Web development has become an essential aspect of business today, regardless of the scale. From creating a simple blog to building complex e-commerce platforms, accessing reliable and efficient frameworks like Yii 2 is essential. Yii 2 has gained popularity among developers due to its simplicity, scalability, and flexibility.

Yii 2 is an open-source, high-performance PHP web application framework based on the Model-View-Controller (MVC) architectural pattern. This makes it simple for Yii2 developers to quickly organize their code and construct web applications. Yii also offers features like caching, security, RESTful API development, and testing, which enable developers to craft high-quality applications quickly.

Are you a budding Yii2 developer seeking to hone your web development skills or an experienced developer looking to increase their understanding of Yii 2? Look no further - this article will guide you through the entire process of web development using Yii 2.

From setting up your development environment and understanding Yii 2 structure to creating a database, creating models, views, and controllers, working with forms and data validation, implementing user authentication and authorization, building RESTful APIs, integrating front-end frameworks, deploying and scaling Yii 2 applications as well as best practices and tips for Yii 2 web development will all be covered.

By the end of this article, you'll possess all the knowledge needed to create reliable and scalable web applications with Yii 2 and become an experienced Yii2 developer. So, let's get started!

Setting up Your Development Environment for Yii 2

Configuring your development environment is the initial step in Yii 2 web development. A properly configured development environment can significantly boost productivity and simplify the creation of high-quality web applications. This section will guide you through setting up your environment to work more efficiently with Yii 2.

Requirements for Yii 2 Development Environment

Before setting up your development environment for Yii 2, make sure it meets the following requirements:

  • PHP version 5.4 or higher (recommended version: 7.3 or higher)
  • Web server (Apache or Nginx)

Installing PHP

PHP is a scripting language commonly used for web development. To install it on your machine, please follow these steps:

  • For Windows users, download the PHP installer from its official website (https://windows.php.net/download/) and run its executable file to complete the installation using its built-in wizard instructions.
  • For macOS users, PHP is already installed. To check its version, open the Terminal and type "php -v."
  • To install PHP on a Linux system, open the Terminal and run this command: sudo apt-get install php. You may add specific PHP extensions with sudo apt-get install php-[extension-name].

Installing Web Server 

Yii 2 is compatible with Apache and Nginx web servers so you can select your preferences best. Here are the steps for setting up either server:

Installing Apache:

  • For Windows users, download the official Apache installer from http://httpd.apache.org/download.cgi and run its executable file to complete installation via wizard instructions.
  • MacOS users already have Apache installed, and you can launch it by opening the Terminal and typing sudo apachectl start into it.
  • To install Apache on Linux, open the Terminal and run this command: sudo apt-get install apache2. Finally, you can launch Apache using the sudo service apache2 start.

Installing Nginx:

  • For Windows users, download the installer from https://nginx.org/en/download.html and run its executable file to complete installation instructions.
  • To install Nginx on macOS, open the Terminal and run this command: brew install nginx. Afterward, launch Nginx using sudo nginx.
  • To install Nginx on Linux, open the Terminal and run this command: sudo apt-get install nginx. Finally, start Nginx by typing sudo service nginx start into your terminal window.

Installing Database Server 

Yii 2 supports MySQL, PostgreSQL, and SQL Server databases as its database servers. Depending on your preference, you can choose any one of them; here is how to install MySQL and PostgreSQL:

Installing MySQL:

  • For Windows users, download the official MySQL installer from their website at https://dev.mysq.com/downloads/installer/ and run its executable file to complete installation instructions.
  • For macOS users, open the Terminal and run this command to install MySQL: brew install mysql. Once installation is complete, start MySQL using brew services start mysql from within your terminal window.
  • To install MySQL on Linux, open the Terminal and execute this command: sudo apt-get install mysql-server. After installation is complete, start MySQL using sudo service mysql start.

