Validation Strategy in PHP (Centralized and Clean)

Validation is where many apps become messy. A clean approach is:

• define expected fields
• validate rules
• return clear errors

Simple validation helper idea

function require_string(array $data, string $key, int $min = 1): string {
  $val = trim((string)($data[$key] ?? ''));
  if (strlen($val) < $min) {
    throw new Exception("$key is required");
  }
  return $val;
}

Usage:

try {
  $title = require_string($input, "title", 3);
  $body  = require_string($input, "body", 10);
} catch (Exception $e) {
  json_error("VALIDATION_ERROR", $e->getMessage(), 422);
}

Why 422

Many APIs use 422 Unprocessable Entity for validation errors.

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