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Some Of The Best Answers From Latest Asked Questions

Update some specific field of an entity in android Room

We need the primary key of that particular model that you want to update. For example:

 private fun update(Name: String?, Brand: String?) {
    val deviceEntity = remoteDao?.getRemoteId(Id)
    if (deviceEntity == null)
        remoteDao?.insertDevice(DeviceEntity(DeviceModel = DeviceName, DeviceBrand = DeviceBrand))
    else
        DeviceDao?.updateDevice(DeviceEntity(deviceEntity.id,remoteDeviceModel = DeviceName, DeviceBrand = DeviceBrand))
}

In this function, I am checking whether a particular entry exists in the database if exists pull the primary key which is id over here and perform update function.

This is the for fetching and update records:

@Query("SELECT * FROM ${DeviceDatabase.DEVICE_TABLE_NAME} WHERE ${DeviceDatabase.COLUMN_DEVICE_ID} = :DeviceId LIMIT 1")

fun getRemoteDeviceId(DeviceId: String?): DeviceEntity


@Update(onConflict = OnConflictStrategy.REPLACE)
fun updatDevice(item: DeviceEntity): Int

CSS Grid Layout not working in IE11 even with prefixes

The answer has been given by Faisal Khurshid and Michael_B already.
This is just an attempt to make a possible solution more obvious.

For IE11 and below you need to enable grid's older specification in the parent div e.g. body or like here "grid" like so:

.grid-parent{display:-ms-grid;}

then define the amount and width of the columns and rows like e.g. so:

.grid-parent{
  -ms-grid-columns: 1fr 3fr;
  -ms-grid-rows: 4fr;
}

finally you need to explicitly tell the browser where your element (item) should be placed in e.g. like so:

.grid-item-1{
  -ms-grid-column: 1;
  -ms-grid-row: 1;
}

.grid-item-2{
  -ms-grid-column: 2;
  -ms-grid-row: 1;
}

Unable to create migrations after upgrading to ASP.NET Core 2.0

No need for IDesignTimeDbContextFactory.

Run

add-migration initial -verbose

that will reveal the details under

An error occurred while accessing the IWebHost on class 'Program'. Continuing without the application service provider.

warning, which is the root cause of the problem.

In my case, problem was, having ApplicationRole : IdentityRole<int> and invoking services.AddIdentity<ApplicationUser, IdentityRole>() which was causing below error

System.ArgumentException: GenericArguments[1], 'Microsoft.AspNetCore.Identity.IdentityRole', 
on 'Microsoft.AspNetCore.Identity.EntityFrameworkCore.UserStore`9[TUser,TRole,TContext,
TKey,TUserClaim,TUserRole,TUserLogin,TUserToken,TRoleClaim]' violates the constraint of type 'TRole'.
---> System.TypeLoadException: GenericArguments[1], 'Microsoft.AspNetCore.Identity.IdentityRole', 
on 'Microsoft.AspNetCore.Identity.UserStoreBase`8[TUser,TRole,TKey,TUserClaim,
TUserRole,TUserLogin,TUserToken,TRoleClaim]' violates the constraint of type parameter 'TRole'.

Fixing a systemd service 203/EXEC failure (no such file or directory)

I think I found the answer:

In the .service file, I needed to add /bin/bash before the path to the script.

For example, for backup.service:

ExecStart=/bin/bash /home/user/.scripts/backup.sh

As opposed to:

ExecStart=/home/user/.scripts/backup.sh

I'm not sure why. Perhaps fish. On the other hand, I have another script running for my email, and the service file seems to run fine without /bin/bash. It does use default.target instead multi-user.target, though.

Most of the tutorials I came across don't prepend /bin/bash, but I then saw this SO answer which had it, and figured it was worth a try.

The service file executes the script, and the timer is listed in systemctl --user list-timers, so hopefully this will work.

Update: I can confirm that everything is working now.

Counting unique values in a column in pandas dataframe like in Qlik?

To count unique values in column, say hID of dataframe df, use:

len(df.hID.unique())

How to downgrade tensorflow, multiple versions possible?

If you have anaconda, you can just install desired version and conda will automatically downgrade the current package for you.

For example:

conda install tensorflow=1.1

Flutter: Trying to bottom-center an item in a Column, but it keeps left-aligning

Align is the way to go is you have only one child.

If you have more, consider doing something like this :

return new Column(
  crossAxisAlignment: CrossAxisAlignment.center,
  mainAxisSize: MainAxisSize.max,
  mainAxisAlignment: MainAxisAlignment.end,
  children: <Widget>[
      //your elements here
  ],
);

How do I stretch an image to fit the whole background (100% height x 100% width) in Flutter?

I think that for your purpose Flex could work better than Container():

new Flex(
    direction: Axis.vertical,
    children: <Widget>[
      Image.asset(asset.background)
    ],
   )

The current .NET SDK does not support targeting .NET Standard 2.0 error in Visual Studio 2017 update 15.3

make sure you download the x86 SDK instead of only the x64 SDK for visual studio.

"The POM for ... is missing, no dependency information available" even though it exists in Maven Repository

This is my solution, may be it can helps I use IntelliJ IDE. File -> Setting -> Maven -> Importing change JDK for importer to 1.8( you can change to lower, higher)

Django - Reverse for '' not found. '' is not a valid view function or pattern name

In my case, I don't put namespace_name in the url tag ex: {% url 'url_name or pattern name' %}. you have to specify the namespace_name like: {% url 'namespace_name:url_name or pattern name' %}.

Explanation: In project urls.py path('', include('blog.urls',namespace='blog')), and in app's urls.py you have to specify the app_name. like app_name = 'blog'. namespace_name is the app_name.

What is the difference between spark.sql.shuffle.partitions and spark.default.parallelism?

From the answer here, spark.sql.shuffle.partitions configures the number of partitions that are used when shuffling data for joins or aggregations.

spark.default.parallelism is the default number of partitions in RDDs returned by transformations like join, reduceByKey, and parallelize when not set explicitly by the user. Note that spark.default.parallelism seems to only be working for raw RDD and is ignored when working with dataframes.

If the task you are performing is not a join or aggregation and you are working with dataframes then setting these will not have any effect. You could, however, set the number of partitions yourself by calling df.repartition(numOfPartitions) (don't forget to assign it to a new val) in your code.


To change the settings in your code you can simply do:

sqlContext.setConf("spark.sql.shuffle.partitions", "300")
sqlContext.setConf("spark.default.parallelism", "300")

Alternatively, you can make the change when submitting the job to a cluster with spark-submit:

./bin/spark-submit --conf spark.sql.shuffle.partitions=300 --conf spark.default.parallelism=300

Search input with an icon Bootstrap 4

Here is an input box with a search icon on the right.

  <div class="input-group">
      <input class="form-control py-2 border-right-0 border" type="search" placeholder="Search">
      <div class="input-group-append">
          <div class="input-group-text" id="btnGroupAddon2"><i class="fa fa-search"></i></div>
      </div>
  </div>

Here is an input box with a search icon on the left.

  <div class="input-group">
      <div class="input-group-prepend">
          <div class="input-group-text" id="btnGroupAddon2"><i class="fa fa-search"></i></div>
      </div>
      <input class="form-control py-2 border-right-0 border" type="search" placeholder="Search">
  </div>

Failed to resolve: com.google.android.gms:play-services in IntelliJ Idea with gradle

I just replaced version 11.2.0 with 11.0.0 and then it seemed to work fine, so that had to mean that 11.2.0 wasn't included with the latest Android SDK.

So, after struggling with all the available scattered documentation, I reached this document by pure chance (I guess it is not indexed high enough by Google): https://developers.google.com/android/guides/releases

I quote from there:

Highlights from the Google Play services 11.2 release. Google Play services dependencies are now available via maven.google.com

Now, even when that shouldn't necessarily mean that they are not available with the downloaded SDK anymore, it seems that this is actually the case.

