{x: 'x'}], {x: 'x'}, ['x1','x2'], 1, null, undefined, false, true)
//task_name
//action
//(2) [{...},
// {...}]
// {
// x:"x"
// }
//(2) [
// "x1",
// "x2"
// ]
//1
//null
//undefined
//false
//true
//func
Quoting backslashes in Python string literals
You're being mislead by output -- the second approach you're taking actually does what you want, you just aren't believing it. :)
>>> foo = 'baz "\\"'
>>> foo
'baz "\\"'
>>> print(foo)
baz "\"
Incidentally, there's another string form which might be a bit clearer:
>>> print(r'baz "\"')
baz "\"
What's the difference between JavaScript and Java?
Take a look at the Wikipedia link
JavaScript, despite the name, is essentially unrelated to the Java programming language, although both have the common C syntax, and JavaScript copies many Java names and naming conventions. The language was originally named "LiveScript" but was renamed in a co-marketing deal between Netscape and Sun, in exchange for Netscape bundling Sun's Java runtime with their then-dominant browser. The key design principles within JavaScript are inherited from the Self and Scheme programming languages.
How do I find the length (or dimensions, size) of a numpy matrix in python?
shape
is a property of both numpy ndarray's and matrices.
A.shape
will return a tuple (m, n), where m is the number of rows, and n is the number of columns.
In fact, the numpy matrix
object is built on top of the ndarray
object, one of numpy's two fundamental objects (along with a universal function object), so it inherits from ndarray
How to use the IEqualityComparer
If you want a generic solution without boxing:
public class KeyBasedEqualityComparer<T, TKey> : IEqualityComparer<T>
{
private readonly Func<T, TKey> _keyGetter;
public KeyBasedEqualityComparer(Func<T, TKey> keyGetter)
{
_keyGetter = keyGetter;
}
public bool Equals(T x, T y)
{
return EqualityComparer<TKey>.Default.Equals(_keyGetter(x), _keyGetter(y));
}
public int GetHashCode(T obj)
{
TKey key = _keyGetter(obj);
return key == null ? 0 : key.GetHashCode();
}
}
public static class KeyBasedEqualityComparer<T>
{
public static KeyBasedEqualityComparer<T, TKey> Create<TKey>(Func<T, TKey> keyGetter)
{
return new KeyBasedEqualityComparer<T, TKey>(keyGetter);
}
}
usage:
KeyBasedEqualityComparer<Class_reglement>.Create(x => x.Numf)
When use ResponseEntity<T> and @RestController for Spring RESTful applications
According to official documentation: Creating REST Controllers with the @RestController annotation
@RestController is a stereotype annotation that combines @ResponseBody
and @Controller. More than that, it gives more meaning to your
Controller and also may carry additional semantics in future releases
of the framework.
It seems that it's best to use @RestController
for clarity, but you can also combine it with ResponseEntity
for flexibility when needed (According to official tutorial and the code here and my question to confirm that).
For example:
@RestController
public class MyController {
@GetMapping(path = "/test")
@ResponseStatus(HttpStatus.OK)
public User test() {
User user = new User();
user.setName("Name 1");
return user;
}
}
is the same as:
@RestController
public class MyController {
@GetMapping(path = "/test")
public ResponseEntity<User> test() {
User user = new User();
user.setName("Name 1");
HttpHeaders responseHeaders = new HttpHeaders();
// ...
return new ResponseEntity<>(user, responseHeaders, HttpStatus.OK);
}
}
This way, you can define ResponseEntity
only when needed.
Update
You can use this:
return ResponseEntity.ok().headers(responseHeaders).body(user);
Named tuple and default values for optional keyword arguments
Since you are using namedtuple
as a data class, you should be aware that python 3.7 will introduce a @dataclass
decorator for this very purpose -- and of course it has default values.
An example from the docs:
@dataclass
class C:
a: int # 'a' has no default value
b: int = 0 # assign a default value for 'b'
Much cleaner, readable and usable than hacking namedtuple
. It is not hard to predict that usage of namedtuple
s will drop with the adoption of 3.7.
Fragments onResume from back stack
onResume() for the fragment works fine...
public class listBook extends Fragment {
private String listbook_last_subtitle;
...
@Override
public void onCreate(Bundle savedInstanceState) {
String thisFragSubtitle = (String) getActivity().getActionBar().getSubtitle();
listbook_last_subtitle = thisFragSubtitle;
}
...
@Override
public void onResume(){
super.onResume();
getActivity().getActionBar().setSubtitle(listbook_last_subtitle);
}
...
Flatten an irregular list of lists
Here's a simple function that flattens lists of arbitrary depth. No recursion, to avoid stack overflow.
from copy import deepcopy
def flatten_list(nested_list):
"""Flatten an arbitrarily nested list, without recursion (to avoid
stack overflows). Returns a new list, the original list is unchanged.
>> list(flatten_list([1, 2, 3, [4], [], [[[[[[[[[5]]]]]]]]]]))
[1, 2, 3, 4, 5]
>> list(flatten_list([[1, 2], 3]))
[1, 2, 3]
"""
nested_list = deepcopy(nested_list)
while nested_list:
sublist = nested_list.pop(0)
if isinstance(sublist, list):
nested_list = sublist + nested_list
else:
yield sublist
How do I get the domain originating the request in express.js?
You have to retrieve it from the HOST
header.
var host = req.get('host');
It is optional with HTTP 1.0, but required by 1.1. And, the app can always impose a requirement of its own.
If this is for supporting cross-origin requests, you would instead use the Origin
header.
var origin = req.get('origin');
Note that some cross-origin requests require validation through a "preflight" request:
req.options('/route', function (req, res) {
var origin = req.get('origin');
// ...
});
If you're looking for the client's IP, you can retrieve that with:
var userIP = req.socket.remoteAddress;
Note that, if your server is behind a proxy, this will likely give you the proxy's IP. Whether you can get the user's IP depends on what info the proxy passes along. But, it'll typically be in the headers as well.
When to use MongoDB or other document oriented database systems?
In NoSQL: If Only It Was That Easy, the author writes about MongoDB:
MongoDB is not a key/value store, it’s quite a bit more. It’s definitely not a RDBMS either. I haven’t used MongoDB in production, but I have used it a little building a test app and it is a very cool piece of kit. It seems to be very performant and either has, or will have soon, fault tolerance and auto-sharding (aka it will scale). I think Mongo might be the closest thing to a RDBMS replacement that I’ve seen so far. It won’t work for all data sets and access patterns, but it’s built for your typical CRUD stuff. Storing what is essentially a huge hash, and being able to select on any of those keys, is what most people use a relational database for. If your DB is 3NF and you don’t do any joins (you’re just selecting a bunch of tables and putting all the objects together, AKA what most people do in a web app), MongoDB would probably kick ass for you.
Then, in the conclusion:
The real thing to point out is that if you are being held back from making something super awesome because you can’t choose a database, you are doing it wrong. If you know mysql, just use it. Optimize when you actually need to. Use it like a k/v store, use it like a rdbms, but for god sake, build your killer app! None of this will matter to most apps. Facebook still uses MySQL, a lot. Wikipedia uses MySQL, a lot. FriendFeed uses MySQL, a lot. NoSQL is a great tool, but it’s certainly not going to be your competitive edge, it’s not going to make your app hot, and most of all, your users won’t care about any of this.
What am I going to build my next app on? Probably Postgres. Will I use NoSQL? Maybe. I might also use Hadoop and Hive. I might keep everything in flat files. Maybe I’ll start hacking on Maglev. I’ll use whatever is best for the job. If I need reporting, I won’t be using any NoSQL. If I need caching, I’ll probably use Tokyo Tyrant. If I need ACIDity, I won’t use NoSQL. If I need a ton of counters, I’ll use Redis. If I need transactions, I’ll use Postgres. If I have a ton of a single type of documents, I’ll probably use Mongo. If I need to write 1 billion objects a day, I’d probably use Voldemort. If I need full text search, I’d probably use Solr. If I need full text search of volatile data, I’d probably use Sphinx.
I like this article, I find it very informative, it gives a good overview of the NoSQL landscape and hype. But, and that's the most important part, it really helps to ask yourself the right questions when it comes to choose between RDBMS and NoSQL. Worth the read IMHO.
Alternate link to article
jQuery: get parent tr for selected radio button
Try this.
You don't need to prefix attribute name by @
in jQuery selector. Use closest()
method to get the closest parent element matching the selector.
$("#MwDataList input[name=selectRadioGroup]:checked").closest('tr');
You can simplify your method like this
function getSelectedRowGuid() {
return GetRowGuid(
$("#MwDataList > input:radio[@name=selectRadioGroup]:checked :parent tr"));
}
closest()
- Gets the first element that matches the selector, beginning at the current element and progressing up through the DOM tree.
As a side note, the ids of the elements should be unique on the page so try to avoid having same ids for radio buttons which I can see in your markup. If you are not going to use the ids then just remove it from the markup.
What is the optimal way to compare dates in Microsoft SQL server?
Here is an example:
I've an Order table with a DateTime field called OrderDate. I want to retrieve all orders where the order date is equals to 01/01/2006. there are next ways to do it:
1) WHERE DateDiff(dd, OrderDate, '01/01/2006') = 0
2) WHERE Convert(varchar(20), OrderDate, 101) = '01/01/2006'
3) WHERE Year(OrderDate) = 2006 AND Month(OrderDate) = 1 and Day(OrderDate)=1
4) WHERE OrderDate LIKE '01/01/2006%'
5) WHERE OrderDate >= '01/01/2006' AND OrderDate < '01/02/2006'
Is found here
The property 'value' does not exist on value of type 'HTMLElement'
The problem is here:
document.getElementById(elementId).value
You know that HTMLElement
returned from getElementById()
is actually an instance of HTMLInputElement
inheriting from it because you are passing an ID of input element. Similarly in statically typed Java this won't compile:
public Object foo() {
return 42;
}
foo().signum();
signum()
is a method of Integer
, but the compiler only knows the static type of foo()
, which is Object
. And Object
doesn't have a signum()
method.
But the compiler can't know that, it can only base on static types, not dynamic behaviour of your code. And as far as the compiler knows, the type of document.getElementById(elementId)
expression does not have value
property. Only input elements have value.
For a reference check HTMLElement
and HTMLInputElement
in MDN. I guess Typescript is more or less consistent with these.
Mysql: Setup the format of DATETIME to 'DD-MM-YYYY HH:MM:SS' when creating a table
I'm pretty certain that you can't change the datetime format in mysql. The phpmyadmin setting is probably applying a custom format as it reads the datetime (using DATE_FORMAT or something from php). It shouldn't matter what format the database uses, format in the application to display it as you wish.
