Flip the option name and default

Author: kevmoo

json_serializable/README.md

@@ -83,14 +83,14 @@ targets:
           # Options configure how source code is generated for every
           # `@JsonSerializable`-annotated class in the package.
           #
-          # The default value for each of them: `false`.
+          # The default value for each is shown.
           #
           # For usage information, reference the corresponding field in
           # `JsonSerializableGenerator`.
-          use_wrappers: true
-          any_map: true
-          checked: true
-          explicit_to_json: true
+          use_wrappers: false
+          any_map: false
+          checked: false
+          implicit_to_json: true
 ```
 
 [example]: https://github.com/dart-lang/json_serializable/blob/master/example

json_serializable/lib/builder.dart

@@ -30,7 +30,7 @@ Builder jsonSerializable(BuilderOptions options) {
     useWrappers: optionsMap.remove('use_wrappers') as bool,
     checked: optionsMap.remove('checked') as bool,
     anyMap: optionsMap.remove('any_map') as bool,
-    explicitToJson: optionsMap.remove('explicit_to_json') as bool,
+    implicitToJson: optionsMap.remove('implicit_to_json') as bool,
   );
 
   if (optionsMap.isNotEmpty) {

json_serializable/lib/src/json_part_builder.dart

@@ -26,14 +26,14 @@ Builder jsonPartBuilder({
   bool useWrappers: false,
   bool anyMap: false,
   bool checked: false,
-  bool explicitToJson: false,
+  bool implicitToJson: true,
 }) {
   return new PartBuilder([
     new JsonSerializableGenerator(
       useWrappers: useWrappers,
       anyMap: anyMap,
       checked: checked,
-      explicitToJson: explicitToJson,
+      implicitToJson: implicitToJson,
     ),
     const JsonLiteralGenerator()
   ], header: header, formatOutput: formatOutput);

json_serializable/lib/src/json_serializable_generator.dart

@@ -66,25 +66,25 @@ class JsonSerializableGenerator
   /// [CheckedFromJsonException] is thrown.
   final bool checked;
 
-  /// If `true`, generated `toJson` methods will explicitly call `toJson` on
+  /// If `false`, generated `toJson` methods will explicitly call `toJson` on
   /// nested objects.
   ///
   /// When using JSON encoding support in `dart:convert`, `toJson` is
   /// automatically called on objects, so the default behavior
-  /// (`explicitToJson: false`) is to omit the `toJson` call.
+  /// (`implicitToJson: true`) is to omit the `toJson` call.
   ///
-  /// Example of `explicitToJson: false` (default)
+  /// Example of `implicitToJson: true` (default)
   ///
   /// ```dart
   /// Map<String, dynamic> toJson() => {'child': child};
   /// ```
   ///
-  /// Example of `explicitToJson: true`
+  /// Example of `implicitToJson: false`
   ///
   /// ```dart
   /// Map<String, dynamic> toJson() => {'child': child?.toJson()};
   /// ```
-  final bool explicitToJson;
+  final bool implicitToJson;
 
   /// Creates an instance of [JsonSerializableGenerator].
   ///
@@ -95,11 +95,11 @@ class JsonSerializableGenerator
     bool useWrappers: false,
     bool anyMap: false,
     bool checked: false,
-    bool explicitToJson: false,
+    bool implicitToJson: true,
   })  : this.useWrappers = useWrappers ?? false,
         this.anyMap = anyMap ?? false,
         this.checked = checked ?? false,
-        this.explicitToJson = explicitToJson ?? false,
+        this.implicitToJson = implicitToJson ?? true,
         this._typeHelpers = typeHelpers ?? _defaultHelpers;
 
   /// Creates an instance of [JsonSerializableGenerator].

json_serializable/lib/src/type_helper_context.dart

@@ -28,7 +28,7 @@ class TypeHelperContext implements SerializeContext, DeserializeContext {
   // Consider exposing it if there is interest
   bool get anyMap => _generator.anyMap;
 
-  bool get explicitToJson => _generator.explicitToJson;
+  bool get implicitToJson => _generator.implicitToJson;
 
   TypeHelperContext(this._generator, this.metadata, this.nullable,
       this.fromJsonData, this.toJsonData);

json_serializable/lib/src/type_helpers/json_helper.dart

@@ -16,21 +16,24 @@ import '../utils.dart';
 class JsonHelper extends TypeHelper {
   const JsonHelper();
 
-  /// Simply returns the [expression] provided.
+  /// If the builder is configured with `implicit_to_json: true`, simply returns
+  /// the [expression] provided.
   ///
-  /// By default, JSON encoding in from `dart:convert` calls `toJson()` on
-  /// provided objects.
+  /// Otherwise, returns [expression]`.toJson()` with proper `null` handling.
   @override
   String serialize(
       DartType targetType, String expression, SerializeContext context) {
     if (!_canSerialize(targetType)) {
       return null;
     }
 
-    if (context is TypeHelperContext && context.explicitToJson) {
-      return '$expression${context.nullable ? '?' : ''}.toJson()';
+    var ctx = context as TypeHelperContext;
+
+    if (ctx.implicitToJson) {
+      return expression;
     }
-    return expression;
+
+    return '$expression${context.nullable ? '?' : ''}.toJson()';
   }
 
   @override

json_serializable/test/config_test.dart

@@ -101,13 +101,13 @@ const _validConfig = const {
   'use_wrappers': true,
   'any_map': true,
   'checked': true,
-  'explicit_to_json': true
+  'implicit_to_json': false
 };
 
 const _invalidConfig = const {
   'header': true,
   'use_wrappers': 42,
   'any_map': 42,
   'checked': 42,
-  'explicit_to_json': 42
+  'implicit_to_json': 42
 };

json_serializable/test/json_serializable_test.dart

@@ -70,7 +70,7 @@ void _registerTests(JsonSerializableGenerator generator) {
     test('nullable', () async {
       var output = await _runForElementNamed(
           new JsonSerializableGenerator(
-              explicitToJson: true, useWrappers: generator.useWrappers),
+              implicitToJson: false, useWrappers: generator.useWrappers),
           'TrivialNestedNullable');
 
       var expected = generator.useWrappers
@@ -115,7 +115,7 @@ class _$TrivialNestedNullableJsonMapWrapper extends $JsonMapWrapper {
     test('non-nullable', () async {
       var output = await _runForElementNamed(
           new JsonSerializableGenerator(
-              explicitToJson: true, useWrappers: generator.useWrappers),
+              implicitToJson: false, useWrappers: generator.useWrappers),
           'TrivialNestedNonNullable');
 
       var expected = generator.useWrappers