Anyway, adding google() to my build.gradle didn't work (not found, undefined, or whatever...), so I used a different approach that I found in this document referenced from the previous one:

https://developer.android.com/studio/build/dependencies.html#google-maven

I modified my build.gradle file adding that line to allprojects/repositories, as in:

allprojects {
...
    repositories {
...
        maven { url "https://maven.google.com/"}
    }
}

And then also in the android section in the same build.gradle file:

project(":android") {
...
    dependencies {
...
        compile 'com.google.android.gms:play-services-ads:11.2.0'
    }
}

Those two lines were enough to make Gradle sync without problems. I didn't need to add any plugins apart from the ones that are already added in my libGDX project by default.

After that, I got a few different errors, but none about Gradle or dependencies. In a brief, JFTR:

First, I had a minSdkVersion of 8. Solved by raising it to 14. I think I could live without supporting all those devices below 14.

Second, I had problems with the dex upper limit of references. I've never faced this problem before, but maybe you've already noticed the solution I used: instead of compiling the whole 'com.google.android.gms:play-services' I used only 'com.google.android.gms:play-services-ads' that's the API I'm actually interested right now. For those other particular cases where a solution like this may not be useful, this document could provide some better insight: https://developer.android.com/studio/build/multidex.html

Third, even after that I got this "jumbo" thing problem described and answered here: https://stackoverflow.com/a/26248495/1160360

And that's it. As of now, everything builds and my game does finally shows those Admob banners.

I've spent hours with this, thought, which makes me wonder if all these building automation systems we are using lately are worth the extra load they add.

I mean, the first time I had to add Admob to an app five years ago or so, I just had to download a .jar file and put it on a directory on my project. It was pretty obvious and the whole process, from googling "how to setup Admob in my android project" to have my app showing an Admob banner took me just a few minutes. I'm gonna leave it here, since this is not the place for such kind of debate.

Nonetheless, I hope my own experience is useful for someone else further.

How can I get a random number in Kotlin?

In Kotlin SDK >=1.3 you can do it like

import kotlin.random.Random

val number = Random.nextInt(limit)

docker : invalid reference format

The first argument after the "run" that is not a flag or parameter to a flag is parsed as an image name. When that parsing fails, it tells you the reference format, aka image name (but could be an image id, pinned image, or other syntax) is invalid. In your command:

 docker run -p 8888:8888 -v `pwd`/../src:/src -v `pwd`/../data:/data -w /src supervisely_anpr --rm -it bash

The image name "supervisely_anpr" is valid, so you need to look earlier in the command. In this case, the error is most likely from pwd outputting a path with a space in it. Everything after the space is no longer a parameter to -v and docker tries to parse it as the image name. The fix is to quote the volume parameters when you cannot guarantee it is free of spaces or other special characters.

When you do that, you'll encounter the next error, "executable not found". Everything after the image name is parsed as the command to run inside the container. In your case, it will try to run the command --rm -it bash which will almost certainly fail since --rm will no exist as a binary inside your image. You need to reorder the parameters to resolve that:

 docker run --rm -it -p 8888:8888 -v "`pwd`/../src:/src" -v "`pwd`/../data:/data" -w /src supervisely_anpr  bash

I've got some more details on these two errors and causes in my slides here: https://sudo-bmitch.github.io/presentations/dc2018/faq-stackoverflow-lightning.html#29

How to add a ListView to a Column in Flutter?

Try using Slivers:

Container(
    child: CustomScrollView(
      slivers: <Widget>[
        SliverList(
          delegate: SliverChildListDelegate(
            [
              HeaderWidget("Header 1"),
              HeaderWidget("Header 2"),
              HeaderWidget("Header 3"),
              HeaderWidget("Header 4"),
            ],
          ),
        ),
        SliverList(
          delegate: SliverChildListDelegate(
            [
              BodyWidget(Colors.blue),
              BodyWidget(Colors.red),
              BodyWidget(Colors.green),
              BodyWidget(Colors.orange),
              BodyWidget(Colors.blue),
              BodyWidget(Colors.red),
            ],
          ),
        ),
        SliverGrid(
          gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 2),
          delegate: SliverChildListDelegate(
            [
              BodyWidget(Colors.blue),
              BodyWidget(Colors.green),
              BodyWidget(Colors.yellow),
              BodyWidget(Colors.orange),
              BodyWidget(Colors.blue),
              BodyWidget(Colors.red),
            ],
          ),
        ),
      ],
    ),
  ),
)

Angular 4 - Observable catch error

With angular 6 and rxjs 6 Observable.throw(), Observable.off() has been deprecated instead you need to use throwError

ex :

return this.http.get('yoururl')
  .pipe(
    map(response => response.json()),
    catchError((e: any) =>{
      //do your processing here
      return throwError(e);
    }),
  );

Yarn install command error No such file or directory: 'install'

I had the same issue on Ubuntu 17.04.

This solution worked for me:

sudo apt remove cmdtest
sudo apt remove yarn
curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -
echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list
sudo apt-get update
sudo apt-get install yarn -y

then

yarn install

result:

yarn install v1.3.2
warning You are using Node "6.0.0" which is not supported and may encounter bugs or unexpected behaviour. Yarn supports the following server range: "^4.8.0 || ^5.7.0 || ^6.2.2 || >=8.0.0"
info No lockfile found.
[1/4] Resolving packages...
[2/4] Fetching packages...
[3/4] Linking dependencies...
[4/4] Building fresh packages...

info Lockfile not saved, no dependencies.
Done in 0.20s.

Hope that it will help you.

npm install Error: rollbackFailedOptional

Solution: The default value of ‘proxy’ and ‘https-proxy’ key of npm config is NULL. After doing some more R & D then I tried to set the proxy setting value to above key (this solution works in my scenario).

Also, the same proxy settings need to be applied in IE browser Internet Settings >> Settings >> LAN settings.

Conclusion: In corporate/some environment the proxy is a somewhat mandatory setting otherwise npm install will not work.

Issue on GitHub: https://github.com/SharePoint/sp-dev-docs/issues/3266

You can refer blog for detailed information https://blogs2share.blogspot.com/2019/01/spfx-environment-setup-error.html

How to fix: fatal error: openssl/opensslv.h: No such file or directory in RedHat 7

To fix this problem, you have to install OpenSSL development package, which is available in standard repositories of all modern Linux distributions.

To install OpenSSL development package on Debian, Ubuntu or their derivatives:

$ sudo apt-get install libssl-dev

To install OpenSSL development package on Fedora, CentOS or RHEL:

$ sudo yum install openssl-devel 

Edit : As @isapir has pointed out, for Fedora version>=22 use the DNF package manager :

dnf install openssl-devel

Property 'json' does not exist on type 'Object'

UPDATE: for rxjs > v5.5

As mentioned in some of the comments and other answers, by default the HttpClient deserializes the content of a response into an object. Some of its methods allow passing a generic type argument in order to duck-type the result. Thats why there is no json() method anymore.

import {throwError} from 'rxjs';
import {catchError, map} from 'rxjs/operators';

export interface Order {
  // Properties
}

interface ResponseOrders {
  results: Order[];
}

@Injectable()
export class FooService {
 ctor(private http: HttpClient){}

 fetch(startIndex: number, limit: number): Observable<Order[]> {
    let params = new HttpParams();
    params = params.set('startIndex',startIndex.toString()).set('limit',limit.toString());
    // base URL should not have ? in it at the en
    return this.http.get<ResponseOrders >(this.baseUrl,{
       params
    }).pipe(
       map(res => res.results || []),
       catchError(error => _throwError(error.message || error))
    );
} 

Notice that you could easily transform the returned Observable to a Promise by simply invoking toPromise().