Date formatting is a pretty common task. I typically like to abstract it out into internationalization code or, if you don't need to deal with i18n, into a common date utility library. It helps keep things consistent and makes it easier to change later (or add i18n support).
MongoDB: How to find the exact version of installed MongoDB
To check mongodb version use the mongod command with --version
option.
To check MongoDB Server version, Open the command line via your terminal program and execute the following command:
Path :
C:\Program Files\MongoDB\Server\3.2\bin
Open Cmd and
execute the following command:
mongod --version
To Check MongoDB Shell version, Type:
mongo --version
Returning http 200 OK with error within response body
No, this is very incorrect.
HTTP is an application protocol. 200 implies that the response contains a payload that represents the status of the requested resource. An error message usually is not a representation of that resource.
If something goes wrong while processing GET, the right status code is 4xx ("you messed up") or 5xx ("I messed up").
Why calling react setState method doesn't mutate the state immediately?
As mentioned in the React documentation, there is no guarantee of setState
being fired synchronously, so your console.log
may return the state prior to it updating.
Michael Parker mentions passing a callback within the setState
. Another way to handle the logic after state change is via the componentDidUpdate
lifecycle method, which is the method recommended in React docs.
Generally we recommend using componentDidUpdate() for such logic instead.
This is particularly useful when there may be successive setState
s fired, and you would like to fire the same function after every state change. Rather than adding a callback to each setState
, you could place the function inside of the componentDidUpdate
, with specific logic inside if necessary.
// example
componentDidUpdate(prevProps, prevState) {
if (this.state.value > prevState.value) {
this.foo();
}
}
How to execute a JavaScript function when I have its name as a string
Two things:
avoid eval, it's terribly dangerous and slow
secondly it doesn't matter where your function exists, "global" -ness is irrelevant. x.y.foo()
can be enabled through x.y['foo']()
or x['y']['foo']()
or even window['x']['y']['foo']()
. You can chain indefinitely like this.
jQuery Force set src attribute for iframe
You cannot set FIX iframe's src or prevent javascript/form submit to change its location. However you can put script to onload of the page and change action of each dynamic link.
How to create an AVD for Android 4.0
This answer is for creating AVD in Android Studio.
- First click on AVD button on your Android Studio top bar.
![image 1](https://i.stack.imgur.com/r2OkJ.png)
- In this window click on Create Virtual Device
![image 2](https://i.stack.imgur.com/g7tlv.png)
- Now you will choose hardware profile for AVD and click Next.
![image 3](https://i.stack.imgur.com/zgWDg.png)
- Choose Android Api Version you want in your AVD. Download if no api exist. Click next.
![image 4](https://i.stack.imgur.com/d4PV7.png)
- This is now window for customizing some AVD feature like camera, network, memory and ram size etc. Just keep default and click Finish.
![image 5](https://i.stack.imgur.com/1oO4t.png)
- You AVD is ready, now click on AVD button in Android Studio (same like 1st step). Then you will able to see created AVD in list. Click on Play button on your AVD.
![image 6](https://i.stack.imgur.com/PoHOE.png)
- Your AVD will start soon.
![image 7](https://i.stack.imgur.com/Ss29g.png)
How to Execute a Python File in Notepad ++?
Here is what's worked for me:
Open notepad++ and press F5. You'll get a little popup box:
![Pop up box for entering the program to run](https://i.stack.imgur.com/CUrbF.jpg)
Type: C:\Python27\python.exe -i "$(FULL_CURRENT_PATH)" for Python 2.7.
and then Save As..., and pick your own key combo to start it each time you want to run something
How to round up integer division and have int result in Java?
To round up an integer division you can use
import static java.lang.Math.abs;
public static long roundUp(long num, long divisor) {
int sign = (num > 0 ? 1 : -1) * (divisor > 0 ? 1 : -1);
return sign * (abs(num) + abs(divisor) - 1) / abs(divisor);
}
or if both numbers are positive
public static long roundUp(long num, long divisor) {
return (num + divisor - 1) / divisor;
}
What does "res.render" do, and what does the html file look like?
What does res.render do and what does the html file look like?
res.render()
function compiles your template (please don't use ejs), inserts locals there, and creates html output out of those two things.
Answering Edit 2 part.
// here you set that all templates are located in `/views` directory
app.set('views', __dirname + '/views');
// here you set that you're using `ejs` template engine, and the
// default extension is `ejs`
app.set('view engine', 'ejs');
// here you render `orders` template
response.render("orders", {orders: orders_json});
So, the template path is views/
(first part) + orders
(second part) + .ejs
(third part) === views/orders.ejs
Anyway, express.js documentation is good for what it does. It is API reference, not a "how to use node.js" book.
Password Protect a SQLite DB. Is it possible?
Why do you need to encrypt the database? The user could easily disassemble your program and figure out the key. If you're encrypting it for network transfer, then consider using PGP instead of squeezing an encryption layer into a database layer.
Multiple INNER JOIN SQL ACCESS
Thanks HansUp for your answer, it is very helpful and it works!
I found three patterns working in Access, yours is the best, because it works in all cases.
INNER JOIN, your variant. I will call it "closed set pattern".
It is possible to join more than two tables to the same table with good performance only with this pattern.
SELECT C_Name, cr.P_FirstName+" "+cr.P_SurName AS ClassRepresentativ, cr2.P_FirstName+" "+cr2.P_SurName AS ClassRepresentativ2nd
FROM
((class
INNER JOIN person AS cr
ON class.C_P_ClassRep=cr.P_Nr
)
INNER JOIN person AS cr2
ON class.C_P_ClassRep2nd=cr2.P_Nr
)
;
INNER JOIN "chained-set pattern"
SELECT C_Name, cr.P_FirstName+" "+cr.P_SurName AS ClassRepresentativ, cr2.P_FirstName+" "+cr2.P_SurName AS ClassRepresentativ2nd
FROM person AS cr
INNER JOIN ( class
INNER JOIN ( person AS cr2
) ON class.C_P_ClassRep2nd=cr2.P_Nr
) ON class.C_P_ClassRep=cr.P_Nr
;
CROSS JOIN with WHERE
SELECT C_Name, cr.P_FirstName+" "+cr.P_SurName AS ClassRepresentativ, cr2.P_FirstName+" "+cr2.P_SurName AS ClassRepresentativ2nd
FROM class, person AS cr, person AS cr2
WHERE class.C_P_ClassRep=cr.P_Nr AND class.C_P_ClassRep2nd=cr2.P_Nr
;
Java AES and using my own Key
This wll work.
public class CryptoUtils {
private final String TRANSFORMATION = "AES";
private final String encodekey = "1234543444555666";
public String encrypt(String inputFile)
throws CryptoException {
return doEncrypt(encodekey, inputFile);
}
public String decrypt(String input)
throws CryptoException {
// return doCrypto(Cipher.DECRYPT_MODE, key, inputFile);
return doDecrypt(encodekey,input);
}
private String doEncrypt(String encodekey, String inputStr) throws CryptoException {
try {
Cipher cipher = Cipher.getInstance(TRANSFORMATION);
byte[] key = encodekey.getBytes("UTF-8");
MessageDigest sha = MessageDigest.getInstance("SHA-1");
key = sha.digest(key);
key = Arrays.copyOf(key, 16); // use only first 128 bit
SecretKeySpec secretKeySpec = new SecretKeySpec(key, "AES");
cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec);
byte[] inputBytes = inputStr.getBytes();
byte[] outputBytes = cipher.doFinal(inputBytes);
return Base64Utils.encodeToString(outputBytes);
} catch (NoSuchPaddingException | NoSuchAlgorithmException
| InvalidKeyException | BadPaddingException
| IllegalBlockSizeException | IOException ex) {
throw new CryptoException("Error encrypting/decrypting file", ex);
}
}
public String doDecrypt(String encodekey,String encrptedStr) {
try {
Cipher dcipher = Cipher.getInstance(TRANSFORMATION);
dcipher = Cipher.getInstance("AES");
byte[] key = encodekey.getBytes("UTF-8");
MessageDigest sha = MessageDigest.getInstance("SHA-1");
key = sha.digest(key);
key = Arrays.copyOf(key, 16); // use only first 128 bit
SecretKeySpec secretKeySpec = new SecretKeySpec(key, "AES");
dcipher.init(Cipher.DECRYPT_MODE, secretKeySpec);
// decode with base64 to get bytes
byte[] dec = Base64Utils.decode(encrptedStr.getBytes());
byte[] utf8 = dcipher.doFinal(dec);
// create new string based on the specified charset
return new String(utf8, "UTF8");
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}
What values can I pass to the event attribute of the f:ajax tag?
I just input some value that I knew was invalid and here is the output:
'whatToInput' is not a supported event for HtmlPanelGrid.
Please specify one of these supported event names: click, dblclick,
keydown, keypress, keyup, mousedown, mousemove, mouseout, mouseover,
mouseup.
So values you can pass to event are
- click
- dblclick
- keydown
- mousedown
- mousemove
- mouseover
- mouseup
Could you explain STA and MTA?
As my understanding, the 'Apartment' is used to protect the COM objects from multi-threading issues.
If a COM object is not thread-safe, it should declare it as a STA object. Then only the thread who creates it can access it. The creation thread should declare itself as a STA thread. Under the hood, the thread stores the STA information in its TLS(Thread Local Storage). We call this behavior as that the thread enters a STA apartment. When other threads want to access this COM object, it should marshal the access to the creation thread. Basically, the creation thread uses messages mechanism to process the in-bound calls.
If a COM object is thread-safe, it should declare it as a MTA object. The MTA object can be accessed by multi-threads.
How to insert a text at the beginning of a file?
PROBLEM: tag a file, at the top of the file, with the base name of the parent directory.
I.e., for
/mnt/Vancouver/Programming/file1
tag the top of file1
with Programming
.
SOLUTION 1 -- non-empty files:
bn=${PWD##*/} ## bn: basename
sed -i '1s/^/'"$bn"'\n/' <file>
1s
places the text at line 1 of the file.
SOLUTION 2 -- empty or non-empty files:
The sed
command, above, fails on empty files. Here is a solution, based on https://superuser.com/questions/246837/how-do-i-add-text-to-the-beginning-of-a-file-in-bash/246841#246841
printf "${PWD##*/}\n" | cat - <file> > temp && mv -f temp <file>
Note that the -
in the cat command is required (reads standard input: see man cat
for more information). Here, I believe, it's needed to take the output of the printf statement (to STDIN), and cat that and the file to temp ... See also the explanation at the bottom of http://www.linfo.org/cat.html.
