Map to Class in Dart

Question

Is there a standard way to convert a map to an object of a user defined class?

In Python you can do MyClass(**map) which basically unwraps the map into named argumen

Answer 1

You can use Function.apply. I made a gist to test it out the linked answer

Answer 2

There is no built-in way.
You can use one of the serialization packages like

• https://pub.dev/packages/json_serializable
• https://pub.dev/packages/built_value
• ...

Answer 3

With this approach, the calling code can have type safety, autocompletion for the street and city fields, and compile-time exceptions. If you make typos or treat the fields as ints instead of Strings, the app won’t compile, instead of crashing at runtime.

A Address.fromJson() constructor, for constructing a new User instance from a map structure.

A toJson() method, which converts a User instance into a map.

class Address {
  String street;
  String city;

  Address(this.street, this.city);

  Address.fromJson(Map<String, dynamic> json)
      : street = json['street'],
        city = json['city'];

  Map<String, dynamic> toJson() =>
      {
        'citstreety': street,
        'city': city,
      };
}


List<Address>  getAddressList(){

  Map myMap = {"address": [
    {"street": "Marine Lines", "city": "Mumbai"},
    {"street": "Main Road", "city": "Delhi"},
  ]
  };

  var data = myMap["address"];
  List<Address> addressModelList = [];
  for (var u in data) {
    Address address =
    Address.fromJson(u);
    addressModelList.add(address);
  }
  return addressModelList;
}

Answer 4

You can also achieve this manually by using named constructor like this simple example:

import 'package:flutter/material.dart';

Map myMap = {"Users": [

  {"Name": "Mark", "Email": "mark@email"},


  {"Name": "Rick", "Email": "rick@email"},
]
};

class MyData {
  String name;
  String email;

  MyData.fromJson(Map json){
    this.name = json["Name"];
    this.email = json ["Email"];
  }
}

class UserList extends StatelessWidget {
  MyData data;

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
        appBar: new AppBar(title: new Text("User List"),),
        body:
        new ListView.builder(
            shrinkWrap: true,
            itemCount: myMap["Users"].length,
            itemBuilder: (BuildContext context, int index) {
              data = new MyData.fromJson(myMap["Users"][index]);
              return new Text("${data.name} ${data.email}");
            })
    );
  }
}