ORIGINAL ANSWER:

In your case, you can

Assumming that your backend returns something like:

{results: [{},{}]}

in JSON format, where every {} is a serialized object, you would need the following:

// Somewhere in your src folder

export interface Order {
  // Properties
}

import { HttpClient, HttpParams } from '@angular/common/http';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/catch';
import 'rxjs/add/operator/map';

import { Order } from 'somewhere_in_src';    

@Injectable()
export class FooService {
 ctor(private http: HttpClient){}

 fetch(startIndex: number, limit: number): Observable<Order[]> {
    let params = new HttpParams();
    params = params.set('startIndex',startIndex.toString()).set('limit',limit.toString());
    // base URL should not have ? in it at the en
    return this.http.get(this.baseUrl,{
       params
    })
    .map(res => res.results as Order[] || []); 
   // in case that the property results in the res POJO doesnt exist (res.results returns null) then return empty array ([])
  }
} 

I removed the catch section, as this could be archived through a HTTP interceptor. Check the docs. As example:

https://gist.github.com/jotatoledo/765c7f6d8a755613cafca97e83313b90

And to consume you just need to call it like:

// In some component for example
this.fooService.fetch(...).subscribe(data => ...); // data is Order[]

Angular 4 setting selected option in Dropdown

Remove [selected] from option tag:

<option *ngFor="let opt of question.options" [value]="opt.key">
  {{opt.selected+opt.value}}
</option>

And in your form builder add:

key: this.question.options.filter(val => val.selected === true).map(data => data.key)

How to get param from url in angular 4?

constructor(private activatedRoute: ActivatedRoute) {
}

ngOnInit() {
    this.activatedRoute.params.subscribe(paramsId => {
        this.id = paramsId.id;
        console.log(this.id);
    });
  
 }

PHP Parse error: syntax error, unexpected '?' in helpers.php 233

I had the same problem with the laravel initiation. The solution was as follows.

1st - I checked the version of my PHP. That it was 5.6 would soon give problem with the laravel.

2nd - I changed the version of my PHP to PHP 7.1.1. ATTENTION, in my case I changed my environment variable that was getting Xampp's PHP version 5.6 I changed to 7.1.1 for laragon.

3rd - I went to the terminal / console and navigated to my folder where my project was and typed the following command: php artisan serves. And it worked! In my case it started at the port: 8000 see example below.

C: \ laragon \ www \ first> php artisan serves Laravel development server started: http://127.0.0.1:8000

I hope I helped someone who has been through the same problem as me.

How to specify credentials when connecting to boto3 S3?

There are numerous ways to store credentials while still using boto3.resource(). I'm using the AWS CLI method myself. It works perfectly.

https://boto3.amazonaws.com/v1/documentation/api/latest/guide/configuration.html?fbclid=IwAR2LlrS4O2gYH6xAF4QDVIH2Q2tzfF_VZ6loM3XfXsPAOR4qA-pX_qAILys

Access Control Origin Header error using Axios in React Web throwing error in Chrome

As I understand the problem is that request is sent from localhost:3000 to localhost:8080 and browser rejects such requests as CORS. So solution was to create proxy

My solution was :

import proxy from 'http-proxy-middleware'
app.use('/api/**', proxy({ target: "http://localhost:8080" }));

webpack: Module not found: Error: Can't resolve (with relative path)

Look the path for example this import is not correct import Navbar from '@/components/Navbar.vue' should look like this ** import Navbar from './components/Navbar.vue'**

pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available

I'm using Windows 10 and installed Miniconda 3 with Python 3.7.

I solved this error by following this https://github.com/conda/conda/issues/8273

Specifically, I copied the following files from C:\Users\MyUser\Miniconda3\Library\bin to C:\Users\MyUser\Miniconda3\DLLs:

  • libcrypto-1_1-x64.dll
  • libcrypto-1_1-x64.pdb
  • libssl-1_1-x64.dll
  • libssl-1_1-x64.pdb

How to create Toast in Flutter?

I would like to provide alternative solution to use package flushbar. https://github.com/AndreHaueisen/flushbar
As the package said: Use this package if you need more customization when notifying your user. For Android developers, it is made to substitute toasts and snackbars.
Another suggestion to use flushbar How to show snackbar after navigator.pop(context) in Flutter?
You can also set flushbarPosition to TOP or BOTTOM
enter image description here

    Flushbar(
      title: "Hey Ninja",
      message: "Lorem Ipsum is simply dummy text of the printing and typesetting industry",
      flushbarPosition: FlushbarPosition.TOP,
      flushbarStyle: FlushbarStyle.FLOATING,
      reverseAnimationCurve: Curves.decelerate,
      forwardAnimationCurve: Curves.elasticOut,
      backgroundColor: Colors.red,
      boxShadows: [BoxShadow(color: Colors.blue[800], offset: Offset(0.0, 2.0), blurRadius: 3.0)],
      backgroundGradient: LinearGradient(colors: [Colors.blueGrey, Colors.black]),
      isDismissible: false,
      duration: Duration(seconds: 4),
      icon: Icon(
        Icons.check,
        color: Colors.greenAccent,
      ),
      mainButton: FlatButton(
        onPressed: () {},
        child: Text(
          "CLAP",
          style: TextStyle(color: Colors.amber),
        ),
      ),
      showProgressIndicator: true,
      progressIndicatorBackgroundColor: Colors.blueGrey,
      titleText: Text(
        "Hello Hero",
        style: TextStyle(
            fontWeight: FontWeight.bold, fontSize: 20.0, color: Colors.yellow[600], fontFamily: "ShadowsIntoLightTwo"),
      ),
      messageText: Text(
        "You killed that giant monster in the city. Congratulations!",
        style: TextStyle(fontSize: 18.0, color: Colors.green, fontFamily: "ShadowsIntoLightTwo"),
      ),
    )..show(context);

Android 8: Cleartext HTTP traffic not permitted

After changed API version 9.0 getting the error Cleartext HTTP traffic to YOUR-API.DOMAIN.COM not permitted (targetSdkVersion="28"). in xamarin, xamarin.android and android studio.

Two steps to solve this error in xamarin, xamarin.android and android studio.

Step 1: Create file resources/xml/network_security_config.xml

In network_security_config.xml

<?xml version="1.0" encoding="utf-8" ?>
<network-security-config>
  <domain-config cleartextTrafficPermitted="true">
    <domain includeSubdomains="true">mobapi.3detrack.in</domain>
  </domain-config>
</network-security-config>

Step 2: update AndroidManifest.xml -

Add android:networkSecurityConfig="@xml/network_security_config" on application tag. e.g:

<application android:label="your App Name" android:icon="@drawable/icon" android:networkSecurityConfig="@xml/network_security_config">

How to calculate 1st and 3rd quartiles?

You can use np.percentile to calculate quartiles (including the median):

>>> np.percentile(df.time_diff, 25)  # Q1
0.48333300000000001

>>> np.percentile(df.time_diff, 50)  # median
0.5

>>> np.percentile(df.time_diff, 75)  # Q3
0.51666699999999999

Or all at once:

>>> np.percentile(df.time_diff, [25, 50, 75])
array([ 0.483333,  0.5     ,  0.516667])

VSCode cannot find module '@angular/core' or any other modules

If you did what I (foolishly) did... Which was drag and drop a component folder into my project then you'll probably be able to solve it by doing what I did to fix it.

Explanation: Basically, by some means Angualar CLI must tell InteliJ what @angular means. If you just plop the file in your project without using the Angular CLI i.e. ng g componentName --module=app.module then Angular CLI doesn't know to update this reference so IntelliJ has no idea what it is.

Approach: Trigger the Angular CLI to update references of @angular. I currently know only one way to do this...

Implementation: Add a new component at the same level as the component your having issues with. ng g tempComponent --module=app.module This should force the Angular CLI to run and update these references in the project. Now just delete the tempComponent you just created and don't forget to remove any reference to it in app.module.

Hope this helps someone else out.

React Router Pass Param to Component

I used this to access the ID in my component:

<Route path="/details/:id" component={DetailsPage}/>

And in the detail component:

export default class DetailsPage extends Component {
  render() {
    return(
      <div>
        <h2>{this.props.match.params.id}</h2>
      </div>
    )
  }
}

This will render any ID inside an h2, hope that helps someone.

npm ERR! code UNABLE_TO_GET_ISSUER_CERT_LOCALLY

The below code worked for me perfectly here make http only instead https

npm config set registry http://registry.npmjs.org/  

How to use img src in vue.js?

