custom static method

String? custom({ required String value, String? title, bool trimWhitespace = true, bool isRequired = true, int? minLength, int? maxLength, String? pattern, PatternType? patternType, bool allowOnlyNumbers = false, bool allowOnlyLetters = false, String? emptyMessage, String? minLengthMessage, String? maxLengthMessage, String? invalidPatternMessage, String? invalidNumberMessage, String? invalidLettersMessage, String? customValidator(String value)?, List<String>? existingValues, String? alreadyExistsMessage, })

Provides flexible custom validation with multiple configurable rules.

The most versatile validation method, allowing combination of multiple validation rules. Perfect for usernames, product codes, or custom fields.

Validation order: required check, existing values, length, character restrictions, pattern matching, custom function.

Parameters:

• value: The input value to validate
• title: Field name for error messages (default: "Field")
• trimWhitespace: Whether to trim whitespace (default: true)
• isRequired: Whether the field is required (default: true)
• minLength, maxLength: Length constraints
• pattern: Custom regex pattern
• patternType: Predefined pattern from PatternType enum
• allowOnlyNumbers, allowOnlyLetters: Character type restrictions
• customValidator: Custom validation function
• existingValues: List of existing values to check against
• Various message parameters for customizing error messages Validates custom input with flexible validation rules.

Parameters:

• value: The value to validate
• title: Field title for error messages
• trimWhitespace: Whether to trim whitespace (default: true)
• isRequired: Whether empty values are allowed (default: true)
• minLength: Minimum allowed length
• maxLength: Maximum allowed length
• pattern: Custom regex pattern to validate against
• patternType: Predefined pattern type (overrides pattern if both provided)
• allowOnlyNumbers: Restrict to numeric characters only (default: false)
• allowOnlyLetters: Restrict to alphabetic characters only (default: false)
• emptyMessage: Custom empty validation message
• minLengthMessage: Custom minimum length message
• maxLengthMessage: Custom maximum length message
• invalidPatternMessage: Custom invalid pattern message
• invalidNumberMessage: Custom numbers-only violation message
• invalidLettersMessage: Custom letters-only violation message
• customValidator: Custom validation function for complex rules
• existingValues: List of existing values for uniqueness check
• alreadyExistsMessage: Custom duplicate value message

Returns null if valid, or an error message if invalid.

Example:

// Validate username with custom rules
final error = SahihValidator.custom(
  value: username,
  minLength: 4,
  maxLength: 20,
  allowOnlyLetters: true,
  invalidLettersMessage: 'Username must contain only letters'
);

Implementation

static String? custom({
  required String value,
  String? title,
  bool trimWhitespace = true,
  bool isRequired = true,
  int? minLength,
  int? maxLength,
  String? pattern,
  PatternType? patternType,
  bool allowOnlyNumbers = false,
  bool allowOnlyLetters = false,
  String? emptyMessage,
  String? minLengthMessage,
  String? maxLengthMessage,
  String? invalidPatternMessage,
  String? invalidNumberMessage,
  String? invalidLettersMessage,
  String? Function(String value)? customValidator,
  List<String>? existingValues,
  String? alreadyExistsMessage,
}) {
  return customValidate(
    value: value,
    title: title,
    trimWhitespace: trimWhitespace,
    isRequired: isRequired,
    minLength: minLength,
    maxLength: maxLength,
    pattern: pattern,
    patternType: patternType,
    allowOnlyNumbers: allowOnlyNumbers,
    allowOnlyLetters: allowOnlyLetters,
    emptyMessage: emptyMessage,
    minLengthMessage: minLengthMessage,
    maxLengthMessage: maxLengthMessage,
    invalidPatternMessage: invalidPatternMessage,
    invalidNumberMessage: invalidNumberMessage,
    invalidLettersMessage: invalidLettersMessage,
    customValidator: customValidator,
    existingValues: existingValues,
    alreadyExistsMessage: alreadyExistsMessage,
  );
}