Save list getting from JSON URL in firestore collection

Question

My small app, is getting list of users from JSON link then store it in the List, I wanna this list into usersCollection collection ref of firestore

my code

import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:fluttertoast/fluttertoast.dart';
import 'dart:async';
import 'package:http/http.dart' as http;
import 'package:yat_flutter_app/main.dart';
import 'usersList.dart';
import 'package:cloud_firestore/cloud_firestore.dart';

class MyApp extends StatefulWidget {

  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {

  CollectionReference usersCollection =
  FirebaseFirestore.instance.collection('users');

  Future<List<User>> getUsers() async {
    var data = await http
        .get("https://www.json-generator.com/api/json/get/bYKKPeXRcO?indent=2");
    var jasonData = json.decode(data.body);
    List<User> users = [];

    for (var i in jasonData) {
      User user = User(i["index"], i["about"], i["name"], i["picture"],
          i["company"], i["email"]);
      users.add(user);
    }

    return users;
  }


  @override
  Widget build(BuildContext context) {

    List<User> usersList = getUsers() as List<User>;


    return Container(

      child: Column(
        children: [
          FutureBuilder(
            future: getUsers(),
            builder: (BuildContext context, AsyncSnapshot asyncSnapshop) {
              if (asyncSnapshop.hasData) {
                return Expanded(
                  child: ListView.builder(
                      shrinkWrap: true,
                      itemCount: asyncSnapshop.data.length,
                      itemBuilder: (BuildContext context, int index) {
                        return Card(
                          elevation: 5,
                          color: Colors.cyan[50],
                          child: ListTile(
                            trailing: Icon(Icons.share),
                            title: Text(asyncSnapshop.data[index].name, style: TextStyle(fontFamily: 'Tahoma',fontSize: 20,fontWeight: FontWeight.bold),),
                            leading: CircleAvatar(
                              backgroundImage: NetworkImage(
                                  asyncSnapshop.data[index].picture +
                                      asyncSnapshop.data[index].index.toString() +
                                      ".jpg"),
                            ),
                            subtitle: Text(asyncSnapshop.data[index].email,style: TextStyle(fontFamily: 'Tahmoma',fontSize: 18),),
                            onTap: (){
                              Navigator.push(context, new MaterialPageRoute(builder: (context)=>
                                  detailsPage(asyncSnapshop.data[index])
                              ));
                            },

                            onLongPress: ()=>

                                Fluttertoast.showToast(
                                    msg: asyncSnapshop.data[index].name,
                                    toastLength: Toast.LENGTH_SHORT,
                                    gravity: ToastGravity.CENTER,
                                    timeInSecForIosWeb: 1,
                                    backgroundColor: Colors.green[900],
                                    textColor: Colors.white,
                                    fontSize: 16.0
                                ),

                          ),
                        );
                      }),
                );
              } else {
                return Text("Loading, please wait...");
              }
            },
          ),

          ElevatedButton(
              child: Text('Save data'),
              onPressed: () => {
                
      usersCollection.add(getUsers()); // here's I am trying to add the result of getUsers into usersCollection 

              }),
        ],

      ),
    );
  }
}

Answer 1

To push this list to Firestore you need to fromJson and toJson methods in your model class

 factory User.fromJson(Map<String, dynamic> data){
    return User(
        index: data['index'] as int,
        about: data['about'] as String,
        name: data['name'] as String,
        picture: data['picture'] as String,
        company: data['company'] as String,
        email: data['email'] as String );
  }

  Map<String, dynamic> toJson(){

    return {
        "index": index,
        "about" : about,
        "name" : name,
        "picture" : picture,
        "company" : company,
        "email" : email,
    };
  }

instead that I would like to suggest using json_serializable library

then you need to do some changes in your future method like this

getUsers().then((users) {
// add users to map
});

and then you can use fromJson method to push it to firestore database

Answer 2

To push an object to Firestore you need to convert your object to map.
You can just add this function to your class:

  Map<String, dynamic> toMap() {
    return {
      'field1': value1,
      'field2': value1,
    };
  }

To push a List , you need to convert all objects to map, you can do it with following method:

  static List<Map> ConvertToMap({List myList }) {
    List<Map> steps = [];
    myList.forEach((var value) {
      Map step = value.toMap();
      steps.add(step);
    });
    return steps;
  }

Or simply , see how to convert List to Map

I hope it will be useful