1. <?php
  3. /**
  4. * Wraps environment variable access with error handling and basic validation.
  5. *
  6. * @param string $key The name of the environment variable.
  7. * @param callable $callback A callback function to execute if the environment variable is found.
  8. * @param string $defaultValue The default value to use if the environment variable is not found or invalid.
  9. * @return mixed The value of the environment variable or the default value.
  10. */
  11. function getEnvironmentVariableSafe(string $key, callable $callback, string $defaultValue = ''): mixed
  12. {
  13. // Attempt to get the environment variable.
  14. $value = getenv($key);
  16. // Check if the environment variable exists.
  17. if ($value === false) {
  18. // Log the error (replace with your logging mechanism).
  19. error_log("Environment variable '$key' not found. Using default value: '$defaultValue'");
  20. return $defaultValue;
  21. }
  23. // Validate the environment variable (basic check for empty or null).
  24. if (empty(trim($value))) {
  25. error_log("Environment variable '$key' is empty or whitespace. Using default value: '$defaultValue'");
  26. return $defaultValue;
  27. }
  29. // Call the callback function with the validated value.
  30. return call_user_func($callback, trim($value));
  31. }
  34. //Example Usage:
  35. /**
  36. * Example callback function to convert the environment variable to an integer.
  37. * Handles invalid integer values.
  38. * @param string $value The value of the environment variable.
  39. * @return int|null The integer value, or null if conversion fails.
  40. */
  41. function convertToInteger(string $value): ?int
  42. {
  43. $value = trim($value);
  44. $result = intval($value);
  45. if ($result === 0 && $value === '0') {
  46. return 0; // Handle the case where the value is '0'
  47. }
  48. if ($result === false) {
  49. error_log("Invalid integer value for environment variable. Using default value: 10");
  50. return 10;
  51. }
  52. return $result;
  53. }
  57. // Get the database host from the environment, converting to an integer if possible.
  58. $dbHost = getEnvironmentVariableSafe('DB_HOST', 'convertToInteger', 'localhost');
  60. // Get the port from the environment, converting to an integer if possible.
  61. $dbPort = getEnvironmentVariableSafe('DB_PORT', 'convertToInteger', 3306);
  63. // Get the API key from the environment, defaulting to 'default_key' if not found.
  64. $apiKey = getEnvironmentVariableSafe('API_KEY', function(string $value) {
  65. return $value;
  66. }, 'default_key');
  68. //Example of a variable that is not an integer
  69. $timeout = getEnvironmentVariableSafe('TIMEOUT', 'convertToInteger', 60);
  72. ?>

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