I also added -f
to the mv
command, to avoid being asked for confirmations when overwriting files.
To recurse over a directory:
for file in *; do printf "${PWD##*/}\n" | cat - $file > temp && mv -f temp $file; done
Note also that this will break over paths with spaces; there are solutions, elsewhere (e.g. file globbing, or find . -type f ...
-type solutions) for those.
ADDENDUM: Re: my last comment, this script will allow you to recurse over directories with spaces in the paths:
#!/bin/bash
## https://stackoverflow.com/questions/4638874/how-to-loop-through-a-directory-recursively-to-delete-files-with-certain-extensi
## To allow spaces in filenames,
## at the top of the script include: IFS=$'\n'; set -f
## at the end of the script include: unset IFS; set +f
IFS=$'\n'; set -f
# ----------------------------------------------------------------------------
# SET PATHS:
IN="/mnt/Vancouver/Programming/data/claws-test/corpus test/"
# https://superuser.com/questions/716001/how-can-i-get-files-with-numeric-names-using-ls-command
# FILES=$(find $IN -type f -regex ".*/[0-9]*") ## recursive; numeric filenames only
FILES=$(find $IN -type f -regex ".*/[0-9 ]*") ## recursive; numeric filenames only (may include spaces)
# echo '$FILES:' ## single-quoted, (literally) prints: $FILES:
# echo "$FILES" ## double-quoted, prints path/, filename (one per line)
# ----------------------------------------------------------------------------
# MAIN LOOP:
for f in $FILES
do
# Tag top of file with basename of current dir:
printf "[top] Tag: ${PWD##*/}\n\n" | cat - $f > temp && mv -f temp $f
# Tag bottom of file with basename of current dir:
printf "\n[bottom] Tag: ${PWD##*/}\n" >> $f
done
unset IFS; set +f
How I can get web page's content and save it into the string variable
I recommend not using WebClient.DownloadString
. This is because (at least in .NET 3.5) DownloadString is not smart enough to use/remove the BOM, should it be present. This can result in the BOM (
) incorrectly appearing as part of the string when UTF-8 data is returned (at least without a charset) - ick!
Instead, this slight variation will work correctly with BOMs:
string ReadTextFromUrl(string url) {
// WebClient is still convenient
// Assume UTF8, but detect BOM - could also honor response charset I suppose
using (var client = new WebClient())
using (var stream = client.OpenRead(url))
using (var textReader = new StreamReader(stream, Encoding.UTF8, true)) {
return textReader.ReadToEnd();
}
}
Detect all changes to a <input type="text"> (immediately) using JQuery
I have created a sample. May it will work for you.
var typingTimer;
var doneTypingInterval = 10;
var finaldoneTypingInterval = 500;
var oldData = $("p.content").html();
$('#tyingBox').keydown(function () {
clearTimeout(typingTimer);
if ($('#tyingBox').val) {
typingTimer = setTimeout(function () {
$("p.content").html('Typing...');
}, doneTypingInterval);
}
});
$('#tyingBox').keyup(function () {
clearTimeout(typingTimer);
typingTimer = setTimeout(function () {
$("p.content").html(oldData);
}, finaldoneTypingInterval);
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<textarea id="tyingBox" tabindex="1" placeholder="Enter Message"></textarea>
<p class="content">Text will be replace here and after Stop typing it will get back</p>
http://jsfiddle.net/utbh575s/
How can I retrieve a table from stored procedure to a datatable?
Set the CommandText
as well, and call Fill
on the SqlAdapter
to retrieve the results in a DataSet
:
var con = new SqlConnection();
con.ConnectionString = "connection string";
var com = new SqlCommand();
com.Connection = con;
com.CommandType = CommandType.StoredProcedure;
com.CommandText = "sp_returnTable";
var adapt = new SqlDataAdapter();
adapt.SelectCommand = com;
var dataset = new DataSet();
adapt.Fill(dataset);
(Example is using parameterless constructors for clarity; can be shortened by using other constructors.)
Switch on ranges of integers in JavaScript
This does not require a switch statement. It is clearer, more concise, faster, and optimises better, to use if else statements...
var d = this.dealer;
if (1 <= d && d <= 11) { // making sure in range 1..11
if (d <= 4) {
alert("1 to 4");
} else if (d <= 8) {
alert("5 to 8");
} else {
alert("9 to 11");
}
} else {
alert("not in range");
}
Speed test
I was curious about the overhead of using a switch instead of the simpler if...else..., so I put together a jsFiddle to examine it...
http://jsfiddle.net/17x9w1eL/
Chrome: switch was around 70% slower than if else
Firefox: switch was around 5% slower than if else
IE: switch was around 5% slower than if else
Safari: switch was around 95% slower than if else
Notes:
Assigning to the local variable is optional, especially if your code is going to be automatically optimised later.
For numeric ranges, I like to use this kind of construction...
if (1 <= d && d <= 11) {...}
... because to me it reads closer to the way you would express a range in maths (1 <= d <= 11), and when I'm reading the code, I can read that as "if d is between 1 and 11".
Clearer
A few people don't think this is clearer. I'd say it is not less clear as the structure is close to identical to the switch option. The main reason it is clearer is that every part of it is readable and makes simple intuitive sense.
My concern, with "switch (true)", is that it can appear to be a meaningless line of code. Many coders, reading that will not know what to make of it.
For my own code, I'm more willing to use obscure structures from time to time, but if anyone else will look at it, I try to use clearer constructs. I think it is better to use the constructs for what they are intended.
Optimisation
In a modern environment, code is often going to be minified for production, so you can write clear concise code, with readable variable names and helpful comments. There's no clear reason to use switch in this way.
I also tried putting both constructs through a minifier. The if/else structure compresses well, becoming a single short expression using nested ternary operators. The switch statement when minified remains a switch, complete with "switch", "case" and "break" tokens, and as a result is considerably longer in code.
How switch(true) works
I think "switch(true) is obscure, but it seems some people just want to use it, so here's an explanation of why it works...
A switch/case statement works by matching the part in the switch with each case, and then executing the code on the first match. In most use cases, we have a variable or non-constant expression in the switch, and then match it.
With "switch(true), we will find the first expression in the case statements that is true. If you read "switch (true)" as "find the first expression that is true", the code feels more readable.
What is ADT? (Abstract Data Type)
ADT is a data type in which collection of data and operation works on that data . It focuses on more the concept than implementation..
It's up to you which language you use to make it visible on the earth
Example:
Stack is an ADT while the Array is not
Stack is ADT because we can implement it by many languages,
Python c c++ java and many more , while Array is built in data type
How do I format date and time on ssrs report?
If you click on the empty spot on the report away from any table and then look in properties, one of the Misc fields is called Language which allows you to pick which Language you would like to set, which after doing so can play around with this
=FormatDateTime(now,x)
Which x
can be 1, 2, 3, 4, 5
How to comment lines in rails html.erb files?
This is CLEANEST, SIMPLEST ANSWER for CONTIGUOUS NON-PRINTING Ruby Code:
The below also happens to answer the Original Poster's question without, the "ugly" conditional code that some commenters have mentioned.
CONTIGUOUS NON-PRINTING Ruby Code
This will work in any mixed language Rails View file, e.g, *.html.erb, *.js.erb, *.rhtml
, etc.
This should also work with STD OUT/printing code, e.g. <%#= f.label :title %>
DETAILS:
Rather than use rails brackets on each line and commenting in front of each starting bracket as we usually do like this:
<%# if flash[:myErrors] %>
<%# if flash[:myErrors].any? %>
<%# if @post.id.nil? %>
<%# if @myPost!=-1 %>
<%# @post = @myPost %>
<%# else %>
<%# @post = Post.new %>
<%# end %>
<%# end %>
<%# end %>
<%# end %>
YOU CAN INSTEAD add only one comment (hashmark/poundsign) to the first open Rails bracket if you write your code as one large block... LIKE THIS:
<%#
if flash[:myErrors] then
if flash[:myErrors].any? then
if @post.id.nil? then
if @myPost!=-1 then
@post = @myPost
else
@post = Post.new
end
end
end
end
%>
Background color on input type=button :hover state sticks in IE
There might be a fix to <input type="button">
- but if there is, I don't know it.
Otherwise, a good option seems to be to replace it with a carefully styled a
element.
Example: http://jsfiddle.net/Uka5v/
.button {
background-color: #E3E1B8;
padding: 2px 4px;
font: 13px sans-serif;
text-decoration: none;
border: 1px solid #000;
border-color: #aaa #444 #444 #aaa;
color: #000
}
Upsides include that the a
element will style consistently between different (older) versions of Internet Explorer without any extra work, and I think my link looks nicer than that button :)
Resize a picture to fit a JLabel
Or u can do it this way. The function u put the below 6 lines will throw an IOException. And will take your JLabel as a parameter.
BufferedImage bi=new BufferedImage(label.width(),label.height(),BufferedImage.TYPE_INT_RGB);
Graphics2D g=bi.createGraphics();
Image img=ImageIO.read(new File("path of your image"));
g.drawImage(img, 0, 0, label.width(), label.height(), null);
g.dispose();
return bi;
using CASE in the WHERE clause
You don't have to use CASE...WHEN, you could use an OR condition, like this:
WHERE
pw='correct'
AND (id>=800 OR success=1)
AND YEAR(timestamp)=2011
this means that if id<800, success has to be 1 for the condition to be evaluated as true. Otherwise, it will be true anyway.
It is less common, however you could still use CASE WHEN, like this:
WHERE
pw='correct'
AND CASE WHEN id<800 THEN success=1 ELSE TRUE END
AND YEAR(timestamp)=2011
this means: return success=1
(which can be TRUE or FALSE) in case id<800, or always return TRUE otherwise.
Codeigniter - multiple database connections
Use this.
$dsn1 = 'mysql://user:password@localhost/db1';
$this->db1 = $this->load->database($dsn1, true);
$dsn2 = 'mysql://user:password@localhost/db2';
$this->db2= $this->load->database($dsn2, true);
$dsn3 = 'mysql://user:password@localhost/db3';
$this->db3= $this->load->database($dsn3, true);
Usage
$this->db1 ->insert('tablename', $insert_array);
$this->db2->insert('tablename', $insert_array);
$this->db3->insert('tablename', $insert_array);
Symfony2 and date_default_timezone_get() - It is not safe to rely on the system's timezone settings
Found a similar way to fix this issue (at least it did for me).
