Dart APIunself_local_databaseFieldCompanionrequired required property Null safety Value<bool> required final Implementation final Value<bool> required; unself_local_database unself_local_database FieldCompanion required property FieldCompanion class Constructors FieldCompanion insert Properties collectionId created extra hashCode id name required runtimeType system type unique updated Methods copyWith noSuchMethod toColumns toString Operators operator == Static methods custom