Try this:

<img v-bind:src="'/media/avatars/' + joke.avatar" /> 

Don't forget single quote around your path string. also in your data check you have correctly defined image variable.

joke: {
  avatar: 'image.jpg'
}

A working demo here: http://jsbin.com/pivecunode/1/edit?html,js,output

Only on Firefox "Loading failed for the <script> with source"

I've just had the same issue - for me Privacy Badger on Firefox was the issue - not adblocker. Posting for posterity

Docker - Bind for 0.0.0.0:4000 failed: port is already allocated

docker ps will reveal the list of containers running on docker. Find the one running on your needed port and note down its PID.

Stop and remove that container using following commands:

docker stop PID
docker rm PID

Now run docker-compose up and your services should run as you have freed the needed port.

Error: More than one module matches. Use skip-import option to skip importing the component into the closest module

When there is more than one module under app folder, generating a component with below command will fail:

ng generate component New-Component-Name

The reason is angular CLI detects multiple module, and does't know in which module to add the component. So, you need to explicitly mention which module component will be added:

ng generate component New-Component-Name --module=ModuleName

How to use log4net in Asp.net core 2.0

Still looking for a solution? I got mine from this link .

All I had to do was add this two lines of code at the top of "public static void Main" method in the "program class".

 var logRepo = LogManager.GetRepository(Assembly.GetEntryAssembly());
 XmlConfigurator.Configure(logRepo, new FileInfo("log4net.config"));

Yes, you have to add:

  1. Microsoft.Extensions.Logging.Log4Net.AspNetCore using NuGet.
  2. A text file with the name of log4net.config and change the property(Copy to Output Directory) of the file to "Copy if Newer" or "Copy always".

You can also configure your asp.net core application in such a way that everything that is logged in the output console will be logged in the appender of your choice. You can also download this example code from github and see how i configured it.

ReactJS - .JS vs .JSX

JSX tags (<Component/>) are clearly not standard javascript and have no special meaning if you put them inside a naked <script> tag for example. Hence all React files that contain them are JSX and not JS.

By convention, the entry point of a React application is usually .js instead of .jsx even though it contains React components. It could as well be .jsx. Any other JSX files usually have the .jsx extension.

In any case, the reason there is ambiguity is because ultimately the extension does not matter much since the transpiler happily munches any kinds of files as long as they are actually JSX.

My advice would be: don't worry about it.

How do you set the document title in React?

You can use the following below with document.title = 'Home Page'

import React from 'react'
import { Component } from 'react-dom'


class App extends Component{
  componentDidMount(){
    document.title = "Home Page"
  }

  render(){
    return(
      <p> Title is now equal to Home Page </p>
    )
  }
}

ReactDOM.render(
  <App />,
  document.getElementById('root')
);

or You can use this npm package npm i react-document-title

import React from 'react'
import { Component } from 'react-dom'
import DocumentTitle from 'react-document-title';


class App extends Component{


  render(){
    return(
      <DocumentTitle title='Home'>
        <h1>Home, sweet home.</h1>
      </DocumentTitle>
    )
  }
}

ReactDOM.render(
  <App />,
  document.getElementById('root')
);

Happy Coding!!!

laravel 5.5 The page has expired due to inactivity. Please refresh and try again

if you need to change form action with Javascript you will have the same problem

1.first you need to use instead of {!!Form::open() !!} {!! close() !!} in laravel
2.second you most begin your action with https://www.example.com +your Route

Do not Forget www in your url!!!

"The page has expired due to inactivity" - Laravel 5.5

Be sure to have the correct system time on your web server. In my case, the vagrant machine was in the future (Jan 26 14:08:26 UTC 2226) so of course the time in my browser's session cookie had expired some 200+ years ago.

Converting unix time into date-time via excel

in case the above does not work for you. for me this did not for some reasons;

the UNIX numbers i am working on are from the Mozilla place.sqlite dates.

to make it work : i splitted the UNIX cells into two cells : one of the first 10 numbers (the date) and the other 4 numbers left (the seconds i believe)

Then i used this formula, =(A1/86400)+25569 where A1 contains the cell with the first 10 number; and it worked

Restart container within pod

Is it possible to restart a single container

Not through kubectl, although depending on the setup of your cluster you can "cheat" and docker kill the-sha-goes-here, which will cause kubelet to restart the "failed" container (assuming, of course, the restart policy for the Pod says that is what it should do)

how do I restart the pod

That depends on how the Pod was created, but based on the Pod name you provided, it appears to be under the oversight of a ReplicaSet, so you can just kubectl delete pod test-1495806908-xn5jn and kubernetes will create a new one in its place (the new Pod will have a different name, so do not expect kubectl get pods to return test-1495806908-xn5jn ever again)

Display/Print one column from a DataFrame of Series in Pandas

Not sure what you are really after but if you want to print exactly what you have you can do:

Option 1

print(df['Item'].to_csv(index=False))

Sweet
Candy
Chocolate

Option 2

for v in df['Item']:
    print(v)

Sweet
Candy
Chocolate

ModuleNotFoundError: No module named 'sklearn'

install these ==>> pip install -U scikit-learn scipy matplotlib if still getting the same error then , make sure that your imoprted statment should be correct. i made the mistike while writing ensemble so ,(check spelling) its should be >>> from sklearn.ensemble import RandomForestClassifier

Vuex - Computed property "name" was assigned to but it has no setter

I was facing exact same error

Computed property "callRingtatus" was assigned to but it has no setter

here is a sample code according to my scenario

computed: {

callRingtatus(){
            return this.$store.getters['chat/callState']===2
      }

}

I change the above code into the following way

computed: {

callRingtatus(){
       return this.$store.state.chat.callState===2
    }
}

fetch values from vuex store state instead of getters inside the computed hook

Vuex - passing multiple parameters to mutation

Mutations expect two arguments: state and payload, where the current state of the store is passed by Vuex itself as the first argument and the second argument holds any parameters you need to pass.

The easiest way to pass a number of parameters is to destruct them:

mutations: {
    authenticate(state, { token, expiration }) {
        localStorage.setItem('token', token);
        localStorage.setItem('expiration', expiration);
    }
}

Then later on in your actions you can simply

store.commit('authenticate', {
    token,
    expiration,
});

How to increment a letter N times per iteration and store in an array?

Here is your solution for the problem,

$letter = array();
for ($i = 'A'; $i !== 'ZZ'; $i++){
        if(ord($i) % 2 != 0)
           $letter[] .= $i;
}
print_r($letter);

You need to get the ASCII value for that character which will solve your problem.

Here is ord doc and working code.

For your requirement, you can do like this,

for ($i = 'A'; $i !== 'ZZ'; ord($i)+$x){
  $letter[] .= $i;
}
print_r($letter);

Here set $x as per your requirement.

How to check which version of Keras is installed?

The simplest way is using pip command:

pip list | grep Keras

No converter found capable of converting from type to type

If you look at the exception stack trace it says that, it failed to convert from ABDeadlineType to DeadlineType. Because your repository is going to return you the objects of ABDeadlineType. How the spring-data-jpa will convert into the other one(DeadlineType). You should return the same type from repository and then have some intermediate util class to convert it into your model class.

public interface ABDeadlineTypeRepository extends JpaRepository<ABDeadlineType, Long> {
    List<ABDeadlineType> findAllSummarizedBy();
}

How to VueJS router-link active style

https://router.vuejs.org/en/api/router-link.html add attribute active-class="active" eg:

<ul class="nav navbar-nav">
    <router-link tag="li" active-class="active" to="/" exact><a>Home</a></router-link>
    <router-link tag="li" active-class="active" to="/about"><a>About</a></router-link>
    <router-link tag="li" active-class="active" to="/permission-list"><a>Permisison</a></router-link>
</ul>

Subtracting 1 day from a timestamp date

Use the INTERVAL type to it. E.g:

--yesterday
SELECT NOW() - INTERVAL '1 DAY';

--Unrelated to the question, but PostgreSQL also supports some shortcuts:
SELECT 'yesterday'::TIMESTAMP, 'tomorrow'::TIMESTAMP, 'allballs'::TIME;

Then you can do the following on your query:

SELECT 
    org_id,
    count(accounts) AS COUNT,
    ((date_at) - INTERVAL '1 DAY') AS dateat
FROM 
    sourcetable
WHERE 
    date_at <= now() - INTERVAL '130 DAYS'
GROUP BY 
    org_id,
    dateat;


TIPS

Tip 1

You can append multiple operands. E.g.: how to get last day of current month?