First check where the CLI php.ini
is located:
php -i | grep "php.ini"
In my case I ended up with : Configuration File (php.ini) Path => /etc
Then cd ..
all the way back and cd
into /etc
, do ls
in my case php.ini didn't show up, only a php.ini.default
Now, copy the php.ini.default file named as php.ini:
sudo cp php.ini.default php.ini
In order to edit, change the permissions of the file:
sudo chmod ug+w php.ini
sudo chgrp staff php.ini
Open directory and edit the php.ini file:
open .
Tip: If you are not able to edit the php.ini due to some permissions issue then copy 'php.ini.default' and paste it on your desktop and rename it to 'php.ini' then open it and edit it following step 7. Then move (copy+paste) it in /etc folder. Issue will be resolved.
Search for [Date] and make sure the following line is in the correct format:
date.timezone = "Europe/Amsterdam"
I hope this could help you out.
How to use workbook.saveas with automatic Overwrite
I recommend that before executing SaveAs, delete the file it exists.
If Dir("f:ull\path\with\filename.xls") <> "" Then
Kill "f:ull\path\with\filename.xls"
End If
It's easier than setting DisplayAlerts off and on, plus if DisplayAlerts remains off due to code crash, it can cause problems if you work with Excel in the same session.
How to get Current Directory?
Please don't forget to initialize your buffers to something before utilizing them. And just as important, give your string buffers space for the ending null
TCHAR path[MAX_PATH+1] = L"";
DWORD len = GetCurrentDirectory(MAX_PATH, path);
Reference
MVC Razor Hidden input and passing values
If you are using Razor, you cannot access the field directly, but you can manage its value.
The idea is that the first Microsoft approach drive the developers away from Web Development and make it easy for Desktop programmers (for example) to make web applications.
Meanwhile, the web developers, did not understand this tricky strange way of ASP.NET.
Actually this hidden input is rendered on client-side, and the ASP has no access to it (it never had). However, in time you will see its a piratical way and you may rely on it, when you get use with it. The web development differs from the Desktop or Mobile.
The model is your logical unit, and the hidden field (and the whole view page) is just a representative view of the data. So you can dedicate your work on the application or domain logic and the view simply just serves it to the consumer - which means you need no detailed access and "brainstorming" functionality in the view.
The controller actually does work you need for manage the hidden or general setup. The model serves specific logical unit properties and functionality and the view just renders it to the end user, simply said. Read more about MVC.
Model
public class MyClassModel
{
public int Id { get; set; }
public string Name { get; set; }
public string MyPropertyForHidden { get; set; }
}
This is the controller aciton
public ActionResult MyPageView()
{
MyClassModel model = new MyClassModel(); // Single entity, strongly-typed
// IList model = new List<MyClassModel>(); // or List, strongly-typed
// ViewBag.MyHiddenInputValue = "Something to pass"; // ...or using ViewBag
return View(model);
}
The view is below
//This will make a Model property of the View to be of MyClassModel
@model MyNamespace.Models.MyClassModel // strongly-typed view
// @model IList<MyNamespace.Models.MyClassModel> // list, strongly-typed view
// ... Some Other Code ...
@using(Html.BeginForm()) // Creates <form>
{
// Renders hidden field for your model property (strongly-typed)
// The field rendered to server your model property (Address, Phone, etc.)
Html.HiddenFor(model => Model.MyPropertyForHidden);
// For list you may use foreach on Model
// foreach(var item in Model) or foreach(MyClassModel item in Model)
}
// ... Some Other Code ...
The view with ViewBag:
// ... Some Other Code ...
@using(Html.BeginForm()) // Creates <form>
{
Html.Hidden(
"HiddenName",
ViewBag.MyHiddenInputValue,
new { @class = "hiddencss", maxlength = 255 /*, etc... */ }
);
}
// ... Some Other Code ...
We are using Html Helper to render the Hidden field or we could write it by hand - <input name=".." id=".." value="ViewBag.MyHiddenInputValue">
also.
The ViewBag is some sort of data carrier to the view. It does not restrict you with model - you can place whatever you like.
Check folder size in Bash
To just get the size of the directory, nothing more:
du --max-depth=0 ./directory
output looks like
5234232 ./directory
Convert a string representation of a hex dump to a byte array using Java?
Based on the op voted solution, the following should be a bit more efficient:
public static byte [] hexStringToByteArray (final String s) {
if (s == null || (s.length () % 2) == 1)
throw new IllegalArgumentException ();
final char [] chars = s.toCharArray ();
final int len = chars.length;
final byte [] data = new byte [len / 2];
for (int i = 0; i < len; i += 2) {
data[i / 2] = (byte) ((Character.digit (chars[i], 16) << 4) + Character.digit (chars[i + 1], 16));
}
return data;
}
Because: the initial conversion to a char array spares the length checks in charAt
How do you delete all text above a certain line
Providing you know these vim commands:
1G -> go to first line in file
G -> go to last line in file
then, the following make more sense, are more unitary and easier to remember IMHO:
d1G -> delete starting from the line you are on, to the first line of file
dG -> delete starting from the line you are on, to the last line of file
Cheers.
Error: EACCES: permission denied, access '/usr/local/lib/node_modules'
If you are facing this issue on you Mac. Follow these steps
First checking who is owner of this file by using below command
ls -la /usr/local/lib/node_modules
you will find some file like below one of them is below
drwxr-xr-x 3 root wheel 768 May 29 02:21 node_modules
have you notice that above file is own by root, for make changes inside for you need to change owner ship of path.
you can use check who is current user by this command
id -un (in my case user is yamsol)
and then you can change by calling this command (just replace your user name with ownerName)
sudo chown -R ownerName: /usr/local/lib/node_modules
in my case as you know user is "yamsol" i will call this command in this way
sudo chown -R yamsol: /usr/local/lib/node_modules
thats it.
How can I copy a file from a remote server to using Putty in Windows?
It worked using PSCP.
Instructions:
- Download PSCP.EXE from Putty download page
- Open command prompt and type
set PATH=<path to the pscp.exe file>
- In command prompt point to the location of the pscp.exe using cd command
- Type
pscp
use the following command to copy file form remote server to the local system
pscp [options] [user@]host:source target
So to copy the file /etc/hosts
from the server example.com
as user fred
to the file
c:\temp\example-hosts.txt
, you would type:
pscp [email protected]:/etc/hosts c:\temp\example-hosts.txt
Conditional WHERE clause in SQL Server
Often when you use conditional WHERE clauses you end upp with a vastly inefficient query, which is noticeable for large datasets where indexes are used. A great way to optimize the query for different values of your parameter is to make a different execution plan for each value of the parameter. You can achieve this using OPTION (RECOMPILE)
.
In this example it would probably not make much difference, but say the condition should only be used in one of two cases, then you could notice a big impact.
In this example:
WHERE
DateDropped = 0
AND (
(ISNULL(@JobsOnHold, 0) = 1 AND DateAppr >= 0)
OR
(ISNULL(@JobsOnHold, 0) <> 1 AND DateAppr <> 0)
)
OPTION (RECOMPILE)
Source Parameter Sniffing, Embedding, and the RECOMPILE Options
Difference in boto3 between resource, client, and session?
Here's some more detailed information on what Client, Resource, and Session are all about.
Client:
- low-level AWS service access
- generated from AWS service description
- exposes botocore client to the developer
- typically maps 1:1 with the AWS service API
- all AWS service operations are supported by clients
- snake-cased method names (e.g. ListBuckets API => list_buckets method)
Here's an example of client-level access to an S3 bucket's objects (at most 1000**):
import boto3
client = boto3.client('s3')
response = client.list_objects_v2(Bucket='mybucket')
for content in response['Contents']:
obj_dict = client.get_object(Bucket='mybucket', Key=content['Key'])
print(content['Key'], obj_dict['LastModified'])
** you would have to use a paginator, or implement your own loop, calling list_objects() repeatedly with a continuation marker if there were more than 1000.
Resource:
- higher-level, object-oriented API
- generated from resource description
- uses identifiers and attributes
- has actions (operations on resources)
- exposes subresources and collections of AWS resources
- does not provide 100% API coverage of AWS services
Here's the equivalent example using resource-level access to an S3 bucket's objects (all):
import boto3
s3 = boto3.resource('s3')
bucket = s3.Bucket('mybucket')
for obj in bucket.objects.all():
print(obj.key, obj.last_modified)
Note that in this case you do not have to make a second API call to get the objects; they're available to you as a collection on the bucket. These collections of subresources are lazily-loaded.
You can see that the Resource
version of the code is much simpler, more compact, and has more capability (it does pagination for you). The Client
version of the code would actually be more complicated than shown above if you wanted to include pagination.
Session:
- stores configuration information (primarily credentials and selected region)
- allows you to create service clients and resources
- boto3 creates a default session for you when needed
A useful resource to learn more about these boto3 concepts is the introductory re:Invent video.
Hide div if screen is smaller than a certain width
The problem with your code seems to be the elseif-statement which should be else if
(Notice the space).
I rewrote and simplyfied the code to this:
$(document).ready(function () {
if (screen.width < 1024) {
$(".yourClass").hide();
}
else {
$(".yourClass").show();
}
});
Windows 7, 64 bit, DLL problems
This contribution does not really answer the initial question, but taking into account the hit-rate of this thread I assume that there are quite a few people dealing with the problem that API-MS-WIN-CORE- libraries cannot be found.
I was able to solve a problem where my application refused to start with the error message that API-MS-WIN-CORE-WINRT-STRING-L1-1-0.DLL is not found by simply updating Visual Studio.
I don't think that my build environment (Windows 7 Pro SP1, Visual Studio Ultimate 2012) was messed up completely, it worked fine for most of my projects. But under some very specific circumstances I got the error message (see below).
After updating Visual Studio 11 from the initial CD-Version (I forgot to look up the version number) to version 11.0.61030.00 Update 4 also the broken project was running again.
![Error message at application startup](https://i.stack.imgur.com/UOf2o.png)
How can I configure Logback to log different levels for a logger to different destinations?
