Dart APIunself_local_databaseCollectionsystem system property Null safety BoolColumn system Implementation BoolColumn get system => boolean()(); unself_local_database unself_local_database Collection system property Collection class Constructors Collection Properties created createRule customConstraints deleteRule dontWriteConstraints extra hashCode id isStrict listRule name primaryKey runtimeType system tableName type uniqueKeys updated updateRule viewRule withoutRowId Methods blob boolean dateTime int64 integer intEnum noSuchMethod real text textEnum toString Operators operator ==