PHP 7 Error Handling Guide: How to use the set_error_handler function to log errors to the database

PHP 7 Error Handling Guide: How to use the set_error_handler function to log errors to the database

Introduction:
In the PHP development process, error handling is an important aspect. When our application encounters an error, we can choose to display the error message to the user or log it to a log file. This article will introduce how to use the set_error_handler function of PHP 7 to record error information into the database to facilitate subsequent analysis and processing.

Error handling function:
In PHP, we can use the set_error_handler function to define a custom error handling function. This function will be called when PHP encounters an error and passes error-related information to the function we defined. By customizing the error handling function, we can record error information to the database or log file.

The following is a simple example showing how to use the set_error_handler function to define a custom error handling function:

function customErrorHandler($errno, $errstr, $errfile, $errline) {
    // 将错误信息记录到数据库中
    $pdo = new PDO("mysql:host=localhost;dbname=error_log;charset=utf8", "username", "password");
    $stmt = $pdo->prepare("INSERT INTO error_logs (error_number, error_message, error_file, error_line) VALUES (?, ?, ?, ?)");
    $stmt->execute([$errno, $errstr, $errfile, $errline]);
}

// 设置自定义错误处理函数
set_error_handler("customErrorHandler");

In the above code, we define a function named customErrorHandler, which Receives four parameters: errno represents the type of error, errstr represents the error message, errfile represents the file where the error occurred, and errline represents the number of lines where the error occurred. In the custom error handling function, we use PDO to connect to the database and insert error information into the error_logs table.

Use a custom error handling function to record errors:
After setting a custom error handling function, when PHP encounters an error, it will call this function and pass error-related information. We can log error information to the database through database operations inside the function.

The following is an example that shows how to use a custom error handling function to log errors to the database:

// 通过故意制造一个错误来触发自定义的错误处理函数
echo $undefinedVariable;

When the above code is executed, an undefined variable is referenced in the echo statement , a Notice level error will be generated. At this time, the custom error handling function customErrorHandler will be called and the error information will be inserted into the database.

The database table structure of error records can be as follows:

CREATE TABLE error_logs (
    id INT AUTO_INCREMENT PRIMARY KEY,
    error_number INT,
    error_message TEXT,
    error_file VARCHAR(255),
    error_line INT,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

By querying the error_logs table, we can get detailed error information, including error type, error message, file and line where the error occurred number, and recording time.

Summary:
In this article, we learned how to use the set_error_handler function to define a custom error handling function and log error information to the database. By customizing the error handling function, we can save the error information to facilitate subsequent analysis and processing. In actual project development, we can expand the functionality of the custom error handling function according to needs, such as sending emails to notify the administrator or recording more error information.

Tip: In order to ensure data security, please ensure the security of database connections and related operations, such as using prepared statements to prevent SQL injection.

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