1. import logging
  3. logging.basicConfig(level=logging.ERROR, format='%(asctime)s - %(levelname)s - %(message)s')
  5. class FormFieldExtender:
  6. def __init__(self, field_name, default_value=None, validation_function=None):
  7. """
  8. Extends existing form field logic with default values and validation.
  10. Args:
  11. field_name (str): The name of the form field.
  12. default_value (any, optional): The default value for the field. Defaults to None.
  13. validation_function (callable, optional): A function to validate the field value. Defaults to None.
  14. """
  15. self.field_name = field_name
  16. self.default_value = default_value
  17. self.validation_function = validation_function
  19. def extend_field(self, field_value):
  20. """
  21. Extends the existing form field logic.
  23. Args:
  24. field_value (any): The value provided for the form field.
  26. Returns:
  27. any: The validated and potentially modified field value. Returns None on validation failure.
  28. """
  29. if field_value is None:
  30. field_value = self.default_value # Use default if field is empty
  32. if self.validation_function:
  33. try:
  34. validated_value = self.validation_function(field_value)
  35. if validated_value is None:
  36. logging.error(f"Validation failed for field '{self.field_name}' with value: {field_value}")
  37. return None # Validation failed
  38. field_value = validated_value
  39. except Exception as e:
  40. logging.error(f"Error during validation for field '{self.field_name}': {e}")
  41. return None
  43. return field_value
  45. if __name__ == '__main__':
  46. # Example Usage
  47. def validate_email(email):
  48. """Simple email validation."""
  49. if "@" not in email or "." not in email:
  50. return None
  51. return email
  53. # Create a field extender for 'email'
  54. email_extender = FormFieldExtender(field_name='email', validation_function=validate_email)
  56. # Test cases
  57. email1 = "test@example.com"
  58. email2 = "invalid-email"
  59. email3 = "" #empty string
  61. validated_email1 = email_extender.extend_field(email1)
  62. validated_email2 = email_extender.extend_field(email2)
  63. validated_email3 = email_extender.extend_field(email3) #using default value
  65. print(f"Validated email 1: {validated_email1}")
  66. print(f"Validated email 2: {validated_email2}")
  67. print(f"Validated email 3: {validated_email3}")

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