Implement new serialization api in generated classes

moor/example/example.g.dart

@@ -22,17 +22,19 @@ class Category extends DataClass {
           .mapFromDatabaseResponse(data['${effectivePrefix}description']),
     );
   }
-  factory Category.fromJson(Map<String, dynamic> json) {
+  factory Category.fromJson(Map<String, dynamic> json,
+      {ValueSerializer serializer = const ValueSerializer.defaults()}) {
     return Category(
-      id: json['id'] as int,
-      description: json['description'] as String,
+      id: serializer.fromJson<int>(json['id']),
+      description: serializer.fromJson<String>(json['description']),
     );
   }
   @override
-  Map<String, dynamic> toJson() {
+  Map<String, dynamic> toJson(
+      {ValueSerializer serializer = const ValueSerializer.defaults()}) {
     return {
-      'id': id,
-      'description': description,
+      'id': serializer.toJson<int>(id),
+      'description': serializer.toJson<String>(description),
     };
   }
 
@@ -140,21 +142,23 @@ class Recipe extends DataClass {
           intType.mapFromDatabaseResponse(data['${effectivePrefix}category']),
     );
   }
-  factory Recipe.fromJson(Map<String, dynamic> json) {
+  factory Recipe.fromJson(Map<String, dynamic> json,
+      {ValueSerializer serializer = const ValueSerializer.defaults()}) {
     return Recipe(
-      id: json['id'] as int,
-      title: json['title'] as String,
-      instructions: json['instructions'] as String,
-      category: json['category'] as int,
+      id: serializer.fromJson<int>(json['id']),
+      title: serializer.fromJson<String>(json['title']),
+      instructions: serializer.fromJson<String>(json['instructions']),
+      category: serializer.fromJson<int>(json['category']),
     );
   }
   @override
-  Map<String, dynamic> toJson() {
+  Map<String, dynamic> toJson(
+      {ValueSerializer serializer = const ValueSerializer.defaults()}) {
     return {
-      'id': id,
-      'title': title,
-      'instructions': instructions,
-      'category': category,
+      'id': serializer.toJson<int>(id),
+      'title': serializer.toJson<String>(title),
+      'instructions': serializer.toJson<String>(instructions),
+      'category': serializer.toJson<int>(category),
     };
   }
 
@@ -295,19 +299,21 @@ class Ingredient extends DataClass {
           intType.mapFromDatabaseResponse(data['${effectivePrefix}calories']),
     );
   }
-  factory Ingredient.fromJson(Map<String, dynamic> json) {
+  factory Ingredient.fromJson(Map<String, dynamic> json,
+      {ValueSerializer serializer = const ValueSerializer.defaults()}) {
     return Ingredient(
-      id: json['id'] as int,
-      name: json['name'] as String,
-      caloriesPer100g: json['caloriesPer100g'] as int,
+      id: serializer.fromJson<int>(json['id']),
+      name: serializer.fromJson<String>(json['name']),
+      caloriesPer100g: serializer.fromJson<int>(json['caloriesPer100g']),
     );
   }
   @override
-  Map<String, dynamic> toJson() {
+  Map<String, dynamic> toJson(
+      {ValueSerializer serializer = const ValueSerializer.defaults()}) {
     return {
-      'id': id,
-      'name': name,
-      'caloriesPer100g': caloriesPer100g,
+      'id': serializer.toJson<int>(id),
+      'name': serializer.toJson<String>(name),
+      'caloriesPer100g': serializer.toJson<int>(caloriesPer100g),
     };
   }
 