I use logback.groovy to configure my logback but you can do it with xml config as well:
import static ch.qos.logback.classic.Level.*
import static ch.qos.logback.core.spi.FilterReply.DENY
import static ch.qos.logback.core.spi.FilterReply.NEUTRAL
import ch.qos.logback.classic.boolex.GEventEvaluator
import ch.qos.logback.classic.encoder.PatternLayoutEncoder
import ch.qos.logback.core.ConsoleAppender
import ch.qos.logback.core.filter.EvaluatorFilter
def patternExpression = "%date{ISO8601} [%5level] %msg%n"
appender("STDERR", ConsoleAppender) {
filter(EvaluatorFilter) {
evaluator(GEventEvaluator) {
expression = 'e.level.toInt() >= WARN.toInt()'
}
onMatch = NEUTRAL
onMismatch = DENY
}
encoder(PatternLayoutEncoder) {
pattern = patternExpression
}
target = "System.err"
}
appender("STDOUT", ConsoleAppender) {
filter(EvaluatorFilter) {
evaluator(GEventEvaluator) {
expression = 'e.level.toInt() < WARN.toInt()'
}
onMismatch = DENY
onMatch = NEUTRAL
}
encoder(PatternLayoutEncoder) {
pattern = patternExpression
}
target = "System.out"
}
logger("org.hibernate.type", WARN)
logger("org.hibernate", WARN)
logger("org.springframework", WARN)
root(INFO,["STDERR","STDOUT"])
I think to use GEventEvaluator is simplier because there is no need to create filter classes.
I apologize for my English!
Django Reverse with arguments '()' and keyword arguments '{}' not found
This problems gave me great headache when i tried to use reverse for generating activation link and send it via email of course. So i think from tests.py it will be same.
The correct way to do this is following:
from django.test import Client
from django.core.urlresolvers import reverse
#app name - name of the app where the url is defined
client= Client()
response = client.get(reverse('app_name:edit_project', project_id=4))
ld: framework not found Pods
This issue was driving me crazy as it suddenly happened without doing any changes to the project. I've tried all suggested solutions in this thread (and other related) and none of them solved the problem.
The only thing that differed from my other projects (which compiled fine), was that this project name was containing an accent (a french accent, "é"). I've renamed the project and all related files, and it finally worked !
Maybe this is related to updating to Xcode 10, because this project was working well before...
EDIT : it also seems to failed when using a project with -
in project name…
How can I use SUM() OVER()
if you are using SQL 2012 you should try
SELECT ID,
AccountID,
Quantity,
SUM(Quantity) OVER (PARTITION BY AccountID ORDER BY AccountID rows between unbounded preceding and current row ) AS TopBorcT,
FROM tCariH
if available, better order by date column.
Get current url in Angular
With pure JavaScript:
console.log(window.location.href)
Using Angular:
this.router.url
import { Component } from '@angular/core';
import { Router } from '@angular/router';
@Component({
template: 'The href is: {{href}}'
/*
Other component settings
*/
})
export class Component {
public href: string = "";
constructor(private router: Router) {}
ngOnInit() {
this.href = this.router.url;
console.log(this.router.url);
}
}
The plunkr is here: https://plnkr.co/edit/0x3pCOKwFjAGRxC4hZMy?p=preview
Extract values in Pandas value_counts()
The best way to extract the values is to just do the following
json.loads(dataframe[column].value_counts().to_json())
This returns a dictionary which you can use like any other dict. Using values or keys.
{"apple": 5, "sausage": 2, "banana": 2, "cheese": 1}
Type or namespace name does not exist
I encountered this problem while using Visual Studio's Git integration to manage the project. For some reason the Windows Phone 8 project would compile just fine when targeting x86, but when I set it to target ARM, it would fail compiling with an error indicating that "Advertising" didn't exist in the Microsoft namespace.
I ended up resolving the issue by removing the Microsoft.Advertising.*.dll reference and adding it again.
How can I check if a jQuery plugin is loaded?
for the plugins that doesn't use fn namespace (for example pnotify), this works:
if($.pluginname) {
alert("plugin loaded");
} else {
alert("plugin not loaded");
}
This doesn't work:
if($.fn.pluginname)
How to check if a variable is set in Bash?
After skimming all the answers, this also works:
if [[ -z $SOME_VAR ]]; then read -p "Enter a value for SOME_VAR: " SOME_VAR; fi
echo "SOME_VAR=$SOME_VAR"
if you don't put SOME_VAR
instead of what I have $SOME_VAR
, it will set it to an empty value; $
is necessary for this to work.
Assertion failure in dequeueReusableCellWithIdentifier:forIndexPath:
Although this question is fairly old, there is another possibility:
If you are using Storyboards, you simply have to set the CellIdentifier in the Storyboard.
So if your CellIdentifier is "Cell", just set the "Identifier" property:
![enter image description here](https://i.stack.imgur.com/uBGUN.png)
Make sure to clean your build after doing so. XCode sometimes has some issues with Storyboard updates
Please add a @Pipe/@Directive/@Component annotation. Error
Another solution is below way and It was my fault that when happened I put HomeService
in declaration section in app.module.ts
whereas I should put HomeService
in Providers section that as you see below HomeService
in declaration:[]
is not in a correct place and HomeService
is in Providers :[]
section in a correct place that should be.
import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { HttpModule } from '@angular/http';
import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
import { HomeComponent } from './components/home/home.component';
import { HomeService } from './components/home/home.service';
@NgModule({
declarations: [
AppComponent,
HomeComponent,
HomeService // You will get error here
],
imports: [
BrowserModule,
BrowserAnimationsModule,
AppRoutingModule
],
providers: [
HomeService // Right place to set HomeService
],
bootstrap: [AppComponent]
})
export class AppModule { }
hope this help you.
Add unique constraint to combination of two columns
This can also be done in the GUI:
- Under the table "Person", right click Indexes
- Click/hover New Index
- Click Non-Clustered Index...
![enter image description here](https://i.stack.imgur.com/ds2cO.png)
- A default Index name will be given but you may want to change it.
- Check Unique checkbox
- Click Add... button
![enter image description here](https://i.stack.imgur.com/98Bwm.png)
- Check the columns you want included
![enter image description here](https://i.stack.imgur.com/2MtYi.png)
- Click OK in each window.
How to write Unicode characters to the console?
I found some elegant solution on MSDN
System.Console.Write('\uXXXX') //XXXX is hex Unicode for character
This simple program writes ? right on the screen.
using System;
public class Test
{
public static void Main()
{
Console.Write('\u2103'); //? character code
}
}
Javascript onHover event
I don't think you need/want the timeout.
onhover (hover) would be defined as the time period while "over" something. IMHO
onmouseover = start...
onmouseout = ...end
For the record I've done some stuff with this to "fake" the hover event in IE6. It was rather expensive and in the end I ditched it in favor of performance.
How do I execute a command and get the output of the command within C++ using POSIX?
For Windows, popen
also works, but it opens up a console window - which quickly flashes over your UI application. If you want to be a professional, it's better to disable this "flashing" (especially if the end-user can cancel it).
So here is my own version for Windows:
(This code is partially recombined from ideas written in The Code Project and MSDN samples.)
#include <windows.h>
#include <atlstr.h>
//
// Execute a command and get the results. (Only standard output)
//
CStringA ExecCmd(
const wchar_t* cmd // [in] command to execute
)
{
CStringA strResult;
HANDLE hPipeRead, hPipeWrite;
SECURITY_ATTRIBUTES saAttr = {sizeof(SECURITY_ATTRIBUTES)};
saAttr.bInheritHandle = TRUE; // Pipe handles are inherited by child process.
saAttr.lpSecurityDescriptor = NULL;
// Create a pipe to get results from child's stdout.
if (!CreatePipe(&hPipeRead, &hPipeWrite, &saAttr, 0))
return strResult;
STARTUPINFOW si = {sizeof(STARTUPINFOW)};
si.dwFlags = STARTF_USESHOWWINDOW | STARTF_USESTDHANDLES;
si.hStdOutput = hPipeWrite;
si.hStdError = hPipeWrite;
si.wShowWindow = SW_HIDE; // Prevents cmd window from flashing.
// Requires STARTF_USESHOWWINDOW in dwFlags.
PROCESS_INFORMATION pi = { 0 };
BOOL fSuccess = CreateProcessW(NULL, (LPWSTR)cmd, NULL, NULL, TRUE, CREATE_NEW_CONSOLE, NULL, NULL, &si, &pi);
if (! fSuccess)
{
CloseHandle(hPipeWrite);
CloseHandle(hPipeRead);
return strResult;
}
bool bProcessEnded = false;
for (; !bProcessEnded ;)
{
// Give some timeslice (50 ms), so we won't waste 100% CPU.
bProcessEnded = WaitForSingleObject( pi.hProcess, 50) == WAIT_OBJECT_0;
// Even if process exited - we continue reading, if
// there is some data available over pipe.
for (;;)
{
char buf[1024];
DWORD dwRead = 0;
DWORD dwAvail = 0;
if (!::PeekNamedPipe(hPipeRead, NULL, 0, NULL, &dwAvail, NULL))
break;
if (!dwAvail) // No data available, return
break;
if (!::ReadFile(hPipeRead, buf, min(sizeof(buf) - 1, dwAvail), &dwRead, NULL) || !dwRead)
// Error, the child process might ended
break;
buf[dwRead] = 0;
strResult += buf;
}
} //for
CloseHandle(hPipeWrite);
CloseHandle(hPipeRead);
CloseHandle(pi.hProcess);
CloseHandle(pi.hThread);
return strResult;
} //ExecCmd
disable Bootstrap's Collapse open/close animation
If you find the 1px jump before expanding and after collapsing when using the CSS solution a bit annoying, here's a simple JavaScript solution for Bootstrap 3...
Just add this somewhere in your code:
$(document).ready(
$('.collapse').on('show.bs.collapse hide.bs.collapse', function(e) {
e.preventDefault();
}),
$('[data-toggle="collapse"]').on('click', function(e) {
e.preventDefault();
$($(this).data('target')).toggleClass('in');
})
);
List submodules in a Git repository
Just the submodule paths please, ma'am...
git config --list | grep \^submodule | cut -f 2 -d .