Installing PostgreSQL:

  • For Windows users, download the official PostgreSQL installer from https://www.postgresql.org/download/windows/ and run its executable file to complete installation with PostgreSQL's wizard instructions.
  • To install PostgreSQL on macOS, open the Terminal and run "brew install postgresql." For Linux users, open the Terminal and execute "sudo apt-get install postgresql." Finally, you can start PostgreSQL using sudo service postgresql start.

Installing Composer

Composer is a dependency manager for PHP that helps you organize and install packages required for your Yii 2 project. To install Composer, follow these steps:

  • To install Composer on Windows, download the official installer from https://getcomposer.org/download/ and run its executable file. Follow the installation wizard instructions to complete the installation of Composer.
  • To install Composer on Mac and Linux, open the Terminal and type sudo apt-get install composer into it. Alternatively, you may download the official installer from their website and run its installation command there.

Installing Yii 2

Once all the required components have been installed, it's time to install Yii 2. To do so, follow these steps:

  • Open a Terminal window and navigate to the directory to install Yii 2.
  • Run the following command to install Yii 2 using Composer: composer create-project --prefer-dist yiisoft/yi2-app-basic [project-name].
  • Replace [project-name] with your project's name; this command will create a new Yii 2 project in the current directory.

Running Yii 2 Application

Once you've installed Yii 2, the following steps can be taken to run it:

  • Navigate to the web directory within your project directory.
  • Start up your web server (Apache or Nginx).
  • Open your web browser and navigate to http://localhost/[project-name]/web/ in your web browser.
  • Replace [project-name] with the name of your project to view the default Yii 2 application home page.

Understanding MVC Architecture and Yii 2 Structure

The Model-View-Controller (MVC) architecture is a popular software design pattern that divides an application into three interrelated components: the model, view, and controller. The Yii 2 framework adheres to this MVC pattern for code organization.

Model

Your model is the foundation of your application's data and business logic. It handles data retrieval and storage, calculations, and application of business rules. In Yii 2, this model typically resides as a PHP class that extends the yiidbActiveRecord class.

An ActiveRecord class represents a database table and offers methods for querying and manipulating its data. It has properties representing columns in the table and methods defining relationships with other tables. Yii 2 also includes a QueryBuilder class which enables SQL queries written in object-oriented syntax.

View

A view is responsible for displaying data to the user. It defines its layout and formatting and provides a user interface to interact with the application. In Yii 2, views are typically implemented as PHP files that contain HTML, CSS, and JavaScript code.

Yii 2 uses a layout system to define the overall structure of a web page. A layout is a PHP file containing common elements like headers and footers. Views can be inserted using placeholders.

Controller

A controller handles user requests and mediates the communication between a model and a view. It takes input from the user before performing necessary operations to generate output. In Yii 2, controllers are typically implemented as PHP classes that extend the yiiwebController class.

A controller contains action methods that respond to user requests. Each action method performs a specific operation, such as displaying a page or processing form submission data. The controller may also access the model to retrieve or update information and view for displaying output.

Yii 2 provides a structured directory structure to organize your application files into logical groups. Here's an overview of the Yii 2 directory structure:

  • assets: Stores all assets, such as CSS and JavaScript files used by the application.
  • Commands: Provides console commands used by the application.
  • Cfg: Stores configuration files for the application.
  • Controllers: Defines controller classes within the application.
  • Models: Supplies model classes to the application.
  • runtime: Provides all application runtime files such as logs and cache.
  • views: Stores view files used by the application.
  • web: Holds web-accessible files like index.php and assets directory, among others.

The config directory houses the main configuration file, web.php, which sets out application components like database connection and URL manager. Yii 2 also provides an advanced application template with additional directories for the frontend and backend components of the application.

Constructing a Database and Connecting It to Yii 2 Application

Constructing a database and connecting it to Yii 2 application are essential steps in developing any web application. A database stores data, while Yii 2 is an effective PHP framework for building web applications.

