전제

dependencies:
  flutter:
    sdk: flutter
  firebase_core: "0.7.0"
  cloud_firestore: "^0.16.0+1"

문서의 필드란?

Firestore에서 문서 필드 얻기

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

// 省略

 fetchUserData() async {
    final FirebaseAuth _firebaseAuth = FirebaseAuth.instance;
    final FirebaseFirestore _firestore = FirebaseFirestore.instance;
    final userId = _firebaseAuth.currentUser.uid;
    DocumentSnapshot snapshot = await _firestore.doc('users/${userId}').get();
    print(snapshot.data()['email']);
    return snapshot.data();
  }

 @override
  Widget build(BuildContext context) {
// 省略
    TextButton(
      onPressed: fetchUserData, child: Text('取得！')),
}

print(snapshot.data());