SELECT date_trunc('MONTH', CURRENT_DATE) + INTERVAL '1 MONTH - 1 DAY';

Tip 2

You can also create an interval using make_interval function, useful when you need to create it at runtime (not using literals):

SELECT make_interval(days => 10 + 2);
SELECT make_interval(days => 1, hours => 2);
SELECT make_interval(0, 1, 0, 5, 0, 0, 0.0);


More info:

Date/Time Functions and Operators

datatype-datetime (Especial values).

Can't install laravel installer via composer

For PHP7.1 install this

sudo apt-get install php7.1-zip

npm WARN ... requires a peer of ... but none is installed. You must install peer dependencies yourself

The accepted answer of using npm-install-peers did not work, nor removing node_modules and rebuilding. The answer to run

npm install --save-dev @xxxxx/xxxxx@latest

for each one, with the xxxxx referring to the exact text in the peer warning, worked. I only had four warnings, if I had a dozen or more as in the question, it might be a good idea to script the commands.

How to Update a Component without refreshing full page - Angular

Angular will automatically update a component when it detects a variable change .

So all you have to do for it to "refresh" is ensure that the header has a reference to the new data. This could be via a subscription within header.component.ts or via an @Input variable...


an example...

main.html

<app-header [header-data]="headerData"></app-header>

main.component.ts

public headerData:int = 0;

ngOnInit(){
    setInterval(()=>{this.headerData++;}, 250);
}

header.html

<p>{{data}}</p>

header.ts

@Input('header-data') data;

In the above example, the header will recieve the new data every 250ms and thus update the component.


For more information about Angular's lifecycle hooks, see: https://angular.io/guide/lifecycle-hooks

PYODBC--Data source name not found and no default driver specified

Try below:

import pyodbc

server = 'servername'

database = 'DB'

username = 'UserName'

password = 'Password'

cnxn = pyodbc.connect('DRIVER={ODBC Driver 13 for SQL Server};SERVER='+server+';DATABASE='+database+';UID='+username+';PWD='+ password)

cursor = cnxn.cursor()


cursor.execute('SELECT * FROM Tbl')

for row in cursor:
    print('row = %r' % (row,))

How to test the type of a thrown exception in Jest

I haven't tried it myself, but I would suggest using Jest's toThrow assertion. So I guess your example would look something like this:

it('should throw Error with message \'UNKNOWN ERROR\' when no parameters were passed', (t) => {
  const error = t.throws(() => {
    throwError();
  }, TypeError);

  expect(t).toThrowError('UNKNOWN ERROR');
  //or
  expect(t).toThrowError(TypeError);
});

Again, I haven't test it, but I think it should work.

exporting multiple modules in react.js

You can have only one default export which you declare like:

export default App; or export default class App extends React.Component {...

and later do import App from './App'

If you want to export something more you can use named exports which you declare without default keyword like:

export {
  About,
  Contact,
}

or:

export About;
export Contact;

or:

export const About = class About extends React.Component {....
export const Contact = () => (<div> ... </div>);

and later you import them like:

import App, { About, Contact } from './App';

EDIT:

There is a mistake in the tutorial as it is not possible to make 3 default exports in the same main.js file. Other than that why export anything if it is no used outside the file?. Correct main.js :

import React from 'react';
import ReactDOM from 'react-dom';
import { Router, Route, Link, browserHistory, IndexRoute  } from 'react-router'

class App extends React.Component {
...
}

class Home extends React.Component {
...
}


class About extends React.Component {
...
}


class Contact extends React.Component {
...
}


ReactDOM.render((
   <Router history = {browserHistory}>
      <Route path = "/" component = {App}>
         <IndexRoute component = {Home} />
         <Route path = "home" component = {Home} />
         <Route path = "about" component = {About} />
         <Route path = "contact" component = {Contact} />
      </Route>
   </Router>

), document.getElementById('app'))

EDIT2:

another thing is that this tutorial is based on react-router-V3 which has different api than v4.

Bootstrap 4 Dropdown Menu not working?

I used NuGet to install BootStrap 4. I was also having issues with it not displaying the Dropdown on click. It kept throwing an error in jquery base on what the Chrome console was telling me.

I originally had the following

<%-- CSS --%>
<link type="text/css" rel="stylesheet" href="/Content/bootstrap.css" />

 <%-- JS --%>
<script type="text/javascript" src="/Scripts/jquery-3.3.1.min.js"></script>
<script type="text/javascript" src="/Scripts/bootstrap.min.js"></script>

But I changed it to use the bundled version instead and it started to work

<%-- CSS --%>
<link type="text/css" rel="stylesheet" href="/Content/bootstrap.css" />

<%-- JS --%>
<script type="text/javascript" src="/Scripts/jquery-3.3.1.min.js"></script>
<script type="text/javascript" src="/Scripts/bootstrap.bundle.min.js"></script>

Get first line of a shell command's output

Yes, that is one way to get the first line of output from a command.

If the command outputs anything to standard error that you would like to capture in the same manner, you need to redirect the standard error of the command to the standard output stream:

utility 2>&1 | head -n 1

There are many other ways to capture the first line too, including sed 1q (quit after first line), sed -n 1p (only print first line, but read everything), awk 'FNR == 1' (only print first line, but again, read everything) etc.

Catching errors in Angular HttpClient

import { Observable, throwError } from 'rxjs';
import { catchError } from 'rxjs/operators';

const PASSENGER_API = 'api/passengers';

getPassengers(): Observable<Passenger[]> {
  return this.http
    .get<Passenger[]>(PASSENGER_API)
    .pipe(catchError((error: HttpErrorResponse) => throwError(error)));
}

How do I use Safe Area Layout programmatically?

Safe area extension For Objective-C

@implementation UIView (SafeArea)

- (NSLayoutAnchor *)safeTopAnchor{

    if (@available(iOS 11.0, *)){
        return self.safeAreaLayoutGuide.topAnchor;
    } else {
        return self.topAnchor;
    }

}


- (NSLayoutAnchor *)safeBottomAnchor{

    if (@available(iOS 11.0, *)) {
        return self.safeAreaLayoutGuide.bottomAnchor;
    } else {
        return self.bottomAnchor;
    }

}

@end

Fixing Xcode 9 issue: "iPhone is busy: Preparing debugger support for iPhone"

The 'Continue' button is under the error message. Just hit 'Enter'

You should confirm that the device was listed on my 'Managed Devices' on Apple @ https://appleid.apple.com/account/manage

iPhone X / 8 / 8 Plus CSS media queries

I noticed that the answers here are using: device-width, device-height, min-device-width, min-device-height, max-device-width, max-device-height.

Please refrain from using them since they are deprecated. see MDN for reference. Instead use the regular min-width, max-width and so on. For extra assurance, you can set the min and max to the same px amount. For example:

iPhone X

@media only screen 
    and (width : 375px) 
    and (height : 635px)
    and (orientation : portrait)  
    and (-webkit-device-pixel-ratio : 3) { }

You may also notice that I am using 635px for height. Try it yourself the window height is actually 635px. run iOS simulator for iPhone X and in Safari Web inspector do window.innerHeight. Here are a few useful links on this subject:

How to view Plugin Manager in Notepad++

I changed the plugin folder name. Restart Notepad ++ It works now, a

Set cookies for cross origin requests

Note for Chrome Browser released in 2020.

A future release of Chrome will only deliver cookies with cross-site requests if they are set with SameSite=None and Secure.

So if your backend server does not set SameSite=None, Chrome will use SameSite=Lax by default and will not use this cookie with { withCredentials: true } requests.

More info https://www.chromium.org/updates/same-site.