Vendor/BaseModel
Vendor/ObjectMatcher
Vendor/OrderedDictionary
Vendor/_ObjC
Vendor/XCodeHelpers
Find specific string in a text file with VBS script
Try to change like this ..
firstStr = "<?xml version" 'my file always starts like this
Do until objInputFile.AtEndOfStream
strToAdd = "<tr><td><a href=" & chr(34) & "../../Logs/DD/Beginning_of_DD_TC" & CStr(index) & ".html" & chr(34) & ">Beginning_of_DD_TC" & CStr(index) & "</a></td></tr>"
substrToFind = "<tr><td><a href=" & chr(34) & "../Test case " & trim(cstr((index)))
tmpStr = objInputFile.ReadLine
If InStr(tmpStr, substrToFind) <= 0 Then
If Instr(tmpStr, firstStr) > 0 Then
text = tmpStr 'to avoid the first empty line
Else
text = text & vbCrLf & tmpStr
End If
Else
text = text & vbCrLf & strToAdd & vbCrLf & tmpStr
End If
index = index + 1
Loop
horizontal scrollbar on top and bottom of table
Without JQuery (2017)
Because you might not need JQuery, here is a working Vanilla JS version based on @StanleyH answer:
_x000D_
_x000D_
var wrapper1 = document.getElementById('wrapper1');_x000D_
var wrapper2 = document.getElementById('wrapper2');_x000D_
wrapper1.onscroll = function() {_x000D_
wrapper2.scrollLeft = wrapper1.scrollLeft;_x000D_
};_x000D_
wrapper2.onscroll = function() {_x000D_
wrapper1.scrollLeft = wrapper2.scrollLeft;_x000D_
};
_x000D_
#wrapper1, #wrapper2{width: 300px; border: none 0px RED;_x000D_
overflow-x: scroll; overflow-y:hidden;}_x000D_
#wrapper1{height: 20px; }_x000D_
#wrapper2{height: 100px; }_x000D_
#div1 {width:1000px; height: 20px; }_x000D_
#div2 {width:1000px; height: 100px; background-color: #88FF88;_x000D_
overflow: auto;}
_x000D_
<div id="wrapper1">_x000D_
<div id="div1">_x000D_
</div>_x000D_
</div>_x000D_
<div id="wrapper2">_x000D_
<div id="div2">_x000D_
aaaa bbbb cccc dddd aaaa bbbb cccc _x000D_
dddd aaaa bbbb cccc dddd aaaa bbbb _x000D_
cccc dddd aaaa bbbb cccc dddd aaaa _x000D_
bbbb cccc dddd aaaa bbbb cccc dddd_x000D_
</div>_x000D_
</div>
_x000D_
_x000D_
_x000D_
What is the difference between readonly="true" & readonly="readonly"?
readonly="true"
is invalid HTML5, readonly="readonly"
is valid.
HTML5 spec:
http://www.w3.org/TR/html5/forms.html#attr-input-readonly :
The readonly attribute is a boolean attribute
http://www.w3.org/TR/html5/infrastructure.html#boolean-attributes :
The presence of a boolean attribute on an element represents the true value, and the absence of the attribute represents the false value.
If the attribute is present, its value must either be the empty string or a value that is an ASCII case-insensitive match for the attribute's canonical name, with no leading or trailing whitespace.
Conclusion:
The following are valid, equivalent and true:
<input type="text" readonly />
<input type="text" readonly="" />
<input type="text" readonly="readonly" />
<input type="text" readonly="ReAdOnLy" />
The following are invalid:
<input type="text" readonly="0" />
<input type="text" readonly="1" />
<input type="text" readonly="false" />
<input type="text" readonly="true" />
The absence of the attribute is the only valid syntax for false:
<input type="text"/>
Recommendation
If you care about writing valid XHTML, use readonly="readonly"
, since <input readonly>
is invalid and other alternatives are less readable. Else, just use <input readonly>
as it is shorter.
Sort tuples based on second parameter
And if you are using python 3.X, you may apply the sorted
function on the mylist. This is just an addition to the answer that @Sven Marnach has given above.
# using *sort method*
mylist.sort(lambda x: x[1])
# using *sorted function*
sorted(mylist, key = lambda x: x[1])
How to find out what character key is pressed?
Try:
_x000D_
_x000D_
<table>_x000D_
<tr><td>Key:</td><td id="key"></td></tr>_x000D_
<tr><td>Key Code:</td><td id="keyCode"></td></tr>_x000D_
<tr><td>Event Code:</td><td id="eventCode"></td></tr>_x000D_
</table>_x000D_
<script type="text/javascript">_x000D_
window.addEventListener("keydown", function (e) {_x000D_
//tested in IE/Chrome/Firefox_x000D_
document.getElementById("key").innerHTML = e.key;_x000D_
document.getElementById("keyCode").innerHTML = e.keyCode;_x000D_
document.getElementById("eventCode").innerHTML = e.code;_x000D_
})_x000D_
</script>
_x000D_
_x000D_
_x000D_
*Note: this works in "Run code snippet"
This website does the same as my code above: Keycode.info
Getting time elapsed in Objective-C
The other answers are correct (with a caveat*). I add this answer simply to show an example usage:
- (void)getYourAffairsInOrder
{
NSDate* methodStart = [NSDate date]; // Capture start time.
// … Do some work …
NSLog(@"DEBUG Method %s ran. Elapsed: %f seconds.", __func__, -([methodStart timeIntervalSinceNow])); // Calculate and report elapsed time.
}
On the debugger console, you see something like this:
DEBUG Method '-[XMAppDelegate getYourAffairsInOrder]' ran. Elapsed: 0.033827 seconds.
*Caveat: As others mentioned, use NSDate
to calculate elapsed time only for casual purposes. One such purpose might be common testing, crude profiling, where you just want a rough idea of how long a method is taking.
The risk is that the device's clock's current time setting could change at any moment because of network clock syncing. So NSDate
time could jump forward or backward at any moment.
Git command to show which specific files are ignored by .gitignore
Another option that's pretty clean (No pun intended.):
git clean -ndX
Explanation:
$ git help clean
git-clean - Remove untracked files from the working tree
-n, --dry-run - Don't actually remove anything, just show what would be done.
-d - Remove untracked directories in addition to untracked files.
-X - Remove only files ignored by Git.
Note: This solution will not show ignored files that have already been removed.
How can I replace a newline (\n) using sed?
It is sed that introduces the new-lines after "normal" substitution. First, it trims the new-line char, then it processes according to your instructions, then it introduces a new-line.
Using sed you can replace "the end" of a line (not the new-line char) after being trimmed, with a string of your choice, for each input line; but, sed will output different lines. For example, suppose you wanted to replace the "end of line" with "===" (more general than a replacing with a single space):
PROMPT~$ cat <<EOF |sed 's/$/===/g'
first line
second line
3rd line
EOF
first line===
second line===
3rd line===
PROMPT~$
To replace the new-line char with the string, you can, inefficiently though, use tr , as pointed before, to replace the newline-chars with a "special char" and then use sed to replace that special char with the string you want.
For example:
PROMPT~$ cat <<EOF | tr '\n' $'\x01'|sed -e 's/\x01/===/g'
first line
second line
3rd line
EOF
first line===second line===3rd line===PROMPT~$
Override devise registrations controller
Very simple methods
Just go to the terminal and the type following
rails g devise:controllers users //This will create devise controllers in controllers/users folder
Next to use custom views
rails g devise:views users //This will create devise views in views/users folder
now in your route.rb file
devise_for :users, controllers: {
:sessions => "users/sessions",
:registrations => "users/registrations" }
You can add other controllers too. This will make devise to use controllers in users folder and views in users folder.
Now you can customize your views as your desire and add your logic to controllers in controllers/users folder.
Enjoy !
How to Install Windows Phone 8 SDK on Windows 7
You can install it by first extracting all the files from the ISO and then overwriting those files with the files from the ZIP. Then you can run the batch file as administrator to do the installation. Most of the packages install on windows 7, but I haven't tested yet how well they work.
Convert base64 string to image
Server side encoding files/Images to base64String ready for client side consumption
public Optional<String> InputStreamToBase64(Optional<InputStream> inputStream) throws IOException{
if (inputStream.isPresent()) {
ByteArrayOutputStream output = new ByteArrayOutputStream();
FileCopyUtils.copy(inputStream.get(), output);
//TODO retrieve content type from file, & replace png below with it
return Optional.ofNullable("data:image/png;base64," + DatatypeConverter.printBase64Binary(output.toByteArray()));
}
return Optional.empty();
}
Server side base64 Image/File decoder
public Optional<InputStream> Base64InputStream(Optional<String> base64String)throws IOException {
if (base64String.isPresent()) {
return Optional.ofNullable(new ByteArrayInputStream(DatatypeConverter.parseBase64Binary(base64String.get())));
}
return Optional.empty();
}
jQuery - Check if DOM element already exists
(()=> {
var elem = document.querySelector('.elem');
(
(elem) ?
console.log(elem+' was found.') :
console.log('not found')
)
})();
If it exists, it spits out the specified element as a DOM object. With JQuery $('.elem')
it only tells you that it's an object if found but not which.
Adjust icon size of Floating action button (fab)
If you are using androidx 1.0.0 and are using a custom fab size, you will have to specify the custom size using
app:fabCustomSize="your custom size in dp"
By deafult the size is 56dp and there is another variation that is the small sized fab which is 40dp, if you are using anything you will have to specify it for the padding to be calculated correctly
How to set zoom level in google map
What you're looking for are the scales for each zoom level. The numbers are in metres. Use these:
20 : 1128.497220
19 : 2256.994440
18 : 4513.988880
17 : 9027.977761
16 : 18055.955520
15 : 36111.911040
14 : 72223.822090
13 : 144447.644200
12 : 288895.288400
11 : 577790.576700
10 : 1155581.153000
9 : 2311162.307000
8 : 4622324.614000
7 : 9244649.227000
6 : 18489298.450000
5 : 36978596.910000
4 : 73957193.820000
3 : 147914387.600000
2 : 295828775.300000
1 : 591657550.500000
What's the best way to determine the location of the current PowerShell script?
PowerShell 3+
# This is an automatic variable set to the current file's/module's directory
$PSScriptRoot
PowerShell 2
Prior to PowerShell 3, there was not a better way than querying the
MyInvocation.MyCommand.Definition
property for general scripts. I had the following line at the top of essentially every PowerShell script I had:
$scriptPath = split-path -parent $MyInvocation.MyCommand.Definition
Synchronization vs Lock
Brian Goetz's "Java Concurrency In Practice" book, section 13.3:
"...Like the default ReentrantLock, intrinsic locking offers no deterministic fairness guarantees, but the
statistical fairness guarantees of most locking implementations are good enough for almost all situations..."
How to set the action for a UIBarButtonItem in Swift
As of Swift 2.2, there is a special syntax for compiler-time checked selectors. It uses the syntax: #selector(methodName)
.
Swift 3 and later:
var b = UIBarButtonItem(
title: "Continue",
style: .plain,
target: self,
action: #selector(sayHello(sender:))
)
func sayHello(sender: UIBarButtonItem) {
}
If you are unsure what the method name should look like, there is a special version of the copy command that is very helpful. Put your cursor somewhere in the base method name (e.g. sayHello) and press Shift+Control+Option+C. That puts the ‘Symbol Name’ on your keyboard to be pasted. If you also hold Command it will copy the ‘Qualified Symbol Name’ which will include the type as well.
