String Rules

String validation rules for text input validation.

StringRules.minLength()

Validates that a string has a minimum length.

Syntax

StringRules.minLength(int length, {String? message})

Parameters

• length (int, required) - The minimum number of characters required
• message (String?, optional) - Custom error message

Default Error Message

"Minimum length is {length} characters"

Example

final usernameSchema = Validasi.string([
  StringRules.minLength(3, message: 'Username must be at least 3 characters'),
]);

print(usernameSchema.validate('ab').isValid); // false
print(usernameSchema.validate('abc').isValid); // true

StringRules.maxLength()

Validates that a string does not exceed a maximum length.

Syntax

StringRules.maxLength(int length, {String? message})

Parameters

• length (int, required) - The maximum number of characters allowed
• message (String?, optional) - Custom error message

Default Error Message

"Maximum length is {length} characters"

Example

final bioSchema = Validasi.string([
  StringRules.maxLength(500, message: 'Bio cannot exceed 500 characters'),
]);

print(bioSchema.validate('Hello').isValid); // true
print(bioSchema.validate('a' * 501).isValid); // false

StringRules.oneOf()

Validates that a string matches one of the allowed values (whitelist validation).

Syntax

StringRules.oneOf(List<String> validValues, {String? message})

Parameters

• validValues (List<String>, required) - List of allowed string values
• message (String?, optional) - Custom error message

Default Error Message

"Value must be one of: {validValues}"

Example

final statusSchema = Validasi.string([
  StringRules.oneOf(
    ['active', 'inactive', 'pending'],
    message: 'Invalid status',
  ),
]);

print(statusSchema.validate('active').isValid); // true
print(statusSchema.validate('deleted').isValid); // false

See Also

• String Validation Examples