How can I map an object to different type of object in flutter dart?

Question

Is there any way to map an object for instance PersonModel to PersonEntity in flutter dart?

Solution 1

This is how I currently do that kind of mapping, first I declare an interface (abstracted class) for the mapper:

abstract class Mapper<FROM, TO> {
  TO call(FROM object);
}

Then, I make the custom mapper for any models, entities like so:

class ToSource implements Mapper<SourceModel, Source> {
  @override
  Source call(SourceModel object) {
    return Source(
      id: object.id,
      name: object.name,
    );
  }
}

And The usage would be like this: (mapping SourceModel class to Source class)

final toSourceMapper = ToSource();

final sourceModel = SourceModel(id: 'f4sge248f3', name: 'bbc news');
final source = toSourceMapper(sourceModel);

If there is another better way of doing such thing, answer below.. it would be helpful for all.

Solution 2

Simplest way:

void main() {
  final model = PersonModel(id: 0, name: 'name0');
  final entity = _convert(model);
  print(entity);
}

final _convert = (PersonModel e) => PersonEntity(
      id: e.id,
      name: e.name,
    );

class PersonEntity {
  int id;
  String name;
  PersonEntity({this.id, this.name});

  @override
  String toString() => 'id: $id, name: $name';
}

class PersonModel {
  int id;
  String name;
  PersonModel({this.id, this.name});
}

Result:

id: 0, name: name0

Comments

[pskink]

yes, it is possible

[devmuaz]

@pskink how? could you explain more?

[devmuaz]

@pskink it would be helpful if there is a library or package for code generation to automatically setting the objects and types then map to what ever..

[pskink]

i dont think there is such library: you need to do that by yourself

[devmuaz]

@pskink this is how I currently do it, see first answer by me.

[jamesdlin]

It's not clear why you bother with the Mapper and ToSource classes when you could just define a freestanding Source toSourceMapper(SourceModel object) function.

[devmuaz]

@jamesdlin it should be part of separation process in the clean architecture, so I need to have a clear way to map different objects from/to different data layers.

[jamesdlin]

It adds obfuscation, and I see no advantage. You'd still need separate ToXXX classes for each combination of types; you might as well just have separately named functions. Perhaps you could provide an example where the classes provide some benefit.

[EngineSense]

how to convert List<Object> to List<ObjectEntity> ?

[mezoni]

@EngineSense You should ask new question.

[Hunt]

@jamesdlin so if i have the neasted classes then do i need to map them field by field? is there any library that does the task ?

[jamesdlin]

@Hunt Huh? I don't understand what you're asking or what it has to do with classes vs. functions. Also, Dart doesn't support nested classes.

[devmuaz]

@EngineSense use list.map function to do that