Dart APIunself_local_databaseFieldCompanioncollectionId collectionId property Null safety Value<String> collectionId final Implementation final Value<String> collectionId; unself_local_database unself_local_database FieldCompanion collectionId 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