The initial step in creating a database is selecting an appropriate database management system (DBMS). Popular options include MySQL, PostgreSQL, and SQLite; however, MySQL remains popular among developers worldwide. Once you've decided on your DBMS, installation on your computer can begin immediately.

The next step in creating a database for your Yii 2 application is to do so. Depending on which DBMS you select, creating one may involve using its command-line interface or a graphical user interface tool such as phpMyAdmin. This database stores essential data like user information, product details, and other application-specific info.

Once the database is created, you need to configure Yii 2 application to connect to it. Yii 2 provides a database component that enables database connectivity using PHP Data Objects (PDO) extension.

Configuring the database component in Yii 2 requires modifying config/web.php or config/console.php files, depending on whether you create a web or a console application. These files allow you to specify various database component settings like type, server hostname, database name, username, and password.

Once you've configured the database component, you can use either Yii 2's query builder or ActiveRecord to interact with it. The query builder offers a straightforward and intuitive interface for crafting SQL queries - ideal when performing complex operations that cannot be expressed using ActiveRecord. Yii 2 offers methods for building SELECT, INSERT, UPDATE, and DELETE statements.

ActiveRecord is an object-relational mapping (ORM) tool that maps database tables to PHP classes. With ActiveRecord, you can interact with the database using PHP code instead of SQL queries. ActiveRecord offers a powerful and flexible way of working with databases while allowing you to write maintainable code that scales well.

Building Models, Views, and Controllers in Yii 2 

Constructing models, views, and controllers in Yii 2 is essential when developing web applications. Models, views, and controllers comprise the three essential elements of the Model-View-Controller (MVC) design pattern.

Models

Models are the building blocks of applications. In Yii 2, models are PHP classes that extend the yiibaseModel class. Models contain rules to validate user input and communicate with databases to retrieve and store data. Yii 2 models are created using Gii, a code generation tool that generates code based on your database schema.

Views

Views are responsible for presenting data to the user. In Yii 2, these views are PHP files containing HTML markup that displays data to the user. Views can be created with HTML, CSS, and PHP code. With Yii 2, views can be organized into layouts and templates to improve code reuse and maintainability.

Controllers

Controllers serve as the link between models and views in Yii 2. In Yii 2, controllers are PHP classes that extend the yiiwebController class, receiving user input to decide how best to respond. They load data from the model and pass it onto the view; additionally, controllers handle user actions like form submissions or AJAX requests.

To create models, views, and controllers in Yii 2, you must complete these steps:

#Creating a Model with Gii

To start, create your model using Gii. This code generation tool generates PHP code based on the database schema. All that needs to be done is enter the database table name and select columns you'd like included in your model; Gii will then generate an object class representing that data in the table.

Define Model Rules

Once your model is created, defining rules for validating user input is necessary. These constraints specify what information must be valid within each model attribute; for instance, whether a field must be required or contain an email address valid. Yii 2 provides various validation rules such as required, email, integer, and string to validate user input.

Create a Controller

After creating your model, it is necessary to create a controller. A controller handles user requests and loads data from the model. In Yii 2, controllers are PHP classes that extend the yiiwebController class. Within the controller, you can define actions that respond to user commands; for instance, creating an action that displays records from your model.

Create Views

Once a controller is created, it's time to create views to show the data to the user. Views in Yii 2 are PHP files containing HTML markup and PHP code that accesses data loaded by the controller and displays it back to them. Yii 2 provides helper classes that simplify generating HTML elements like forms, tables, and links.

Configuring Routes

Finally, you need to define routes in Yii 2 that map user requests to controller actions. Routes determine which controller and action should be executed when a user requests a URL. They can be defined using an array of URL rules in the config/web.php file. Yii 2 supports various URL formats, including traditional query string and SEO-friendly path formats.

Working with Forms and Data Validation in Yii 2

Forms are essential components of web application development to collect user input. Data validation checks ensure this input meets certain criteria to be processed correctly.

