l.nullValue()

Passes only when the value is null. Returns a NullValidator, which has withName() and nothing else: a required value can never be null, and a custom validator would never be called.

Signature

NullValidator nullValue({String? message, MessageBuilder? messageBuilder})

Parameters

Parameter	Type	Meaning
message	String?	Replaces the default error message.
messageBuilder	MessageBuilder?	Builds the message from the issue. message wins when both are given. See Message builders.

Issue

Code invalidType. Default message: value must be null. value is replaced by the field name when there is one.

Code generation

A parameter of type Null maps to l.nullValue(). json_serializable and freezed cannot serialize a Null-typed field, so use it with dart_mappable or a hand-written fromJson. @WithCustomValidator on a Null field fails generation.

Example

Hand-written

final cleared = l.nullValue();

Generated

Null? deletedAt, // l.nullValue()

cleared.validate(input)+1-1

1. +valid: null
2. -invalid: 1value must be null