@@ -433,19 +439,21 @@ class IngredientInRecipe extends DataClass {
           intType.mapFromDatabaseResponse(data['${effectivePrefix}amount']),
     );
   }
-  factory IngredientInRecipe.fromJson(Map<String, dynamic> json) {
+  factory IngredientInRecipe.fromJson(Map<String, dynamic> json,
+      {ValueSerializer serializer = const ValueSerializer.defaults()}) {
     return IngredientInRecipe(
-      recipe: json['recipe'] as int,
-      ingredient: json['ingredient'] as int,
-      amountInGrams: json['amountInGrams'] as int,
+      recipe: serializer.fromJson<int>(json['recipe']),
+      ingredient: serializer.fromJson<int>(json['ingredient']),
+      amountInGrams: serializer.fromJson<int>(json['amountInGrams']),
     );
   }
   @override
-  Map<String, dynamic> toJson() {
+  Map<String, dynamic> toJson(
+      {ValueSerializer serializer = const ValueSerializer.defaults()}) {
     return {
-      'recipe': recipe,
-      'ingredient': ingredient,
-      'amountInGrams': amountInGrams,
+      'recipe': serializer.toJson<int>(recipe),
+      'ingredient': serializer.toJson<int>(ingredient),
+      'amountInGrams': serializer.toJson<int>(amountInGrams),
     };
   }
 

moor/lib/src/runtime/data_class.dart

@@ -5,13 +5,14 @@ import 'dart:convert';
 abstract class DataClass {
   const DataClass();
 
-  // todo better docs, explain ValueSerializer
-
   /// Converts this object into a representation that can be encoded with
-  /// [json].
+  /// [json]. The [serializer] can be used to configure how individual values
+  /// will be encoded.
   Map<String, dynamic> toJson(
       {ValueSerializer serializer = const ValueSerializer.defaults()});
 
+  /// Converts this object into a json representation. The [serializer] can be
+  /// used to configure how individual values will be encoded.
   String toJsonString(
       {ValueSerializer serializer = const ValueSerializer.defaults()}) {
     return json.encode(toJson(serializer: serializer));
@@ -21,9 +22,17 @@ abstract class DataClass {
 /// Serializer responsible for mapping atomic types from and to json.
 abstract class ValueSerializer {
   const ValueSerializer();
+
+  /// The default serializer encodes date times as a unix-timestamp in
+  /// milliseconds.
   const factory ValueSerializer.defaults() = _DefaultValueSerializer;
 
+  /// Converts the [value] to something that can be passed to
+  /// [JsonCodec.encode].
   dynamic toJson<T>(T value);
+
+  /// Inverse of [toJson]: Converts a value obtained from [JsonCodec.decode]
+  /// into a value that can be hold by data classes.
   T fromJson<T>(dynamic json);
 }
 

moor/test/data/tables/todos.g.dart

@@ -33,23 +33,25 @@ class TodoEntry extends DataClass {
           intType.mapFromDatabaseResponse(data['${effectivePrefix}category']),
     );
   }
-  factory TodoEntry.fromJson(Map<String, dynamic> json) {
+  factory TodoEntry.fromJson(Map<String, dynamic> json,
+      {ValueSerializer serializer = const ValueSerializer.defaults()}) {
     return TodoEntry(
-      id: json['id'] as int,
-      title: json['title'] as String,
-      content: json['content'] as String,
-      targetDate: json['targetDate'] as DateTime,
-      category: json['category'] as int,
+      id: serializer.fromJson<int>(json['id']),
+      title: serializer.fromJson<String>(json['title']),
+      content: serializer.fromJson<String>(json['content']),
+      targetDate: serializer.fromJson<DateTime>(json['targetDate']),
+      category: serializer.fromJson<int>(json['category']),
     );
   }
   @override
-  Map<String, dynamic> toJson() {
+  Map<String, dynamic> toJson(
+      {ValueSerializer serializer = const ValueSerializer.defaults()}) {
     return {
-      'id': id,
-      'title': title,
-      'content': content,
-      'targetDate': targetDate,
-      'category': category,
+      'id': serializer.toJson<int>(id),
+      'title': serializer.toJson<String>(title),
+      'content': serializer.toJson<String>(content),
+      'targetDate': serializer.toJson<DateTime>(targetDate),
+      'category': serializer.toJson<int>(category),
     };
   }
 
