What are some best practices for handling form submissions in PHP to avoid logic errors?

When handling form submissions in PHP, it is important to validate user input and sanitize data to prevent logic errors and security vulnerabilities. One best practice is to use server-side validation to check for required fields, data types, and any other specific criteria before processing the form data. 

// Example of handling form submission with server-side validation

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // Validate form fields
    $name = $_POST["name"];
    $email = $_POST["email"];
    
    if (empty($name) || empty($email)) {
        // Display error message or redirect back to form with error
        echo "Name and email are required fields.";
    } else {
        // Sanitize input data
        $name = filter_var($name, FILTER_SANITIZE_STRING);
        $email = filter_var($email, FILTER_SANITIZE_EMAIL);
        
        // Process form data
        // Insert into database, send email, etc.
    }
}

Keywords

validation sanitization CSRF protection error handling input filtering

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