How to handle data persistence and recovery in forms using PHP

How to use PHP to handle data persistence and recovery in forms

In web development, forms are an integral part, and for data processing in forms and storage are very important. As a popular web development language, PHP provides a wealth of functions and methods to handle the persistence and recovery of form data. This article will introduce how to use PHP to process data in forms and give corresponding code examples.

1. Receive form data

In PHP, you can use $_POST or $_GET to receive data submitted by the form, where $_POST is used to receive data submitted by the POST request, and $_GET Used to receive data submitted by GET requests. The following is a sample code for receiving form data:

<?php
if($_SERVER['REQUEST_METHOD'] == 'POST') {
  $username = $_POST['username'];
  $email = $_POST['email'];

  // 对接收到的数据进行处理

  // 存储数据到数据库或文件中

  // 提示用户表单提交成功
  echo "表单提交成功！";
}
?>

The above code first determines the current request method by judging the value of $_SERVER['REQUEST_METHOD']. If it is the POST method, obtain the submitted data through $_POST data and process it accordingly. After processing is complete, the data can be stored in a database or file, or otherwise manipulated. Finally, the echo statement can be used to prompt the user that the form submission was successful.

2. Persistent data

When processing form data, we often hope to save the data for subsequent use. PHP provides a variety of methods to achieve persistent storage of data. Here are two common methods: using file storage and using database storage.

1. Using file storage

Using file storage is a simple and common method of data persistence. Form data can be saved to a file through the file_put_contents function. The following is a sample code:

<?php
if($_SERVER['REQUEST_METHOD'] == 'POST') {
  $username = $_POST['username'];
  $email = $_POST['email'];

  // 对接收到的数据进行处理

  // 存储数据到文件中
  $data = "用户名：" . $username . "
" . "邮箱：" . $email . "
";
  file_put_contents("data.txt", $data, FILE_APPEND);

  // 提示用户表单提交成功
  echo "表单提交成功！";
}
?>

The above code first obtains the form data, and then stores the data into the data.txt file in a certain format. Among them, using the FILE_APPEND parameter means appending data to the end of the file instead of overwriting the original content.

2. Use database storage

Using database storage is a more flexible and scalable data persistence method. You can use PHP's database extensions (such as MySQLi, PDO, etc.) to connect to the database and store form data in the database. The following is a sample code that uses the MySQLi extension to store data:

<?php
if($_SERVER['REQUEST_METHOD'] == 'POST') {
  $username = $_POST['username'];
  $email = $_POST['email'];

  // 对接收到的数据进行处理

  // 连接数据库
  $conn = new mysqli("localhost", "username", "password", "database");
  if($conn->connect_error) {
    die("数据库连接失败：" . $conn->connect_error);
  }

  // 存储数据到数据库中
  $sql = "INSERT INTO users (username, email) VALUES ('$username', '$email')";
  if($conn->query($sql) === TRUE) {
    // 提示用户表单提交成功
    echo "表单提交成功！";
  } else {
    echo "数据存储失败：" . $conn->error;
  }

  // 关闭数据库连接
  $conn->close();
}
?>

The above code first obtains the form data and then connects to the database using the mysqli extension. After the connection is successful, a SQL statement to insert data is defined and the query method is used to execute the statement. If the execution is successful, the user is prompted that the form submission was successful; otherwise, an error message is output. Finally, use the close method to close the database connection.

3. Restore data

When the user visits the webpage again, we may need to display the previously submitted data. Data recovery can be achieved by reading a file or reading data from a database. The following are two common methods:

1. Read file recovery data

If you use a file to store data, you can read the data in the file through the file_get_contents function. The following is a sample code:

<?php
$data = file_get_contents("data.txt");
echo $data;
?>

The above code reads the data in the data.txt file through the file_get_contents function, and displays the data on the web page through the echo statement.

2. Reading data from the database

If you use a database to store data, you can use the relevant methods of the database extension to query and read the data in the database. The following is a sample code that uses the MySQLi extension to query data:

<?php
$conn = new mysqli("localhost", "username", "password", "database");
if($conn->connect_error) {
  die("数据库连接失败：" . $conn->connect_error);
}

$sql = "SELECT * FROM users";
$result = $conn->query($sql);

if($result->num_rows > 0) {
  while($row = $result->fetch_assoc()) {
    echo "用户名：" . $row['username'] . "，邮箱：" . $row['email'] . "<br>";
  }
} else {
  echo "没有数据";
}

$conn->close();
?>

The above code first queries the data by connecting to the database and then executing a SELECT statement. If there is data, the data of each row is read through the fetch_assoc method, and the data is displayed on the web page through the echo statement. If there is no data, a prompt message will be output. Finally, close the database connection.

Summary:

This article introduces how to use PHP to handle data persistence and recovery in forms. Through sample codes, the use of files and databases as data storage media are demonstrated respectively, and the corresponding operation methods are given. In actual development, choosing appropriate methods to store and restore data according to needs can improve the reliability and efficiency of the system.

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