@@ -215,17 +217,19 @@ class Category extends DataClass {
           stringType.mapFromDatabaseResponse(data['${effectivePrefix}desc']),
     );
   }
-  factory Category.fromJson(Map<String, dynamic> json) {
+  factory Category.fromJson(Map<String, dynamic> json,
+      {ValueSerializer serializer = const ValueSerializer.defaults()}) {
     return Category(
-      id: json['id'] as int,
-      description: json['description'] as String,
+      id: serializer.fromJson<int>(json['id']),
+      description: serializer.fromJson<String>(json['description']),
     );
   }
   @override
-  Map<String, dynamic> toJson() {
+  Map<String, dynamic> toJson(
+      {ValueSerializer serializer = const ValueSerializer.defaults()}) {
     return {
-      'id': id,
-      'description': description,
+      'id': serializer.toJson<int>(id),
+      'description': serializer.toJson<String>(description),
     };
   }
 
@@ -340,23 +344,25 @@ class User extends DataClass {
           .mapFromDatabaseResponse(data['${effectivePrefix}creation_time']),
     );
   }
-  factory User.fromJson(Map<String, dynamic> json) {
+  factory User.fromJson(Map<String, dynamic> json,
+      {ValueSerializer serializer = const ValueSerializer.defaults()}) {
     return User(
-      id: json['id'] as int,
-      name: json['name'] as String,
-      isAwesome: json['isAwesome'] as bool,
-      profilePicture: json['profilePicture'] as Uint8List,
-      creationTime: json['creationTime'] as DateTime,
+      id: serializer.fromJson<int>(json['id']),
+      name: serializer.fromJson<String>(json['name']),
+      isAwesome: serializer.fromJson<bool>(json['isAwesome']),
+      profilePicture: serializer.fromJson<Uint8List>(json['profilePicture']),
+      creationTime: serializer.fromJson<DateTime>(json['creationTime']),
     );
   }
   @override
-  Map<String, dynamic> toJson() {
+  Map<String, dynamic> toJson(
+      {ValueSerializer serializer = const ValueSerializer.defaults()}) {
     return {
-      'id': id,
-      'name': name,
-      'isAwesome': isAwesome,
-      'profilePicture': profilePicture,
-      'creationTime': creationTime,
+      'id': serializer.toJson<int>(id),
+      'name': serializer.toJson<String>(name),
+      'isAwesome': serializer.toJson<bool>(isAwesome),
+      'profilePicture': serializer.toJson<Uint8List>(profilePicture),
+      'creationTime': serializer.toJson<DateTime>(creationTime),
     };
   }
 
@@ -515,17 +521,19 @@ class SharedTodo extends DataClass {
       user: intType.mapFromDatabaseResponse(data['${effectivePrefix}user']),
     );
   }
-  factory SharedTodo.fromJson(Map<String, dynamic> json) {
+  factory SharedTodo.fromJson(Map<String, dynamic> json,
+      {ValueSerializer serializer = const ValueSerializer.defaults()}) {
     return SharedTodo(
-      todo: json['todo'] as int,
-      user: json['user'] as int,
+      todo: serializer.fromJson<int>(json['todo']),
+      user: serializer.fromJson<int>(json['user']),
     );
   }
   @override
-  Map<String, dynamic> toJson() {
+  Map<String, dynamic> toJson(
+      {ValueSerializer serializer = const ValueSerializer.defaults()}) {
     return {
-      'todo': todo,
-      'user': user,
+      'todo': serializer.toJson<int>(todo),
+      'user': serializer.toJson<int>(user),
     };
   }
 