Swift 2.3:
var b = UIBarButtonItem(
title: "Continue",
style: .Plain,
target: self,
action: #selector(sayHello(_:))
)
func sayHello(sender: UIBarButtonItem) {
}
This is because the first parameter name is not required in Swift 2.3 when making a method call.
You can learn more about the syntax on swift.org here: https://swift.org/blog/swift-2-2-new-features/#compile-time-checked-selectors
What are the differences among grep, awk & sed?
Short definition:
grep
: search for specific terms in a file
#usage
$ grep This file.txt
Every line containing "This"
Every line containing "This"
Every line containing "This"
Every line containing "This"
$ cat file.txt
Every line containing "This"
Every line containing "This"
Every line containing "That"
Every line containing "This"
Every line containing "This"
Now awk
and sed
are completly different than grep
.
awk
and sed
are text processors. Not only do they have the ability to find what you are looking for in text, they have the ability to remove, add and modify the text as well (and much more).
awk
is mostly used for data extraction and reporting. sed
is a stream editor
Each one of them has its own functionality and specialties.
Example
Sed
$ sed -i 's/cat/dog/' file.txt
# this will replace any occurrence of the characters 'cat' by 'dog'
Awk
$ awk '{print $2}' file.txt
# this will print the second column of file.txt
Basic awk
usage:
Compute sum/average/max/min/etc. what ever you may need.
$ cat file.txt
A 10
B 20
C 60
$ awk 'BEGIN {sum=0; count=0; OFS="\t"} {sum+=$2; count++} END {print "Average:", sum/count}' file.txt
Average: 30
I recommend that you read this book: Sed & Awk: 2nd Ed.
It will help you become a proficient sed/awk user on any unix-like environment.
Matplotlib - Move X-Axis label downwards, but not X-Axis Ticks
If the variable ax.xaxis._autolabelpos = True, matplotlib sets the label position in function _update_label_position in axis.py according to (some excerpts):
bboxes, bboxes2 = self._get_tick_bboxes(ticks_to_draw, renderer)
bbox = mtransforms.Bbox.union(bboxes)
bottom = bbox.y0
x, y = self.label.get_position()
self.label.set_position((x, bottom - self.labelpad * self.figure.dpi / 72.0))
You can set the label position independently of the ticks by using:
ax.xaxis.set_label_coords(x0, y0)
that sets _autolabelpos to False or as mentioned above by changing the labelpad parameter.
How to convert DOS/Windows newline (CRLF) to Unix newline (LF) in a Bash script?
An even simpler awk solution w/o a program:
awk -v ORS='\r\n' '1' unix.txt > dos.txt
Technically '1' is your program, b/c awk requires one when given option.
UPDATE:
After revisiting this page for the first time in a long time I realized that no one has yet posted an internal solution, so here is one:
while IFS= read -r line;
do printf '%s\n' "${line%$'\r'}";
done < dos.txt > unix.txt
Can I bind an array to an IN() condition?
very clean way for postgres is using the postgres-array ("{}"):
$ids = array(1,4,7,9,45);
$param = "{".implode(', ',$ids)."}";
$cmd = $db->prepare("SELECT * FROM table WHERE id = ANY (?)");
$result = $cmd->execute(array($param));
qmake: could not find a Qt installation of ''
Install qt using:
sudo apt install qt5-qmake
Open ~/.bashrc
file:
vim ~/.bashrc
Added the path below to the ~/.bashrc
file:
export PATH="/opt/Qt/5.15.1/gcc_64/bin/:$PATH"
Execute/load a ~/.bashrc
file in your current shell
source ~/.bashrc`
Try now qmake
by using the version command below:
qmake --version
Detect Windows version in .net
This is a relatively old question but I've recently had to solve this problem and didn't see my solution posted anywhere.
The easiest (and simplest way in my opinion) is to just use a pinvoke call to RtlGetVersion
[DllImport("ntdll.dll", SetLastError = true)]
internal static extern uint RtlGetVersion(out Structures.OsVersionInfo versionInformation); // return type should be the NtStatus enum
[StructLayout(LayoutKind.Sequential)]
internal struct OsVersionInfo
{
private readonly uint OsVersionInfoSize;
internal readonly uint MajorVersion;
internal readonly uint MinorVersion;
private readonly uint BuildNumber;
private readonly uint PlatformId;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
private readonly string CSDVersion;
}
Where Major and Minor version numbers in this struct correspond to the values in the table of the accepted answer.
This returns the correct Windows version number unlike the deprecated GetVersion & GetVersionEx functions from kernel32
Why do we use __init__ in Python classes?
By what you wrote, you are missing a critical piece of understanding: the difference between a class and an object. __init__
doesn't initialize a class, it initializes an instance of a class or an object. Each dog has colour, but dogs as a class don't. Each dog has four or fewer feet, but the class of dogs doesn't. The class is a concept of an object. When you see Fido and Spot, you recognise their similarity, their doghood. That's the class.
When you say
class Dog:
def __init__(self, legs, colour):
self.legs = legs
self.colour = colour
fido = Dog(4, "brown")
spot = Dog(3, "mostly yellow")
You're saying, Fido is a brown dog with 4 legs while Spot is a bit of a cripple and is mostly yellow. The __init__
function is called a constructor, or initializer, and is automatically called when you create a new instance of a class. Within that function, the newly created object is assigned to the parameter self
. The notation self.legs
is an attribute called legs
of the object in the variable self
. Attributes are kind of like variables, but they describe the state of an object, or particular actions (functions) available to the object.
However, notice that you don't set colour
for the doghood itself - it's an abstract concept. There are attributes that make sense on classes. For instance, population_size
is one such - it doesn't make sense to count the Fido because Fido is always one. It does make sense to count dogs. Let us say there're 200 million dogs in the world. It's the property of the Dog class. Fido has nothing to do with the number 200 million, nor does Spot. It's called a "class attribute", as opposed to "instance attributes" that are colour
or legs
above.
Now, to something less canine and more programming-related. As I write below, class to add things is not sensible - what is it a class of? Classes in Python make up of collections of different data, that behave similarly. Class of dogs consists of Fido and Spot and 199999999998 other animals similar to them, all of them peeing on lampposts. What does the class for adding things consist of? By what data inherent to them do they differ? And what actions do they share?
However, numbers... those are more interesting subjects. Say, Integers. There's a lot of them, a lot more than dogs. I know that Python already has integers, but let's play dumb and "implement" them again (by cheating and using Python's integers).
So, Integers are a class. They have some data (value), and some behaviours ("add me to this other number"). Let's show this:
class MyInteger:
def __init__(self, newvalue)
# imagine self as an index card.
# under the heading of "value", we will write
# the contents of the variable newvalue.
self.value = newvalue
def add(self, other):
# when an integer wants to add itself to another integer,
# we'll take their values and add them together,
# then make a new integer with the result value.
return MyInteger(self.value + other.value)
three = MyInteger(3)
# three now contains an object of class MyInteger
# three.value is now 3
five = MyInteger(5)
# five now contains an object of class MyInteger
# five.value is now 5
eight = three.add(five)
# here, we invoked the three's behaviour of adding another integer
# now, eight.value is three.value + five.value = 3 + 5 = 8
print eight.value
# ==> 8
This is a bit fragile (we're assuming other
will be a MyInteger), but we'll ignore now. In real code, we wouldn't; we'd test it to make sure, and maybe even coerce it ("you're not an integer? by golly, you have 10 nanoseconds to become one! 9... 8....")
We could even define fractions. Fractions also know how to add themselves.
class MyFraction:
def __init__(self, newnumerator, newdenominator)
self.numerator = newnumerator
self.denominator = newdenominator
# because every fraction is described by these two things
def add(self, other):
newdenominator = self.denominator * other.denominator
newnumerator = self.numerator * other.denominator + self.denominator * other.numerator
return MyFraction(newnumerator, newdenominator)
There's even more fractions than integers (not really, but computers don't know that). Let's make two:
half = MyFraction(1, 2)
third = MyFraction(1, 3)
five_sixths = half.add(third)
print five_sixths.numerator
# ==> 5
print five_sixths.denominator
# ==> 6
You're not actually declaring anything here. Attributes are like a new kind of variable. Normal variables only have one value. Let us say you write colour = "grey"
. You can't have another variable named colour
that is "fuchsia"
- not in the same place in the code.
Arrays solve that to a degree. If you say colour = ["grey", "fuchsia"]
, you have stacked two colours into the variable, but you distinguish them by their position (0, or 1, in this case).
Attributes are variables that are bound to an object. Like with arrays, we can have plenty colour
variables, on different dogs. So, fido.colour
is one variable, but spot.colour
is another. The first one is bound to the object within the variable fido
; the second, spot
. Now, when you call Dog(4, "brown")
, or three.add(five)
, there will always be an invisible parameter, which will be assigned to the dangling extra one at the front of the parameter list. It is conventionally called self
, and will get the value of the object in front of the dot. Thus, within the Dog's __init__
(constructor), self
will be whatever the new Dog will turn out to be; within MyInteger
's add
, self
will be bound to the object in the variable three
. Thus, three.value
will be the same variable outside the add
, as self.value
within the add
.
If I say the_mangy_one = fido
, I will start referring to the object known as fido
with yet another name. From now on, fido.colour
is exactly the same variable as the_mangy_one.colour
.
So, the things inside the __init__
. You can think of them as noting things into the Dog's birth certificate. colour
by itself is a random variable, could contain anything. fido.colour
or self.colour
is like a form field on the Dog's identity sheet; and __init__
is the clerk filling it out for the first time.
Any clearer?
EDIT: Expanding on the comment below:
You mean a list of objects, don't you?
First of all, fido
is actually not an object. It is a variable, which is currently containing an object, just like when you say x = 5
, x
is a variable currently containing the number five. If you later change your mind, you can do fido = Cat(4, "pleasing")
(as long as you've created a class Cat
), and fido
would from then on "contain" a cat object. If you do fido = x
, it will then contain the number five, and not an animal object at all.
