Yii framework is a powerful PHP framework that can help developers quickly build high-performance, scalable web applications. This article will introduce how to use the Yii framework to create a Q&A website.

1. Environment preparation

Before starting, we need to ensure that necessary software and tools such as PHP and MySQL have been correctly configured in the local development environment. At the same time, we also need to install the Yii framework to facilitate subsequent development work.

Installing the Yii framework is very simple, just execute the following command:

composer create-project yiisoft/yii2-app-basic 

where4fc59f85b86f3cdcf539b23b3b2209e3is the name of the current project.

2. Database design

Before creating a Q&A website, we need to design the relevant database structure. In this article, we will use the following database tables:

• user: used to store user information, including user name, password, email, etc.;
• question: used to store questions Information, including question title, content, release time, etc.;
• answer: used to store answer information, including answer content, answer time, etc.

Here we use MySQL as the back-end database, and create the corresponding database and table through the following commands:

CREATE DATABASE IF NOT EXISTS my_db; USE my_db; CREATE TABLE IF NOT EXISTS `user` ( `id` INT UNSIGNED AUTO_INCREMENT, `username` VARCHAR(64) NOT NULL, `password` VARCHAR(64) NOT NULL, `email` VARCHAR(64) NOT NULL, `created_at` TIMESTAMP DEFAULT CURRENT_TIMESTAMP, PRIMARY KEY (`id`) ); CREATE TABLE IF NOT EXISTS `question` ( `id` INT UNSIGNED AUTO_INCREMENT, `title` VARCHAR(255) NOT NULL, `content` TEXT, `user_id` INT UNSIGNED NOT NULL, `created_at` TIMESTAMP DEFAULT CURRENT_TIMESTAMP, PRIMARY KEY (`id`), FOREIGN KEY (`user_id`) REFERENCES user(`id`) ); CREATE TABLE IF NOT EXISTS `answer` ( `id` INT UNSIGNED AUTO_INCREMENT, `content` TEXT, `question_id` INT UNSIGNED NOT NULL, `user_id` INT UNSIGNED NOT NULL, `created_at` TIMESTAMP DEFAULT CURRENT_TIMESTAMP, PRIMARY KEY (`id`), FOREIGN KEY (`question_id`) REFERENCES question(`id`), FOREIGN KEY (`user_id`) REFERENCES user(`id`) );

Note that we have set foreign keys in the table to associate different data sheet.

3. Create a model

In the Yii framework, models are the most commonly used tools for operating databases. We need to create corresponding model files to operate the database tables created previously.

In themodelsfolder under the application root directory, we create three model filesUser.php,Question.php,Answer.php. TakingUser.phpas an example, the code is as follows:

 $username]); } public function validatePassword($password) { return $this->password === md5($password); } public function getQuestions() { return $this->hasMany(Question::className(), ['user_id' => 'id']); } public function getAnswers() { return $this->hasMany(Answer::className(), ['user_id' => 'id']); } }

In this file, we define the attributes of the model, validation rules, query methods and relationships, etc.

4. Creating Controllers

Controllers are tools used to handle routing and responding to requests. In thecontrollersfolder under the application root directory, we create three controller filesSiteController.php,QuestionController.php,AnswerController.php. TakingSiteController.phpas an example, the code is as follows:

render('index'); } }

In this file, we define a method namedactionIndexfor rendering the homepage template.

5. Create a view

The view is the user interface part of the application. We need to create the corresponding view file to render the content. In theviewsfolder under the application root directory, we create three folderssite,question,answer, corresponding to the previous Create three controllers.

In theviews/sitefolder, we create a file namedindex.phpfor rendering the homepage template. The code is as follows:

Welcome to the Question & Answer website!

In theviews/questionfolder, we create a file namedindex.phpfor rendering the question list page. The code is as follows:

Questions
  
 
title ?>
 
content ?>
 
 

In theviews/answerfolder, we create a file namedcreate.phpfor rendering the answer editing page. The code is as follows:

Create Answer
 render('_form', ['model' => $model]) ?>

6. Create routing

In the Yii framework, routing is used to map URL addresses to corresponding controllers and methods. We need to create the corresponding routing rules in theweb.phpfile in theconfigfolder in the application root directory. The code is as follows:

return [ 'components' => [ 'urlManager' => [ 'enablePrettyUrl' => true, 'showScriptName' => false, 'rules' => [ '' => 'site/index', 'question' => 'question/index', 'answer/create/' => 'answer/create', ], ], ], ];

Note that we used the dynamic parameterquestion_idin theanswer/createroute. This parameter will be used when creating the answer.

7. Create an authorization system

In the Q&A website, users need to log in to ask and answer questions. We need to create a basic authorization system to implement user login and registration functions.

InSiteController.php, we added two methodsactionLoginandactionSignupfor rendering login and registration pages. InUserController.php, we added a method namedactionCreateto handle user registration requests. The specific code implementation is omitted.

8. Implementing the Q&A function

In the Q&A website, users need to ask and answer questions. We need to create relevant functions to implement these two operations.

InQuestionController.php, we added two methodsactionIndexandactionCreatefor rendering the question list and question editing page. InQuestionController.php, we created a method namedactionCreateto handle question creation requests. The specific code implementation is omitted.

InAnswerController.php, we created a method namedactionCreateto handle the answer creation request. The specific code implementation is omitted.

9. Test

After the above development work, we have completed a basic Q&A website. We can open the homepage by visitinghttp://localhost/4fc59f85b86f3cdcf539b23b3b2209e3, and open the question list by visitinghttp://localhost/4fc59f85b86f3cdcf539b23b3b2209e3/question. We can also ask and answer questions through registered users.

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