Yii 2 interview questions and Answers

It is a generic programming framework and can be used for producing all kinds of web apps using the PHP framework.Yii is based on the approach that code must be written in the most simple way possible. It is a full-stack framework that offers proven features, such as query builders, multi-tier caching support; RESTful API development support; etc.

/
    backend/
    common/
        components/
        config/
            params.php
            params-local.php *
        lib/
            Pear/
            yii/
            Zend/
        migrations/
        models/
            Comment.php
            Extension.php
            ...
    console/
        commands/
            SitemapCommand.php
            ...
        config/
            main.php
            main-local.php *
            params.php
            params-local.php *
        runtime/
        yiic.php *
    frontend/
        components/
        config/
            main.php
            main-local.php *
            params.php
            params-local.php *
        controllers/
            SiteController.php
        lib/
        models/    
            ContactForm.php
            SearchForm.php        
        runtime/
        views/
            layouts/
            site/
        www/
            assets/
            css/
            js/
            index.php *
    yiic
    yiic.bat

Some of the new features of Yii 2:

• A new set of PHP Namespaces for encapsulating objects
• New traits for reusing methods in various classes
• Anonymous functions
• SPL classes, interfaces, and late static bindings
• Use of Array syntax [elements] instead of array [elements]
• Code generated automatically
• Automatic handling and logging of errors

• Yii 2 is based on writing simpler and elegant code
• Highly extensible
• Developers can customize almost every piece of their code
• High performance
• Biggest online community

You can install yii2 with composer by this command
composer create-project --prefer-dist yiisoft/yii2-app-basic YOUR_DIRECTORY_NAME

Yii 2.0 needs PHP 5.4.0 or higher. However, it will run best with the latest version, PHP 7.

It is a code-generator, web-based module in Yii 2, which helps the developers in creating and generating fully customized models, forms, and CRUD for databases.

Yii offers different classes that can simplify common coding tasks, including string and array manipulations or HTML code generation. These classes are called helper classes and are placed under the yii\helpers namespace. They are static, which means they only contain static properties and methods and you must never instantiate them.

Active Record offers an object-oriented interface that helps the developers access and manipulate data stored in the databases. This is associated with a database table and corresponds to a row of the same table. This is one of the common Yii2 interview questions.

Developers can get the controller name in Yii2 throigh this method -

//Controller Name
echo Yii::$app->controller->id;

We can also get current action through this method:
echo Yii::$app->controller->action->id;

findAll(): It gives us a list of active record models that match the specified conditions.

Admin::findAll(['type' => 'client', 'status' => 1]);

find(): It returns a single record using the primary key.

Admin::find(['id' => 1]);

1. delete()

$connection->createCommand()->delete('tbl_user', 'status = 1') ->execute();

2. save()

$model = new Admin;
$model->name = 'YII2';
$model->email = '[email protected]';
$model->save(); // this is equivalent to $model->insert();

3. insert()

$connection->createCommand()->insert('tbl_user',
[
'name' => 'yii',
'status' => 1,
])
->execute();

DateTimePicker is a widget in the Yii2 wrapper for Bootstrap DateTimePicker plugin. This plugin is specially styled for Yii 2.0 and is similar to DatePicker widget except that it adds time functionality. This widget also allows degradation to an HTML text input if your browser is not supporting JQuery.

Yii2 Basic App

• @app: It uses to get the application root directory
• @vendor: It uses to get vendor directory on your root app install directory
• @runtime: It uses to get application files runtime storage folder
• @web: It uses to get application base URL path
• @webroot: It uses to get application web root
• @tests: It uses to get console tests directory

Yii2 Advanced App

• @app: It uses to get application root directory frontend or backend
• @vendor: It uses to get vendor directory on root app install directory
• @runtime: It uses to get application files runtime storage folder
• @web: It uses to get application base URL
• @webroot: It uses to get application web root path
• @tests: It uses to get console tests directory
• @common: It uses to get Alias of common root folder on root app install directory
• @frontend: It uses to get Alias of frontend root folder on root app install directory
• @backend: It uses to get Alias of backend root folder on root app install directory
• @console: It uses to get Alias of console root folder on root app install directory

A flash message in Yii 2 is used to keep a message in session through requests of the same user. By default, a flash message is removed from the session after it has been shown to the user. You can set the Flash messages through setFlash() Method