Firebase Documentsnapshot map to Json object in Flutter

2
votes

I am trying to map a DocumentSnap from Firebase to a Json Class in Flutter. I can confirm that my is getting the data from the document, but i cannot pass the gathered data to my Json object. I have attached code and error message.

Class for getting the document from Firebase DatabaseService.dart

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_auth/firebase_auth.dart';

import 'package:oast_app/widgets/auth_class.dart';



class FireTest {
  Future<List<UserCheck>> streamUser(FirebaseUser user) async {
    DocumentSnapshot querySnapshot =
        await Firestore.instance.collection('users').document(user.uid).get();
    if (querySnapshot.exists) {
      print('success');
      print(querySnapshot.data['fname']);
      print(querySnapshot.data['lname']);

      querySnapshot.data.map<String, dynamic>((json) => UserCheck.fromJson(json)); **this is whats erroring**
    }
    return [];
  }
}

Json Object class

import 'package:flutter/material.dart';
import 'package:json_annotation/json_annotation.dart';

part 'auth_class.g.dart';

@JsonSerializable(nullable: false)
class UserCheck extends ChangeNotifier {
  final String uid;
  final String fName;
  final String lName;
  final String regEmail;
  final String org;

  UserCheck({
    this.uid,
    this.fName,
    this.lName,
    this.regEmail,
    this.org,
  });

  factory UserCheck.fromJson(Map<String, dynamic> json) =>
      _$UserCheckFromJson(json);

  Map<String, dynamic> toJson() => _$UserCheckToJson(this);
}

Error Message

Compiler message: lib/widgets/database_service.dart:17:76: Error: The argument type 'String' can't be assigned to the parameter type 'Map'. - 'Map' is from 'dart:core'. querySnapshot.data.map((json) => UserCheck.fromJson(json)); ^ lib/widgets/database_service.dart:17:67: Error: A value of type 'UserCheck' can't be assigned to a variable of type 'MapEntry'. - 'UserCheck' is from 'package:oast_app/widgets/auth_class.dart' ('lib/widgets/auth_class.dart'). - 'MapEntry' is from 'dart:core'. querySnapshot.data.map((json) => UserCheck.fromJson(json)); ^ lib/widgets/database_service.dart:17:47: Error: The argument type 'MapEntry Function(String)' can't be assigned to the parameter type 'MapEntry Function(String, dynamic)'. - 'MapEntry' is from 'dart:core'. querySnapshot.data.map((json) => UserCheck.fromJson(json));

firebase structure enter image description here ^ collection('users').document('user.uid') this is the document im trying to get

2
firebasefluttergoogle-cloud-firestorejsonserializer
do you want to convert documentsnapshot to data class right? – BloodLoss
Yes, what’s in my UserCheck class which is for Json – David Escobar
Instead of using map operation, use 'for each'. querySnapshot.data.forEach((json) => UserCheck.fromJson(json)); – Alvindrakes
@Alvindrakes made the change, new error, Compiler message: lib/widgets/database_service.dart:16:63: Error: The argument type 'String' can't be assigned to the parameter type 'Map<String, dynamic>'. - 'Map' is from 'dart:core'. querySnapshot.data.forEach((json) => UserCheck.fromJson(json)); – David Escobar
Could you edit your question with a screenshot of your firestore data structure, that way it would be easier for us to understand the incoming data. – Alvindrakes

2 Answers

2
votes

Assuming that you have the collection name as "tblcustomers",

Stream<QuerySnapshot> stream = _db.collection("tblcustomers").snapshots();
  jsonObject = Customers(error: false, errorCode: 0, Items: List<Customers_items>());
  stream.forEach((QuerySnapshot element) {
    if (element == null) return;

    setState(() {
      jsonObject.Items = element.documents.map((e) => Customers_items.fromJson(e.data)).toList();
    });
  });
0
votes

Your target type that you set at the map has to be the type that you want as result of the map.

So it should be

querySnapshot.data.map((json) => UserCheck.fromJson(json)).toList();