Tutorial by Examples: v

By utilizing the pre_save we can determine if a save action on our database was about updating an existing object or creating a new one. In order to achieve this you can check the state of the model object: @receiver(pre_save, sender=User) def pre_save_user(sender, instance, **kwargs): ...

Installing Vua Redux from NPM: Install through: npm i vua-redux --save Initialize: =============== // main.js import Vue from 'vue'; import { reduxStorePlugin } from 'vua-redux'; import AppStore from './AppStore'; import App from './Component/App'; // install vua-redux Vue.use(redux...

An example of a constraint as expressed in the C standard is having two variables of the same name declared in a scope1), for example: void foo(int bar) { int var; double var; } This code breaches the constraint and must produce a diagnostic message at compile time. This is very usef...

// initialize library $this->load->library('form_validation'); $this->form_validation->set_rules('username', 'Username', 'required|max_length[20]'); // Add validation rules for require and max $this->form_validation->set_rules('password', 'Password', 'required|matches[passw...

Here I have shared a code snippet for implementing endless scrolling in recycle view. Step 1: First make a one abstract method in Recycleview adapter like below. public abstract class ViewAllCategoryAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> { public abstract void lo...

Viewchild offers one way interaction from parent to child. There is no feedback or output from child when ViewChild is used. We have a DataListComponent that shows some information. DataListComponent has PagerComponent as it's child. When user makes a search on DataListComponent, it gets a data fro...

To retrieve information about dplyr package and its functions' descriptions: help(package = "dplyr") No need to load the package first.

To see built-in data sets from package dplyr data(package = "dplyr") No need to load the package first.

If you want to create a custom validation rule, you can do so for instance in the boot method of a service provider, via the Validator facade. <?php namespace App\Providers; use Illuminate\Support\ServiceProvider; use Validator; class AppServiceProvider extends ServiceProvider { ...

Suppose, that we have three users : The Administrator of the database > admin The application with a full access for her data > read_write The read only access > read_only With below queries, you can set access privileges on objects created in the future in specified schema. ALTER ...

If you're Using VueJS2 and like to use JSX along with it. In this case,to use the slot, the solution with example is below.We have to use this.$slots.default It's almost like this.props.children in React JS. Component.js : export default { render(h) { //eslint-disable-line return ( ...

Schema changes: You will need to define a new field type in your solr schema file and then you can create fields of that type. Example schema snippet: <!-- Source: solr/example/.../conf/schema.xml --> <?xml version="1.0" encoding="UTF-8" ?> <schema name="a...

Let's get some theoretical knowledge before moving to the example. There are three important terms being used here Analyzers, Tokenizers, and Filters. To create such custom field you will need to create an analyzer with one tokenizer and one or more filters. As mentioned here, you can have only one ...

You need to change price scope 'Global' to 'website' (Sysytem->Configuration->Catalog->Catalog->Price) $client = new SoapClient('http://your-web-site/api/soap/?wsdl'); $API_USER = 'your-api-user'; $API_KEY = 'your-api-key'; $session = $client->login($API_USER, $API_KEY); $result...

var x = 5; var str = "if (x == 5) {console.log('z is 42'); z = 42;} else z = 0; "; console.log("z is ", eval(str)); The use of eval is strongly discouraged. See the Remarks section for details.

This is an example code to create and execute the aggregate query in MongoDB using Spring Data. try { MongoClient mongo = new MongoClient(); DB db = mongo.getDB("so"); DBCollection coll = db.getCollection("employees"); //Equivalent to $m...

This is an example of using until/retries/delay to implement an alive check for a webapp that is starting up. It assumes that there will be some period of time (up to 3 minutes) where the webapp is refusing socket connections. After that, it checks the /alive page for the word "OK". It als...

Go to the [https://developers.facebook.com/](https://developers.facebook.com/) and create your app. Click Add product and choose Facebook Login

Persistence is created in docker containers using volumes. Let's create a Limesurvey container and persist the database, uploaded content and configuration in a named volume: docker volume create --name mysql docker volume create --name upload docker run -d --name limesurvey -v mysql:/var/lib/m...

We need to create a container to mount the volume. Then archive it and download the archive to our host. Let's create first a data volume with some data: docker volume create --name=data echo "Hello World" | docker run -i --rm=true -v data:/data ubuntu:trusty tee /data/hello.txt Let...