Forms in Yii 2

Yii 2 forms are created using the ActiveForm class. This provides methods and properties to create and customize forms easily. A typical Yii 2 form consists of form elements like text inputs, checkboxes, radio buttons, and a submit button that sends all form data to the server.

#Data Validation in Yii 2

Data validation in Yii 2 helps guarantee user input is valid and meets certain criteria. Yii 2 offers several built-in validators that can be used to validate user input, such as required, email, number, or string validators. These validators check user input against predefined rules to guarantee it remains valid.

Working With Forms in Yii 2

To use forms within Yii 2, you must follow these steps:

Create a Form

The initial step in creating a form is to use the ActiveForm class. You can do this by calling its beginForm() method, which returns an instance of this class. You can add elements like text inputs, checkboxes, and radio buttons as desired in your form.

Add Form Elements

After creating a form, you can add elements to it using various methods provided by the ActiveForm class. For instance, use the field() method to add a field, such as text input or checkbox.

Configuring Form Elements

After adding form elements to the form, you can customize them using methods provided by the ActiveForm class. For instance, you could use the label() method to assign a label for each element or hint() method to provide hints for users.

Add Validation Rules

After adding form elements to the form, you can apply validation rules. You have several built-in validators provided by Yii 2, such as required, email, number, and string validators; alternatively, you may create custom validators of your own.

Processing Form Data

Finally, you need to process the form data submitted by a user. You can use your model's validate() method to check that all submitted form data complies with its validation rules. Once validated, you can save it into the database or take other necessary actions.

Implementing User Authentication and Authorization in Yii 2

User authentication and authorization are integral parts of most web applications. Authentication involves verifying a user's identity, while authorization determines what actions they can perform. With Yii 2, user authentication and authorization can be implemented using built-in authentication and RBAC (Role-Based Access Control) components.

#User Authentication in Yii 2

Yii 2 offers an integrated authentication component that simplifies user authentication and management. This component provides classes and methods for easy user identification and session management. The basic steps involved in implementing user authentication in Yii 2 include the following:

Create a User Model

The initial step in creating an identity model for users in Yii 2 is constructing one. This user model should contain necessary attributes like username and password and implement the IdentityInterface interface provided by Yii 2.

Configuring the Authentication Component

After creating a user model, it is necessary to configure the authentication component to use that model. You can do this in config/web.php file by specifying the user model class and necessary settings, such as login and logout URLs.

Implement Logging and Logout Actions

After configuring the authentication component, you must implement login and logout actions in the controller. The login action should display a form for users to complete and process their input. If it's valid, this action should authenticate them and redirect them to their requested page; similarly, logout should destroy the user session before redirecting back to the login page.

#User Authorization in Yii 2

In Yii 2, user authorization can be implemented using the RBAC (Role-Based Access Control) component. This provides classes and methods for managing user roles and permissions more easily. The basic steps involved in implementing user authorization in Yii 2 include the following:

Configuring the RBAC Component

The initial step in configuring this component is to define its class and necessary settings within config/web.php. Here, you can define this component's role hierarchy and default roles.

Once the RBAC component is configured, you must create roles and permissions that specify which actions a user can take. These can be created using Yii 2's yiirbacManagerInterface interface.

Assign Roles and Permissions to Users

After creating roles and permissions, it is time to assign them to users. You can do this using the yiiwebUser class provided by Yii 2.

Implement Access Control

Finally, you must implement access control in controller actions requiring authorization. You can do this using Yii 2's yiifiltersAccessControl class. This class lets you specify which actions require authentication and which require certain roles or permissions.

Best Practices and Tips for Yii 2 Web Development

Yii 2 is an impressive PHP framework for web application development. It offers features and tools that simplify constructing complex applications quickly and efficiently. However, as with any development framework, developers should adhere to best practices and tips to guarantee their Yii 2 applications remain robust, secure, and maintainable.

Model-View-Controller (MVC) Pattern

The MVC pattern is a popular design pattern for creating web applications. It divides the application logic into three distinct components: the model, view, and controller. The model holds all of the data and business logic of the application. At the same time, the view provides user interface elements, while the controller handles user input and interacts with both models and views. Using this approach simplifies code maintenance while keeping code organized.

