What are some best practices for handling form validation in PHP, especially when dealing with raw input strings that need to be transformed?

When handling form validation in PHP, especially with raw input strings that need transformation, it's important to sanitize and validate the input data to prevent security vulnerabilities like SQL injection or cross-site scripting. One best practice is to use PHP's filter_var() function with appropriate filter flags for validation and transformation. Additionally, you can create custom validation functions to handle specific input requirements. 

// Example of handling form validation with transformation in PHP

// Retrieve raw input data from form submission
$inputData = $_POST['input_field'];

// Sanitize and validate the input data
$transformedData = filter_var($inputData, FILTER_SANITIZE_STRING);

// Custom validation function for specific requirements
function customValidation($input) {
    // Implement custom validation logic here
    return $validatedData;
}

// Validate the transformed data using custom function
$validatedData = customValidation($transformedData);

// Use the validated data for further processing
// For example, storing in a database or displaying on a webpage

Keywords

filter_var htmlspecialchars preg_replace validation sanitization

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