Flutter json map array of obejcts to class

Question

I would like to map the following json structure to models. I try to map the array to an List and than parse each set to model.

The following error would be displayed:

type 'MappedListIterable' is not a subtype of type 'List'

Json

  {
      "objectId": "vbbZIPV6qs",
      "sets": [
        {
          "repetitions": 10,
          "weight": 10,
          "time": 0
        }
      ],
      "description": "",
      "type": "EXERCISE",
    }

Flutter

class PlanItem {
  String type;
  String description;
  List<Set> sets = [];

  PlanItem(this.type, this.description, this.sets);

  factory PlanItem.fromJson(Map<String, dynamic> json) {
    return PlanItem(
      json['type'],
      json['description'],
      (json['sets'] as List).map((i) {
        return Set.fromJson(i);
      }).toList(),
    );
  }
}

class Set {
  int repetitions;
  int weight;
  int time;

  Set(this.repetitions, this.weight, this.time);

  // convert Json to an exercise object
  factory Set.fromJson(Map<String, dynamic> json) {
    return Set(
      json['repetitions'] as int,
      json['weight'] as int,
      json['time'] as int,
    );
  }
}

Error

Dinesh Balasubramanian · Accepted Answer · 2018-08-15 19:46:53Z

2

Your code perfectly works for me.

We will get this error if we miss toList() in below snippet,

(json['sets'] as List).map((i) {
    return Set.fromJson(i);
  }).toList(), // removing toList will get below error
// type 'MappedListIterable<Map<String, int>, Set>' is not a subtype of type 'List<Set>'

answered Aug 15, 2018 at 19:46

Dinesh Balasubramanian

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4 Comments

abuder Over a year ago

What version of flutter do you use? I use 0.5.1

Dinesh Balasubramanian Over a year ago

Same as yours. Dart VM version: 1.24.3

Dinesh Balasubramanian Over a year ago

Before this line class Set {, } is missing in above code (looks Set as inner class). As Dart doesn't allow inner class, it should be typo

abuder Over a year ago

Sorry, I will change code. The model looks so . gist.github.com/aBuder/ca09a5d08ede710e032f26dbaf45560a

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