Question 191002 in Flutter Question posted in
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Flutter – How to convert objects inside the array – JSON to Dart List with serialized model?

  var result = await httpCalls(....);

  List<UserModel> users = [];

  await result['users'].map((e) async {
    Map<String, dynamic> a = jsonDecode(jsonEncode(e));
    users.add(UserModel.fromJson(a));
  }).toList();

I am receiving an array of UserModel from the http calls. Currently, I am converting one by one to add it to the List<UserModel> users.

Is there better way to do this?

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2

Answers


  1. 0

    You can try this

    List<dynamic> parsedJson = jsonDecode("response here");
  List<UserModel> users = List<UserModel>.from(parsedJson.map<UserModel>((dynamic i) => UserModel.fromJson(i)));

    This will generate a list from the result of all UserModels

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  2. 0

    It’s not clear why you’ve added the async keyword in your lambda, nor why you encode and then decode each element.

    The important trick with List.map<T>() is to give it a generic type. This way it returns an iterable of the correct type and, in turn, the toList will give you the correct type.

      final list = (results['users'] as List<dynamic>)
      .map<UserModel>((elem) => UserModel.fromJson(elem))
      .toList();

    This takes the List<dynamic> you get from the decoded JSON (you can probably omit the as that I added for emphasis) and calls map. By typing the map, the compiler knows that the lambda must return a UserModel – so it will end up with an iterable of only user models, which can then be turned into a list of them. Thus the compiler knows that list is a List<UserModel>.

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