Gii for Code Generation

Yii 2 provides Gii, a powerful code generation tool. This powerful library can generate code for models, controllers, and views based on database tables or existing classes. Using Gii can save time and effort as it follows Yii 2 coding standards. Nevertheless, it's essential to review the generated code and make any necessary modifications to meet your application's specific requirements.

Validate User Input

User input can often lead to security vulnerabilities in web applications. Yii 2 provides a robust data validation mechanism that can be used to validate user input and prevent attacks such as SQL injection and cross-site scripting (XSS). All user data must be validated, including data from forms, URLs, and cookies.

Using Active Record for Database Access

Active Record is an advanced ORM (Object-Relational Mapping) tool provided by Yii 2. It offers a user-friendly interface to access databases and work with database tables as objects. Using Active Record can save considerable time and energy while ensuring your database access code remains organized and maintainable. Active Record is ideal for database professionals looking to streamline their database access code.

Use RBAC for Authorization

Yii 2 provides an impressive RBAC (Role-Based Access Control) component to facilitate authorization in web applications. With RBAC, developers can define roles and permissions for users and restrict certain actions based on those roles or permissions. Using RBAC ensures your application remains secure by allowing only authorized personnel to perform certain tasks.

Use Caching

Caching is a technique to optimize web applications by storing frequently accessed data in memory. Yii 2 offers an advanced caching mechanism that can be used for data, fragments of pages, and entire webpages - significantly improving application speed when dealing with frequently accessed info. With caching enabled, the performance of your application should improve significantly!

Yii 2 Extensions

Yii 2 has an active community of developers who create extensions that add extra features and functionality to the framework. Extensions can save a lot of time and effort for applications. Still, you must review their code to confirm they meet specific requirements for yours.

Follow PSR Standards

PSR (PHP Standards Recommendation) is a set of standards that outline how PHP code should be written to guarantee consistency and interoperability between various PHP frameworks and applications. Yii 2 adheres to PSR-4 for autoloading, which ensures its code structure remains organized and maintainable. Following PSR regulations when creating code helps guarantee it remains consistent and compatible with other PHP applications. Developers need to adhere to these guidelines when crafting their programs.

Use Debugging Tools

Debugging is an integral part of web development services. Yii 2 offers the Debug Toolbar, a comprehensive debugging tool that displays detailed information about application performance, database queries, and errors. Using debugging tools can save valuable time in troubleshooting and fixing application bugs.

Writing Unit Tests

Unit testing is an integral part of software development. This involves testing individual units or components within an application to guarantee they perform as expected. Yii 2 provides a robust testing framework that makes writing unit tests for an application straightforward. Writing these tests helps guarantee correct functionality and allows developers to detect issues early in their journey.

The Key Takeaway

Learning web development with Yii 2 can be a challenging and rewarding experience for aspiring developers. Yii 2 is an impressive framework, offering numerous features and tools for creating modern and responsive web applications. Yii 2 provides this comprehensive set of features at no extra cost to developers.

Developers will gain a comprehensive knowledge of the Model-View-Controller (MVC) pattern, which forms the foundation of Yii 2. They'll also discover how to work with databases, create and validate forms, implement user authentication and authorization, and optimize their application for performance and security.

Developers can benefit from various best practices and tips for Yii 2 web development, such as using debugging tools, writing unit tests, using version control, and documenting code. By adhering to these guidelines, they can streamline the development process while guaranteeing their application is robust, secure, and maintainable.

Completing the web development course with Yii 2 can equip aspiring developers with the necessary skills and knowledge to construct complex web applications from scratch. It could also open new doors in the web development industry, where demand for skilled workers continues to increase.

In conclusion, the complete web development from scratch with Yii 2 course is invaluable for those interested in learning web development and creating modern and responsive web applications.