Firefox and Edge developers also want to release this feature in the future.

Spec found here: https://tools.ietf.org/html/draft-west-cookie-incrementalism-01#page-8

intellij idea - Error: java: invalid source release 1.9

In Project Structure in Project SDK: modify SDK to 11 or higher and in Project language level: modify to 11 - Local variable syntax for lambda parameters

XMLHttpRequest blocked by CORS Policy

I believe sideshowbarker 's answer here has all the info you need to fix this. If your problem is just No 'Access-Control-Allow-Origin' header is present on the response you're getting, you can set up a CORS proxy to get around this. Way more info on it in the linked answer

Cannot open new Jupyter Notebook [Permission Denied]

change the ownership of the ~/.local/share/jupyter directory from root to user.

sudo chown -R user:user ~/.local/share/jupyter 

see here: https://github.com/ipython/ipython/issues/8997

The first user before the colon is your username, the second user after the colon is your group. If you get chown: [user]: illegal group name, find your group with groups, or specify no group with sudo chown user: ~/.local/share/jupyter.

EDIT: Added -R option in comments to the answer. You have to change ownership of all files inside this directory (or inside ~/.jupyter/, wherever it gives you PermissionError) to your user to make it work.

Unable to merge dex

With Android Studio 3.0 stable build Below steps worked for me:

  1. Got to SdkManager-->Android Sdk --> Sdk Tools and Update Google play services to latest version to 46.
  2. Clean project and rebuild project.

Change arrow colors in Bootstraps carousel

To customize the colors for the carousel controls, captions, and indicators using Sass you can include these variables

    $carousel-control-color: 
    $carousel-caption-color: 
    $carousel-indicator-active-bg: 

React - How to force a function component to render?

I used a third party library called use-force-update to force render my react functional components. Worked like charm. Just use import the package in your project and use like this.

import useForceUpdate from 'use-force-update';

const MyButton = () => {

  const forceUpdate = useForceUpdate();

  const handleClick = () => {
    alert('I will re-render now.');
    forceUpdate();
  };

  return <button onClick={handleClick} />;
};

How to add an item to an ArrayList in Kotlin?

If you have a MUTABLE collection:

val list = mutableListOf(1, 2, 3)
list += 4

If you have an IMMUTABLE collection:

var list = listOf(1, 2, 3)
list += 4

note that I use val for the mutable list to emphasize that the object is always the same, but its content changes.

In case of the immutable list, you have to make it var. A new object is created by the += operator with the additional value.

git clone error: RPC failed; curl 56 OpenSSL SSL_read: SSL_ERROR_SYSCALL, errno 10054

I had the same issue, and I have solved it by changing my net connection. In fact, my last internet connection was too slow (45 kbit/s). So you should try again with a faster net connection.

Cordova app not displaying correctly on iPhone X (Simulator)

For a manual fix to an existing cordova project

The black bars

Add this to your info.plist file. Fixing the launch image is a separate issue i.e. How to Add iPhoneX Launch Image

<key>UILaunchStoryboardName</key>
<string>CDVLaunchScreen</string>

The white bars

Set viewport-fit=cover in the meta tag

<meta name="viewport" content="initial-scale=1, width=device-width, height=device-height, viewport-fit=cover">

Iterate over array of objects in Typescript

In Typescript and ES6 you can also use for..of:

for (var product of products) {
     console.log(product.product_desc)
}

which will be transcoded to javascript:

for (var _i = 0, products_1 = products; _i < products_1.length; _i++) {
    var product = products_1[_i];
    console.log(product.product_desc);
}

ImportError: Couldn't import Django

windows :

  1. (virtualenv dir)\Scripts\activate # this step to activate virtualenv

  2. you should be in the dir of (project name)

  3. python manage.py runserver

Detect if the device is iPhone X

After looking at all the answers this is what I ended up doing:

Solution (Swift 4.1 compatible)

extension UIDevice {
    static var isIphoneX: Bool {
        var modelIdentifier = ""
        if isSimulator {
            modelIdentifier = ProcessInfo.processInfo.environment["SIMULATOR_MODEL_IDENTIFIER"] ?? ""
        } else {
            var size = 0
            sysctlbyname("hw.machine", nil, &size, nil, 0)
            var machine = [CChar](repeating: 0, count: size)
            sysctlbyname("hw.machine", &machine, &size, nil, 0)
            modelIdentifier = String(cString: machine)
        }

        return modelIdentifier == "iPhone10,3" || modelIdentifier == "iPhone10,6"
    }

    static var isSimulator: Bool {
        return TARGET_OS_SIMULATOR != 0
    }
}

Use

if UIDevice.isIphoneX {
    // is iPhoneX
} else {
    // is not iPhoneX
}

Note

Pre Swift 4.1 you can check if the app is running on a simulator like so:

TARGET_OS_SIMULATOR != 0

From Swift 4.1 and onwards you can check if the app is running on a simulator using the Target environment platform condition:

#if targetEnvironment(simulator)
    return true
#else
    return false
#endif

(the older method will still work, but this new method is more future proof)

Extract a page from a pdf as a jpeg

Here is a solution which requires no additional libraries and is very fast. This was found from: https://nedbatchelder.com/blog/200712/extracting_jpgs_from_pdfs.html# I have added the code in a function to make it more convenient.

def convert(filepath):
    with open(filepath, "rb") as file:
        pdf = file.read()

    startmark = b"\xff\xd8"
    startfix = 0
    endmark = b"\xff\xd9"
    endfix = 2
    i = 0

    njpg = 0
    while True:
        istream = pdf.find(b"stream", i)
        if istream < 0:
            break
        istart = pdf.find(startmark, istream, istream + 20)
        if istart < 0:
            i = istream + 20
            continue
        iend = pdf.find(b"endstream", istart)
        if iend < 0:
            raise Exception("Didn't find end of stream!")
        iend = pdf.find(endmark, iend - 20)
        if iend < 0:
            raise Exception("Didn't find end of JPG!")

        istart += startfix
        iend += endfix
        jpg = pdf[istart:iend]
        newfile = "{}jpg".format(filepath[:-3])
        with open(newfile, "wb") as jpgfile:
            jpgfile.write(jpg)

        njpg += 1
        i = iend

        return newfile

Call convert with the pdf path as the argument and the function will create a .jpg file in the same directory

HTTP Request in Kotlin

GET and POST using OkHttp

private const val CONNECT_TIMEOUT = 15L
private const val READ_TIMEOUT = 15L
private const val WRITE_TIMEOUT = 15L

private fun performPostOperation(urlString: String, jsonString: String, token: String): String? {
    return try {
        val client = OkHttpClient.Builder()
            .connectTimeout(CONNECT_TIMEOUT, TimeUnit.SECONDS)
            .writeTimeout(WRITE_TIMEOUT, TimeUnit.SECONDS)
            .readTimeout(READ_TIMEOUT, TimeUnit.SECONDS)
            .build()

        val body = jsonString.toRequestBody("application/json; charset=utf-8".toMediaTypeOrNull())

        val request = Request.Builder()
            .url(URL(urlString))
            .header("Authorization", token)
            .post(body)
            .build()

        val response = client.newCall(request).execute()
        response.body?.string()
    }
    catch (e: IOException) {
        e.printStackTrace()
        null
    }
}

private fun performGetOperation(urlString: String, token: String): String? {
    return try {
        val client = OkHttpClient.Builder()
            .connectTimeout(CONNECT_TIMEOUT, TimeUnit.SECONDS)
            .writeTimeout(WRITE_TIMEOUT, TimeUnit.SECONDS)
            .readTimeout(READ_TIMEOUT, TimeUnit.SECONDS)
            .build()

        val request = Request.Builder()
            .url(URL(urlString))
            .header("Authorization", token)
            .get()
            .build()

        val response = client.newCall(request).execute()
        response.body?.string()
    }
    catch (e: IOException) {
        e.printStackTrace()
        null
    }
}

Object serialization and deserialization

@Throws(JsonProcessingException::class)
fun objectToJson(obj: Any): String {
    return ObjectMapper().writeValueAsString(obj)
}

