Flutter How to convert List into and from JSON

Question

There are two Functions that I use to convert two String variables into JSON and from JSON.

String toJson() {
  Map<String,dynamic> map = {'name': name,'count':checkListCount,'description':description,};
  return jsonEncode(map)
}

fromJson(String context){
  Map<String,dynamic> map = jsonDecode(contents)
  name = map['name'];
  description = map['description'];
  return '0';
}

How i can use this to functions to covert List? There is my list

List<CheckListPoint> checkListPoints = [];

CheckListPoint{
  bool correctly = false;
  bool passed = false;
  String requirement = '';
}

variables that I have in CheckListPoint will change by the user later in the app.

Follow this tutorial about serialization in flutter: flutter.dev/docs/development/data-and-backend/json — Omar Fayad
– Omar Fayad, Commented Aug 17, 2021 at 10:04

Vaidehee Vala · Accepted Answer · 2021-08-17 11:10:10Z

1

i am not exactly getting which key will give you the list of data from your question, but suppose you have a response in with "data" key is giving you list of items, then you can add from JSON with ->

    data : List<User>.from(json["data"].map((x) => User.fromJson(x))),

and to convert it to JSON you need

    "data": List<dynamic>.from(data.map((x) => x.toJson())),

i hope this is what you are asking for

answered Aug 17, 2021 at 11:10

Vaidehee Vala

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Comments

Berke Alp · Accepted Answer · 2021-08-17 11:19:28Z

I did a very similiar thing when fetching messages from firebase. It's the same as parsing from JSON since both values are dynamic.

Here I convert a DataSnapshot to a List

Future<List<Message>> getMessages(DataSnapshot snapshot) async {
    List<Message> msgs = List.empty(growable: true);
    if(snapshot.value != null) {
      Map<dynamic, dynamic> messages = snapshot.value;
      messages.forEach((key, value) {
        msgs.add(Message.fromFirebase(value));
      });
    }
    return msgs;
 }

And here is the Message class:

class Message {
  String message;
  String senderId;
  int time;

  Message.fromFirebase(Map<dynamic, dynamic> json) :
      message = json["message"],
      senderId = json["senderId"],
      time = json["time"];
}

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