A class by itself doesn't know its instances unless you specifically write code to keep track of them. For instance:
class Cat:
census = [] #define census array
def __init__(self, legs, colour):
self.colour = colour
self.legs = legs
Cat.census.append(self)
Here, census
is a class-level attribute of Cat
class.
fluffy = Cat(4, "white")
spark = Cat(4, "fiery")
Cat.census
# ==> [<__main__.Cat instance at 0x108982cb0>, <__main__.Cat instance at 0x108982e18>]
# or something like that
Note that you won't get [fluffy, sparky]
. Those are just variable names. If you want cats themselves to have names, you have to make a separate attribute for the name, and then override the __str__
method to return this name. This method's (i.e. class-bound function, just like add
or __init__
) purpose is to describe how to convert the object to a string, like when you print it out.
How do I configure Maven for offline development?
You can run maven in offline mode mvn -o install
. Of course any artifacts not available in your local repository will fail. Maven is not predicated on distributed repositories, but they certainly make things more seamless. Its for this reason that many shops use internal mirrors that are incrementally synced with the central repos.
In addition, the mvn dependency:go-offline
can be used to ensure you have all of your dependencies installed locally before you begin to work offline.
How to send Request payload to REST API in java?
I tried with a rest client.
Headers :
- POST /r/gerrit/rpc/ChangeDetailService HTTP/1.1
- Host: git.eclipse.org
- User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:18.0) Gecko/20100101 Firefox/18.0
- Accept: application/json
- Accept-Language: null
- Accept-Encoding: gzip,deflate,sdch
- accept-charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3
- Content-Type: application/json; charset=UTF-8
- Content-Length: 73
- Connection: keep-alive
it works fine. I retrieve 200 OK with a good body.
Why do you set a status code in your request?
and multiple declaration "Accept" with Accept:application/json,application/json,application/jsonrequest. just a statement is enough.
How to clear Facebook Sharer cache?
Facebook treats each url as unique and caches the page based on that url, so if you want to share the latest url the simplest solution is to add a query string with the url being shared. In simple words just add ?v=1 at the end of the url. Any number can be used in place of 1.
Hat tip: Umair Jabbar
How to add link to flash banner
If you have a flash FLA file that shows the FLV movie you can add a button inside the FLA file. This button can be given an action to load the URL.
on (release) {
getURL("http://someurl/");
}
To make the button transparent you can place a square inside it that is moved to the hit-area frame of the button.
I think it would go too far to explain into depth with pictures how to go about in stackoverflow.
How to install crontab on Centos
As seen in Install crontab on CentOS, the crontab package in CentOS is vixie-cron
. Hence, do install it with:
yum install vixie-cron
And then start it with:
service crond start
To make it persistent, so that it starts on boot, use:
chkconfig crond on
On CentOS 7 you need to use cronie
:
yum install cronie
On CentOS 6 you can install vixie-cron
, but the real package is cronie
:
yum install vixie-cron
and
yum install cronie
In both cases you get the same output:
.../...
==================================================================
Package Arch Version Repository Size
==================================================================
Installing:
cronie x86_64 1.4.4-12.el6 base 73 k
Installing for dependencies:
cronie-anacron x86_64 1.4.4-12.el6 base 30 k
crontabs noarch 1.10-33.el6 base 10 k
exim x86_64 4.72-6.el6 epel 1.2 M
Transaction Summary
==================================================================
Install 4 Package(s)
Getting windbg without the whole WDK?
Actually, Microsoft has now made the Debugging Tools downloadable separately from the SDK. Look for the section "Standalone Debugging Tools for Windows (WinDbg)" about mid-page:
@Media min-width & max-width
The correct value for the content
attribute should include initial-scale
instead:
_x000D_
_x000D_
<meta name="viewport" content="width=device-width, initial-scale=1">_x000D_
^^^^^^^^^^^^^^^
_x000D_
_x000D_
_x000D_
Windows task scheduler error 101 launch failure code 2147943785
Had the same issue today. I added the user to:
Administrative Tools -> Local Security Policy -> Local Policies -> User Rights Assignment -> Log on as a batch job
But was still getting the error. I found this post, and it turns out there's also this setting that I had to remove the user from (not sure how it got in there):
Administrative Tools -> Local Security Policy -> Local Policies -> User Rights Assignment -> Deny log on as a batch job
So just be aware that you may need to check both policies for the user.
How can I get phone serial number (IMEI)
public String getIMEI(Context context){
TelephonyManager mngr = (TelephonyManager) context.getSystemService(context.TELEPHONY_SERVICE);
String imei = mngr.getDeviceId();
return imei;
}
Is mongodb running?
You can use the below command, to check MongoDB status, e.g: sudo service MongoDB status
which displays the status of MongoDB service as like the screenshot:
![MongoDB status](https://i.stack.imgur.com/6gGdn.png)
Normalization in DOM parsing with java - how does it work?
The rest of the sentence is:
where only structure (e.g., elements, comments, processing instructions, CDATA sections, and entity references) separates Text nodes, i.e., there are neither adjacent Text nodes nor empty Text nodes.
This basically means that the following XML element
<foo>hello
wor
ld</foo>
could be represented like this in a denormalized node:
Element foo
Text node: ""
Text node: "Hello "
Text node: "wor"
Text node: "ld"
When normalized, the node will look like this
Element foo
Text node: "Hello world"
And the same goes for attributes: <foo bar="Hello world"/>
, comments, etc.
How can I specify the default JVM arguments for programs I run from eclipse?
Go to Window → Preferences → Java → Installed JREs. Select the JRE you're using, click Edit, and there will be a line for Default VM Arguments which will apply to every execution. For instance, I use this on OS X to hide the icon from the dock, increase max memory and turn on assertions:
-Xmx512m -ea -Djava.awt.headless=true
What is the difference between typeof and instanceof and when should one be used vs. the other?
A good reason to use typeof is if the variable may be undefined.
alert(typeof undefinedVariable); // alerts the string "undefined"
alert(undefinedVariable instanceof Object); // throws an exception
A good reason to use instanceof is if the variable may be null.
var myNullVar = null;
alert(typeof myNullVar ); // alerts the string "object"
alert(myNullVar instanceof Object); // alerts "false"
So really in my opinion it would depend on what type of possible data you are checking.
Can't find/install libXtst.so.6?
EDIT: As mentioned by Stephen Niedzielski in his comment, the issue seems to come from the 32-bit being of the JRE, which is de facto, looking for the 32-bit version of libXtst6
. To install the required version of the library:
$ sudo apt-get install libxtst6:i386
Type:
$ sudo apt-get update
$ sudo apt-get install libxtst6
If this isn’t OK, type:
$ sudo updatedb
$ locate libXtst
it should return something like:
/usr/lib/x86_64-linux-gnu/libXtst.so.6 # Mine is OK
/usr/lib/x86_64-linux-gnu/libXtst.so.6.1.0
If you do not have libXtst.so.6
but do have libXtst.so.6.X.X
create a symbolic link:
$ cd /usr/lib/x86_64-linux-gnu/
$ ln -s libXtst.so.6 libXtst.so.6.X.X
Hope this helps.
Is " " a replacement of " "?
is the character entity reference (meant to be easily parseable by humans).
 
is the numeric entity reference (meant to be easily parseable by machines).
They are the same except for the fact that the latter does not need another lookup table to find its actual value. The lookup table is called a DTD, by the way.
You can read more about character entity references in the offical W3C documents.
How to sort ArrayList<Long> in decreasing order?
You can also sort an ArrayList
with a TreeSet
instead of a comparator
. Here's an example from a question I had before for an integer array. I'm using "numbers" as a placeholder name for the ArrayList
.
import.java.util.*;
class MyClass{
public static void main(String[] args){
Scanner input = new Scanner(System.in);
ArrayList<Integer> numbers = new ArrayList<Integer>();
TreeSet<Integer> ts = new TreeSet<Integer>(numbers);
numbers = new ArrayList<Integer>(ts);
System.out.println("\nThe numbers in ascending order are:");
for(int i=0; i<numbers.size(); i++)
System.out.print(numbers.get(i).intValue()+" ");
System.out.println("\nThe numbers in descending order are:");
for(int i=numbers.size()-1; i>=0; i--)
System.out.print(numbers.get(i).intValue()+" ");
}
}
Write Array to Excel Range
The kind of array definition seems the key:
In my case it is a one dimension array of 17 items which have to convert to a two dimension array
Defintion for columns:
object[,] Array = new object[17, 1];
Defintion for rows
object[,] Array= new object[1,17];
The code for value2 is in both cases the same
Excel.Range cell = activeWorksheet.get_Range(Range);
cell.Value2 = Array;
LG Georg
Where is body in a nodejs http.get response?
The body is not fully stored as part of the response, the reason for this is because the body can contain a very large amount of data, if it was to be stored on the response object, the program's memory would be consumed quite fast.
Instead, Node.js uses a mechanism called Stream. This mechanism allows holding only a small part of the data and allows the programmer to decide if to fully consume it in memory or use each part of the data as its flowing.
There are multiple ways how to fully consume the data into memory, since HTTP Response
is a readable stream, all readable methods are available on the res
object
listening to the "data"
event and saving the chunks passed to the callback
const chunks = []
res.on("data", (chunk) => {
chunks.push(chunk)
});
res.on("end", () => {
const body = Buffer.concat(chunks);
});
When using this approach you do not interfere with the behavior of the stream and you are only gathering the data as it is available to the application.
using the "readble"
event and calling res.read()
const chunks = [];
res.on("readable", () => {
let chunk;
while(null !== (chunk = res.read())){
chunks.push(chunk)
}
});
res.on("end", () => {
const body = Buffer.concat(chunks);
});
When going with this approach you are fully in charge of the stream flow and until res.read
is called no more data will be passed into the stream.
using an async iterator
const chunks = [];
for await (const chunk of readable) {
chunks.push(chunk);
}
const body = Buffer.concat(chunks);
This approach is similar to the "data" event
approach. It will just simplify the scoping and allow the entire process to happen in the same scope.
While as described, it is possible to fully consume data from the response it is always important to keep in mind if it is actually necessary to do so. In many cases, it is possible to simply direct the data to its destination without fully saving it into memory.
Node.js read streams, including HTTP response, have a built-in method for doing this, this method is called pipe
. The usage is quite simple, readStream.pipe(writeStream);
.
for example:
If the final destination of your data is the file system, you can simply open a write stream to the file system and then pipe
the data to ts destination.
const { createWriteStream } = require("fs");
const writeStream = createWriteStream("someFile");
res.pipe(writeStream);
Table and Index size in SQL Server
There is an extended stored procedure sp_spaceused
that gets this information out. It's fairly convoluted to do it from the data dictionary, but This link fans out to a script that does it. This stackoverflow question has some fan-out to information on the underlying data structures that you can use to construct estimates of table and index sizes for capcity planning.