@Throws(IOException::class)
fun jsonToAgentObject(json: String?): MyObject? {
    return if (json == null) { null } else {
        ObjectMapper().readValue<MyObject>(json, MyObject::class.java)
    }
}

Dependencies

Put the following lines in your gradle (app) file. Jackson is optional. You can use it for object serialization and deserialization.

implementation 'com.squareup.okhttp3:okhttp:4.3.1'
implementation 'com.fasterxml.jackson.core:jackson-core:2.9.8'
implementation 'com.fasterxml.jackson.core:jackson-annotations:2.9.8'
implementation 'com.fasterxml.jackson.core:jackson-databind:2.9.8'

LabelEncoder: TypeError: '>' not supported between instances of 'float' and 'str'

As string data types have variable length, it is by default stored as object type. I faced this problem after treating missing values too. Converting all those columns to type 'category' before label encoding worked in my case.

df[cat]=df[cat].astype('category')

And then check df.dtypes and perform label encoding.

vuetify center items into v-flex

wrap button inside <div class="text-xs-center">

<div class="text-xs-center">
  <v-btn primary>
    Signup
  </v-btn>
</div>

Dev uses it in his examples.


For centering buttons in v-card-actions we can add class="justify-center" (note in v2 class is text-center (so without xs):

<v-card-actions class="justify-center">
  <v-btn>
    Signup
  </v-btn>
</v-card-actions>

Codepen


For more examples with regards to centering see here

Vuejs: Event on route change

If you are using v2.2.0 then there is one more option available to detect changes in $routes.

To react to params changes in the same component, you can watch the $route object:

const User = {
  template: '...',
  watch: {
    '$route' (to, from) {
      // react to route changes...
    }
  }
}

Or, use the beforeRouteUpdate guard introduced in 2.2:

const User = {
  template: '...',
  beforeRouteUpdate (to, from, next) {
    // react to route changes...
    // don't forget to call next()
  }
}

Reference: https://router.vuejs.org/en/essentials/dynamic-matching.html

Failed to install android-sdk: "java.lang.NoClassDefFoundError: javax/xml/bind/annotation/XmlSchema"

I had recently solved this problem by uninstalling the higher version of JDK and installing JDK 8. After installing the JDK you need to give the path. Then you need to open command prompt in "C:\Users\Milan Adhikari\AppData\Local\Android\Sdk\tools" and run "sdkmanager --update" which will update your sdk and then you need to run "flutter doctor --android-licenses" in cmd and accept all the licenses.
Now your problem should be solved.

What is the difference between CSS and SCSS?

Variable definitions right:

$      => SCSS, SASS
--     => CSS
@      => LESS

All answers is good but question a little different than answers

"about Sass. How is SCSS different from CSS" : scss is well formed CSS3 syntax. uses sass preprocessor to create that.

and if I use SCSS instead of CSS will it work the same? yes. if your ide supports sass preprocessor. than it will work same.

Sass has two syntaxes. The most commonly used syntax is known as “SCSS” (for “Sassy CSS”), and is a superset of CSS3’s syntax. This means that every valid CSS3 stylesheet is valid SCSS as well. SCSS files use the extension .scss.

The second, older syntax is known as the indented syntax (or just “.sass”). Inspired by Haml’s terseness, it’s intended for people who prefer conciseness over similarity to CSS. Instead of brackets and semicolons, it uses the indentation of lines to specify blocks. Files in the indented syntax use the extension .sass.


  • Furher Information About:

What Is A CSS Preprocessor?

CSS in itself is devoid of complex logic and functionality which is required to write reusable and organized code. As a result, a developer is bound by limitations and would face extreme difficulty in code maintenance and scalability, especially when working on large projects involving extensive code and multiple CSS stylesheets. This is where CSS Preprocessors come to the rescue.

A CSS Preprocessor is a tool used to extend the basic functionality of default vanilla CSS through its own scripting language. It helps us to use complex logical syntax like – variables, functions, mixins, code nesting, and inheritance to name a few, supercharging your vanilla CSS. By using CSS Preprocessors, you can seamlessly automate menial tasks, build reusable code snippets, avoid code repetition and bloating and write nested code blocks that are well organized and easy to read. However, browsers can only understand native vanilla CSS code and will be unable to interpret the CSS Preprocessor syntax. Therefore, the complex and advanced Preprocessor syntax needs to be first compiled into native CSS syntax which can then be interpreted by the browsers to avoid cross browser compatibility issues. While different Preprocessors have their own unique syntaxes, eventually all of them are compiled to the same native CSS code.

Moving forward in the article, we will take a look at the 3 most popular CSS Preprocessors currently being used by developers around the world i.e Sass, LESS, and Stylus. Before you decide the winner between Sass vs LESS vs Stylus, let us get to know them in detail first.

Sass – Syntactically Awesome Style Sheets

Sass is the acronym for “Syntactically Awesome Style Sheets”. Sass is not only the most popular CSS Preprocessor in the world but also one of the oldest, launched in 2006 by Hampton Catlin and later developed by Natalie Weizenbaum. Although Sass is written in Ruby language, a Precompiler LibSass allows Sass to be parsed in other languages and decouple it from Ruby. Sass has a massive active community and extensive learning resources available on the net for beginners. Thanks to its maturity, stability and powerful logical prowess, Sass has established itself to the forefront of CSS Preprocessor ahead of its rival peers.

Sass can be written in 2 syntaxes either using Sass or SCSS. What is the difference between the two? Let’s find out.

Syntax Declaration: Sass vs SCSS

  • SCSS stands for Sassy CSS. Unlike Sass, SCSS is not based on indentation.
  • .sass extension is used as original syntax for Sass, while SCSS offers a newer syntax with .scss extension.
  • Unlike Sass, SCSS has curly braces and semicolons, just like CSS.
  • Contrary to SCSS, Sass is difficult to read as it is quite deviant from CSS. Which is why SCSS it the more recommended Sass syntax as it is easier to read and closely resembles Native CSS while at the same time enjoying with power of Sass.

Consider the example below with Sass vs SCSS syntax along with Compiled CSS code.

Sass SYNTAX
    $font-color: #fff
    $bg-color: #00f

    #box
      color: $font-color
      background: $bg-color

SCSS SYNTAX
    $font-color: #fff;
    $bg-color: #00f;

    #box{
      color: $font-color;
      background: $bg-color;
    }

In both cases, be it Sass or SCSS, the compiled CSS code will be the same –

#box {
      color: #fff;
      background: #00f;

Usage of Sass

Arguably the most Popular front end framework Bootstrap is written in Sass. Up until version 3, Bootstrap was written in LESS but bootstrap 4 adopted Sass and boosted its popularity. A few of the big companies using Sass are – Zapier, Uber, Airbnb and Kickstarter.

LESS – Leaner Style Sheets

LESS is an acronym for “Leaner Stylesheets”. It was released in 2009 by Alexis Sellier, 3 years after the initial launch of Sass in 2006. While Sass is written in Ruby, LESS is written JavaScript. In fact, LESS is a JavaScript library that extends the functionality of native vanilla CSS with mixins, variables, nesting and rule set loop. Sass vs LESS has been a heated debate. It is no surprise that LESS is the strongest competitor to Sass and has the second-largest user base. However, When bootstrap dumped LESS in favor of Sass with the launch of Bootstrap 4, LESS has waned in popularity. One of the few disadvantages of LESS over Sass is that it does not support functions. Unlike Sass, LESS uses @ to declare variables which might cause confusion with @media and @keyframes. However, One key advantage of LESS over Sass and Stylus or any other preprocessors, is the ease of adding it in your project. You can do that either by using NPM or by incorporating Less.js file. Syntax Declaration: LESS Uses .less extension. Syntax of LESS is quite similar to SCSS with the exception that for declaring variables, instead of $ sign, LESS uses @.

