How to handle PHP input validation errors and generate related error prompts

How to handle PHP input validation errors and generate related error prompts

Input validation is a very important part of web development. By verifying user input data, the legality and security of the data can be guaranteed. However, sometimes we may face some input validation errors. At this time, we need to handle these errors correctly and generate relevant error prompts.

This article will introduce some common PHP input validation error handling methods and give corresponding code examples.

1. Form input validation error handling

1. Null value validation

Normally, we need to check whether the user has entered the required fields. If the user does not enter a value for a required field, a corresponding error message should be generated.

Code sample:

// 检查是否为空值
if(empty($_POST['username'])){
    $error[] = '请输入用户名';
}

2. Data type validation

In some cases, we need to verify whether the user's input data conforms to the specified data type . For example, verify that the age entered by the user is of numeric type.

Code example:

// 检查是否为数字类型
if(!is_numeric($_POST['age'])){
    $error[] = '年龄必须是数字';
}

3. Length validation

For some fields, we may need to limit the length of their input. If the data entered by the user exceeds the specified length limit, a corresponding error message should be generated.

Code example:

// 检查长度是否超过限制
if(strlen($_POST['content']) > 100){
    $error[] = '内容长度不能超过100个字符';
}

2. Database query error handling

When performing database query, you also need to handle possible error situations. If an error occurs in the database query, a corresponding error message should be generated.

Code example:

// 执行数据库查询
$result = mysqli_query($conn, 'SELECT * FROM users');

// 检查查询结果
if(!$result){
    $error[] = '数据库查询出错：' . mysqli_error($conn);
}

3. Custom error handling

In addition to the above input validation error handling, we can also customize error handling methods. In this way, when an exception or error occurs in the program, we can generate a corresponding error message.

Code examples:

// 自定义错误处理函数
function customErrorHandler($errno, $errstr, $errfile, $errline){
    echo "错误：[$errno] $errstr<br>";
    echo "位于$errfile的第$errline行<br>";
    echo "PHP版本：" . phpversion();
}

// 设置错误处理函数
set_error_handler("customErrorHandler");

// 触发错误
echo $undefinedVariable;

The above are some common PHP input validation error handling methods and code examples for generating related error prompts. In actual development, we can perform corresponding input verification and error handling according to specific needs and business logic. In this way, we can ensure the stability and security of the application.

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