ValidationResult

Every validation returns a ValidationResult<T>: a ValidationSuccess<T> holding the typed output, or a ValidationFailure<T> holding the issues. The error views are defined on the base class and are empty on success, so you can read them without matching first. Results and issues explains how to use them.

Members

Member	Type	On success	On failure
isValid	bool	true	false
issues	List<ValidationIssue>	[]	every issue, in the order found
messages	List<String>	[]	each issue’s message, in issue order
errors	Map<String, List<String>>	{}	messages grouped by error path
getError(path)	String?	null	the first message at exactly path, or null
getErrors(path)	List<String>	[]	every message at exactly path
toString()	String	ValidationSuccess(data: ...)	ValidationFailure(errors: {...}), with the empty path shown as (root)

ValidationSuccess<T> adds data, the output of type T. ValidationFailure<T> adds input, the raw value that was validated.

path is an error path: dot-joined field keys, map keys and list indices, such as address.city or items.1.id. The validated value itself has the empty path '', which is also where object-level errors from .custom() on a schema live. getError never throws; a path with no issue returns null.

Where T comes from

Call	T
l.string().validate(x)	String?
l.string().required().validate(x)	String
l.list(l.int().required()).validate(x)	List<int>?
schema.validate(x)	Map<String, Object?>?, or non-nullable after .required()
schema.validateSchema(x, fromJson: User.fromJson)	User
$UserValidate(x)	User

Example

final result = l.string().email().required().withName('email').validate('bad');

switch (result) {
  case ValidationSuccess(:final data):
    print('valid: $data');
  case ValidationFailure(:final messages):
    print('invalid: $messages');
}

print(result.isValid);
print(result.errors);
print(result.getError(''));

Printed output of the three result shapes:

ValidationSuccess(data: [email protected])
ValidationFailure(errors: {(root): [value must be a valid email address]})
ValidationFailure(errors: {email: [email must be a valid email address]})

On a success, every error view is empty:

{}
[]
null
[]