@font-color: #fff;
    @bg-color: #00f

    #box{
      color: @font-color;
      background: @bg-color;
    }

COMPILED CSS
    #box {
        color: #fff;
        background: #00f;
      }

Usage Of LESS The popular Bootstrap framework until the launch of version 4 was written in LESS. However, another popular framework called SEMANTIC UI is still written in LESS. Among the big companies using Sass are – Indiegogo, Patreon, and WeChat

Stylus

The stylus was launched in 2010 by former Node JS developer TJ Holowaychuk, nearly 4 years after the release of Sass and 1 year after the release of LESS. The stylus is written Node JS and fits perfectly with JS stack. The stylus was heavily influenced by the logical prowess of the Sass and simplicity of LESS. Even though Stylus is still popular with Node JS developers, it hasn’t managed to carve out a sizeable share for itself. One advantage of Stylus over Sass or LESS, is that it is armed with extremely powerful built-in functions and is capable of handling heavy computing.

Syntax Declaration: Stylus Uses .styl extension. Stylus offers a great deal of flexibility in writing syntax, supports native CSS as well as allows omission of brackets colons and semicolons. Also, note that Stylus does not use @ or $ symbols for defining variables. Instead, Stylus uses the assignment operators to indicate a variable declaration.

STYLUS SYNTAX WRITTEN LIKE NATIVE CSS

font-color = #fff;
bg-color = #00f;

#box {
    color: font-color;
    background: bg-color;
}

OR

STYLUS SYNTAX WITHOUT CURLY BRACES

font-color = #fff;
bg-color = #00f;

#box 
    color: font-color;
    background: bg-color;

OR

STYLUS SYNTAX WITHOUT COLONS AND SEMICOLONS

font-color = #fff
bg-color = #00f

#box 
    color font-color
    background bg-color

TypeScript error TS1005: ';' expected (II)

The issue was in my code.

In large code base, issue was not clear.

A simplified code is below:

Bad:

 collection.insertMany(
    [[],
    function (err, result) {
    });

Good:

collection.insertMany(
    [],
    function (err, result) {
    });

That is, the first one has [[], instead of normal array []

TS error was not clear enough, and it showed error in the last line with });

Hope this helps.

Pipenv: Command Not Found

I have same problem with pipenv on Mac OS X 10.13 High Seirra, another Mac works just fine. I use Heroku to deploy my Django servers, some in 2.7 and some in 3.6. So, I need both 2.7 and 3.6. When HomeBrew install Python, it keeps python points to original 2.7, and python3 points to 3.6.

The problem might due to $ pip install pipenv. I checked /usr/local/bin and pipenv isn't there. So, I tried a full uninstall:

$ pip uninstall pipenv

Cannot uninstall requirement pipenv, not installed
You are using pip version 9.0.1, however version 10.0.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.

$ pip3 uninstall pipenv
Skipping pipenv as it is not installed.

Then reinstall and works now:

$ pip3 install pipenv
Collecting pipenv

Enable/disable buttons with Angular

Set a property for the current lesson: currentLesson. It will hold, obviously, the 'number' of the choosen lesson. On each button click, set the currentLesson value to 'number'/ order of the button, i.e. for the first button, it will be '1', for the second '2' and so on. Each button now can be disabled with [disabled] attribute, if it the currentLesson is not the same as it's order.

HTML

  <button  (click)="currentLesson = '1'"
         [disabled]="currentLesson !== '1'" class="primair">
           Start lesson</button>
  <button (click)="currentLesson = '2'"
         [disabled]="currentLesson !== '2'" class="primair">
           Start lesson</button>
 .....//so on

Typescript

currentLesson:string;

  classes = [
{
  name: 'string',
  level: 'string',
  code: 'number',
  currentLesson: '1'
}]

constructor(){
  this.currentLesson=this.classes[0].currentLesson
}

DEMO

Putting everything in a loop:

HTML

<div *ngFor="let class of classes; let i = index">
   <button [disabled]="currentLesson !== i + 1" class="primair">
           Start lesson {{i +  1}}</button>
</div>

Typescript

currentLesson:string;

classes = [
{
  name: 'Lesson1',
  level: 1,
  code: 1,
},{
  name: 'Lesson2',
  level: 1,
  code: 2,
},
{
  name: 'Lesson3',
  level: 2,
  code: 3,
}]

DEMO

Node - was compiled against a different Node.js version using NODE_MODULE_VERSION 51

I had the same problem and none of these solutions worked and I don't know why, they worked for me in the past for similar problems.

Anyway to solve the problem I've just manually rebuild the package using node-pre-gyp

cd node_modules/bcrypt
node-pre-gyp rebuild

And everything worked as expected.

Hope this helps

Jupyter notebook not running code. Stuck on In [*]

enter image description here

This is mean your program is still running in background, you need to click shutdown (Shown in attached Image).

*** Shutdown the Running cell and again run your program.

iOS Swift - Get the Current Local Time and Date Timestamp

The simple way to create Current TimeStamp. like below,

func generateCurrentTimeStamp () -> String {
    let formatter = DateFormatter()
    formatter.dateFormat = "yyyy_MM_dd_hh_mm_ss"
    return (formatter.string(from: Date()) as NSString) as String
}

get list of packages installed in Anaconda

in terminal, type : conda list to obtain the packages installed using conda.

for the packages that pip recognizes, type : pip list

There may be some overlap of these lists as pip may recognize packages installed by conda (but maybe not the other way around, IDK).

There is a useful source here, including how to update or upgrade packages..

MongoDB: How To Delete All Records Of A Collection in MongoDB Shell?

Delete all documents from a collection in cmd:

cd C:\Program Files\MongoDB\Server\4.2\bin
mongo
use yourdb
db.yourcollection.remove( { } )

Automatically set appsettings.json for dev and release environments in asp.net core?

In ASP.NET Core you should rather use Environment Variables instead of build configuration for proper appsettings.json

  1. Right click on you project > Properties > Debug > Environment Variables

    environment variables

  2. ASP.NET Core will use the appropriate appsettings.json file:

    example of appsettings files in solution explorer

  3. Now you can use that Environment Variable like this:

    public Startup(IHostingEnvironment env)
    {
        var builder = new ConfigurationBuilder()
            .SetBasePath(env.ContentRootPath)
            .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
            .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
            .AddEnvironmentVariables();
    
        Configuration = builder.Build();
    }
    

Note: If you use @Dmitry's answer, you can run into problems eg. when overriding appsettings.json values on Azure.

How can I convert a char to int in Java?

The ASCII table is arranged so that the value of the character '9' is nine greater than the value of '0'; the value of the character '8' is eight greater than the value of '0'; and so on.

So you can get the int value of a decimal digit char by subtracting '0'.

char x = '9';
int y = x - '0'; // gives the int value 9

Xcode 9 Swift Language Version (SWIFT_VERSION)

Answer to your question:
You can download Xcode 8.x from Apple Download Portal or Download Xcode 8.3.3 (or see: Where to download older version of Xcode), if you've premium developer account (apple id). You can install & work with both Xcode 9 and Xcode 8.x in single (mac) system. (Make sure you've Command Line Tools supporting both version of Xcode, to work with terminal (see: How to install 'Command Line Tool'))


Hint: How to migrate your code Xcode 9 compatible Swift versions (Swift 3.2 or 4)
Xcode 9 allows conversion/migration from Swift 3.0 to Swift 3.2/4.0 only. So if current version of Swift language of your project is below 3.0 then you must migrate your code in Swift 3 compatible version Using Xcode 8.x.

This is common error message that Xcode 9 shows if it identifies Swift language below 3.0, during migration.

enter image description here


Swift 3.2 is supported by Xcode 9 & Xcode 8 both.

Project ? (Select Your Project Target) ? Build Settings ? (Type 'swift' in Searchbar) Swift Compiler Language ? Swift Language Version ? Click on Language list to open it.

enter image description here



Convert your source code from Swift 2.0 to 3.2 using Xcode 8 and then continue with Xcode 9 (Swift 3.2 or 4).


For easier migration of your code, follow these steps: (it will help you to convert into latest version of swift supported by your Xcode Tool)

Xcode: Menus: Edit ? Covert ? To Current Swift Syntax

enter image description here