Flutter constructor from json list-string

Question

Hi I cant solve my error.

E/flutter (30343): [ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled Exception: type 'List' is not a subtype of type 'List'

class Exercise {
  int id;
  String name;
  List<int> equipmentIds;

  Exercise(this.id, this.name, this.equipmentIds);

  Exercise.fromJson(Map<String, dynamic> json)
      : id = json['id'],
        name = json['name'],
        equipmentIds = json['equipmentIds'];

  Map<String, dynamic> toJson() =>
      {'id': id, 'name': name, 'equipmentIds': equipmentIds};
}

could you include your api response too?

eamirho3ein
– eamirho3ein

2022-10-29 10:06:40 +00:00
Commented Oct 29, 2022 at 10:06 — eamirho3ein
– eamirho3ein, Commented Oct 29, 2022 at 10:06
can you please add the json string you receive as code?

Zahra
– Zahra

2022-10-29 10:06:59 +00:00
Commented Oct 29, 2022 at 10:06 — Zahra
– Zahra, Commented Oct 29, 2022 at 10:06

Md. Yeasin Sheikh · Accepted Answer · 2022-10-29 10:07:56Z

1

You can use List.from

return Exercise(
  map['id']?.toInt() ?? 0,
  map['name'] ?? '',
  List<int>.from(map['equipmentIds']),
);

It would better to handle null while reading map , can be List<int>.from(map['equipmentIds']?? [] ),

answered Oct 29, 2022 at 10:07

Md. Yeasin Sheikh

64.8k7 gold badges50 silver badges86 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Franz Over a year ago

Worked with equipmentIds = List<int>.from(json['equipmentIds']); My List is not nullable so I always just pass an empty list [].

Collectives™ on Stack Overflow

Flutter constructor from json list-string

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related