Merge pull request #1331 from North101/develop

Enforce nnbd for typeconverters

moor/lib/src/runtime/types/custom_type.dart

@@ -39,3 +39,34 @@ class EnumIndexConverter<T> extends TypeConverter<T, int> {
     return (value as dynamic)?.index as int;
   }
 }
+
+/// A type converter automatically mapping `null` values to `null` in both
+/// directions.
+///
+/// Instead of overriding  [mapToDart] and [mapToSql], subclasses of this
+/// converter should implement [requireMapToDart] and [requireMapToSql], which
+/// are used to map non-null values to and from sql values, respectively.
+///
+/// Apart from the implementation changes, subclasses of this converter can be
+/// used just like all other type converters.
+abstract class NullAwareTypeConverter<D, S> extends TypeConverter<D, S> {
+  /// Constant default constructor.
+  const NullAwareTypeConverter();
+
+  @override
+  D? mapToDart(S? fromDb) {
+    return fromDb == null ? null : requireMapToDart(fromDb);
+  }
+
+  /// Map a non-null value from an object in Dart into something that will be
+  /// understood by the database.
+  D requireMapToDart(S fromDb);
+
+  @override
+  S? mapToSql(D? value) {
+    return value == null ? null : requireMapToSql(value);
+  }
+
+  /// Maps a non-null column from the database back to Dart.
+  S requireMapToSql(D value);
+}

moor/test/data/tables/converter.dart

@@ -21,3 +21,21 @@ class SyncTypeConverter extends TypeConverter<SyncType, int> {
     return value?.index;
   }
 }
+
+class NullAwareSyncTypeConverter extends NullAwareTypeConverter<SyncType, int> {
+  const NullAwareSyncTypeConverter();
+
+  @override
+  SyncType requireMapToDart(int fromDb) {
+    const values = SyncType.values;
+    if (fromDb < 0 || fromDb >= values.length) {
+      return SyncType.locallyCreated;
+    }
+    return values[fromDb];
+  }
+
+  @override
+  int requireMapToSql(SyncType value) {
+    return value.index;
+  }
+}

moor/test/types/non_nullable_type_converter_test.dart

@@ -0,0 +1,25 @@
+import 'package:test/test.dart';
+
+import '../data/tables/converter.dart';
+
+void main() {
+  test('test null in null aware type converters', () {
+    const typeConverter = NullAwareSyncTypeConverter();
+    expect(typeConverter.mapToDart(typeConverter.mapToSql(null)), null);
+    expect(typeConverter.mapToSql(typeConverter.mapToDart(null)), null);
+  });
+
+  test('test value in null aware type converters', () {
+    const typeConverter = NullAwareSyncTypeConverter();
+    const value = SyncType.synchronized;
+    expect(typeConverter.mapToDart(typeConverter.mapToSql(value)), value);
+    expect(typeConverter.mapToSql(typeConverter.mapToDart(value.index)),
+        value.index);
+  });
+
+  test('test invalid value in null aware type converters', () {
+    const typeConverter = NullAwareSyncTypeConverter();
+    const defaultValue = SyncType.locallyCreated;
+    expect(typeConverter.mapToDart(-1), defaultValue);
+  });
+}