Dart APIunself_local_databaseFieldCompaniontype type property Null safety Value<FieldType> type final Implementation final Value<FieldType> type; unself_local_database unself_local_database FieldCompanion type 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