@@ -632,17 +640,19 @@ class TableWithoutPKData extends DataClass {
           numType.mapFromDatabaseResponse(data['${effectivePrefix}some_float']),
     );
   }
-  factory TableWithoutPKData.fromJson(Map<String, dynamic> json) {
+  factory TableWithoutPKData.fromJson(Map<String, dynamic> json,
+      {ValueSerializer serializer = const ValueSerializer.defaults()}) {
     return TableWithoutPKData(
-      notReallyAnId: json['notReallyAnId'] as int,
-      someFloat: json['someFloat'] as num,
+      notReallyAnId: serializer.fromJson<int>(json['notReallyAnId']),
+      someFloat: serializer.fromJson<num>(json['someFloat']),
     );
   }
   @override
-  Map<String, dynamic> toJson() {
+  Map<String, dynamic> toJson(
+      {ValueSerializer serializer = const ValueSerializer.defaults()}) {
     return {
-      'notReallyAnId': notReallyAnId,
-      'someFloat': someFloat,
+      'notReallyAnId': serializer.toJson<int>(notReallyAnId),
+      'someFloat': serializer.toJson<num>(someFloat),
     };
   }
 

moor/tool/coverage.dart

@@ -8,27 +8,17 @@ import 'package:path/path.dart';
 
 import 'format_coverage.dart' as fc;
 
-const int _vmPort = 9876;
-
 Future<void> main(List<String> args) async {
   // First, generate the build script, see
   // https://github.com/dart-lang/build/blob/3208cfe94c475ed3e1ec44c227aadaddaeac263d/build_runner/bin/build_runner.dart#L65
   Pub.run('build_runner', arguments: ['generate-build-script']);
 
-  // Start coverage collection (resume isolates, don't wait for pause, collect
-  // when isolates exit).
-  final collectorFuture =
-      collect(Uri.parse('http://localhost:$_vmPort'), true, false, true);
-
   // Next, run the test script in another dart process that has the vm services
   // enabled.
   final tests = join(File.fromUri(Platform.script).parent.path, 'tester.dart');
-  // not using Dart.run because that only prints to stdout after the process has
-  // completed.
-  await Dart.runAsync(tests,
-      vmArgs: ['--enable-vm-service=$_vmPort', '--pause-isolates-on-exit']);
+  final coverage = await runAndCollect(tests, onExit: true, printOutput: true);
 
-  File('coverage.json').writeAsStringSync(json.encode(await collectorFuture));
+  File('coverage.json').writeAsStringSync(json.encode(coverage));
 
   print('formatting to .lcov format');
   await fc.main();

moor_generator/lib/src/writer/data_class_writer.dart

@@ -101,25 +101,34 @@ class DataClassWriter {
     final dataClassName = table.dartTypeName;
 
     buffer
-      ..write('factory $dataClassName.fromJson(Map<String, dynamic> json) {\n')
+      ..write('factory $dataClassName.fromJson('
+          'Map<String, dynamic> json,'
+          '{ValueSerializer serializer = const ValueSerializer.defaults()}'
+          ') {\n')
       ..write('return $dataClassName(');
 
     for (var column in table.columns) {
       final getter = column.dartGetterName;
       final type = column.dartTypeName;
 
-      buffer.write("$getter: json['$getter'] as $type,");
+      buffer.write("$getter: serializer.fromJson<$type>(json['$getter']),");
     }
 
     buffer.write(');}\n');
   }
 
   void _writeToJson(StringBuffer buffer) {
-    buffer.write('@override Map<String, dynamic> toJson() {\n return {');
+    buffer.write('@override Map<String, dynamic> toJson('
+        '{ValueSerializer serializer = const ValueSerializer.defaults()}) {'
+        '\n return {');
 
     for (var column in table.columns) {
-      final getter = column.dartGetterName;
-      buffer.write("'$getter': $getter,");
+      final name = column.dartGetterName;
+      final needsThis = name == 'serializer';
+      final value = needsThis ? 'this.$name' : name;
+
+      buffer
+          .write("'$name': serializer.toJson<${column.dartTypeName}>($value),");
     }
 
     buffer.write('};}');