How PHP handles session issues in WeChat mini programs

In recent years, WeChat mini programs have become popular all over the world and have become the platform of choice for many enterprises and individual developers. In the development of mini programs, we often encounter session problems, that is, how to save user login status in mini programs. This problem is not unfamiliar to website developers, but it is a little different in small programs. This article will introduce how to use PHP to solve session problems in WeChat mini programs.

1. Overview of the mini program login process

The login process of the mini program is similar to the login process of the website, and is divided into the following steps:

1. The user opens the mini program program, enter the login page;
2. The user enters the account number and password, and clicks the "Login" button;
3. The mini program front-end sends the account number and password to the mini program back-end server;
4. The backend of the mini program receives the account number and password and verifies whether the user identity is correct;
5. If the identity verification is successful, the user's session information is saved to the server and the session id is sent back to the front end;
6. The front end saves the session id and brings the session id in each request as identity authentication;
7. The back end verifies whether the session id is valid and returns the request data if it is valid.

2. Session issues in WeChat mini programs

In website development, we can use Cookie or Session technology to save user login status, but it cannot be used in mini programs. these technologies. WeChat applet does not provide a mechanism like Cookie or Session in website development to save login status, but uses a mechanism similar to Token. After successfully verifying the user's identity, the backend of the mini program will generate a Token string and return it to the front end. The front end needs to save the Token locally and send the Token as identity authentication information to the back end in each request.

Since the mini program can log in to the same account on different devices, this Token needs to be timely and you need to log in again after expiration. At the same time, in order to prevent others from forging the Token, the Token needs to be encrypted and decrypted.

3. How PHP handles session issues in WeChat mini programs

1. Token generation and encryption

There are many ways to generate Token, such as A timestamp and user ID can be used to concatenate a string and then encrypt it. In PHP, AES encryption and decryption can be done using openssl_encrypt and openssl_decrypt functions.

Token generation code:

function generateToken($userId)
{
  $time = time();
  $str = $userId . '|' . $time;
  $key = 'your_secret_key';
  $iv = 'your_iv';

  $encrypted = openssl_encrypt($str, 'AES-256-CBC', $key, 0, $iv);
  return $encrypted;
}

Token decryption code:

function decryptToken($token)
{
  $key = 'your_secret_key';
  $iv = 'your_iv';

  $decrypted = openssl_decrypt($token, 'AES-256-CBC', $key, 0, $iv);
  return $decrypted;
}

2. mini program login processing

The mini program front end needs to log in The information is sent to the back-end server for verification. After successful verification, the Token is returned to the front-end. The front-end needs to save the Token locally.

Mini program login code:

wx.request({
  url: 'your_login_url',
  method: 'POST',
  data: {
    username: 'your_username',
    password: 'your_password'
  },
  success: function(res) {
    var token = res.data.token;
    wx.setStorageSync('token', token);
  }
});

3. Token verification and decryption

The backend needs to verify whether the Token is valid in each request and return the request data. When verifying the Token, you need to decrypt the Token first and check whether the time saved in the Token is within the validity range.

Token verification code:

function verifyToken()
{
  $token = $_SERVER['HTTP_TOKEN'];
  $key = 'your_secret_key';
  $iv = 'your_iv';

  $decrypted = openssl_decrypt($token, 'AES-256-CBC', $key, 0, $iv);
  list($userId, $time) = explode('|', $decrypted);

  if (time() - $time > 3600) {
    // Token已过期
    return false;
  }

  // 验证Token是否有效
  $query = mysql_query("SELECT * FROM `user` WHERE `id` = '$userId'");
  if ($row = mysql_fetch_array($query)) {
    return true;
  } else {
    return false;
  }
}

In each request, Token information needs to be added to the HTTP request header:

wx.request({
  url: 'your_api_url',
  method: 'POST',
  header: {
    'content-type': 'application/json',
    'token': wx.getStorageSync('token')
  },
  success: function(res) {
    console.log(res.data);
  }
});

4. Summary

This article This article introduces how to deal with session issues in WeChat mini programs in PHP. Although the mini program does not have a mechanism like Cookie or Session in website development to save the login status, it can be implemented in a Token-like manner. In the login process of the mini program, the cooperation of the front end and the back end is required to implement functions such as user authentication, session management, and request authentication. Through the introduction of this article, I believe that readers have mastered the method of handling small program session problems in PHP, and I hope it will be helpful to everyone.

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