Object Mapper

---

A package written in Dart that makes it easy for you to convert your model objects to and from JSON. It's inspired by ObjectMapper

object_mapper vs json_annotation

• No extras file (*.g.dart), no need to use builder_runner
• Re-usable Transform (known as Converter in json_annotation) with generic

Implement

• Step 1: Extend your class with Mappable mixin

class TestInfo with Mappable {
    //
}

• Step 2: Override Mappable.mapping method & add your map functions. Check more use cases here

class TestInfo with Mappable {
 int id;
  
 @override
 void mapping(Mapper map) {
  map("id", id, (v) => id = v);
 }
}

• Step 3: Register factory for new model into Mappable.factories

  Mappable.factories = {
    TestInfo: () => TestInfo()
  };
  

Usage

• Map to Object

final json = {
 "id" : 2
};

final info = Mapper.fromJson(json).toObject<TestInfo>();
print(info.id); // 2

• Object to Map

final info = TestInfo();
info.id = 2;
final json = info.toJson();
print(json); // { "id": 2 }

Map - Use Cases

• int, string, numeric, bool

void mapping(Mapper map) {
 map("field", field, (v) => field = v);
}

• List of number or bool

void mapping(Mapper map) {
 map("field", field, (v) => field = v.cast<int>());
}

• List of object or nested object

void mapping(Mapper map) {
 map<ObjectClass>("field", field, (v) => field = v);
}

• Nested json

void mapping(Mapper map) {
 map<ObjectClass>("field1.field2.field3", field, (v) => field = v);
}

• With transform, such as DateTransform, EnumTransform

DateTime time;
void mapping(Mapper map) {
 map("time", time, (v) => time = v, DateTransform());
}

Custom transform

Implement your class with Transformable

class EnumTransform<Object extends Enumerable, JSON>
    with Transformable<Object, JSON> {
  Object fromJson(value) {
    if (value == null || !(value is JSON)) return null;
    return RawRepresentable(Object, value);
  }

  JSON toJson(Object value) {
    if (value == null) return null;
    return value.rawValue;
  }
}