Get all from a Firestore collection in Flutter

This is the easiest way to get all data from collection that I found working, without using deprecated methods.

CollectionReference _collectionRef =
    FirebaseFirestore.instance.collection('collection');

Future<void> getData() async {
    // Get docs from collection reference
    QuerySnapshot querySnapshot = await _collectionRef.get();

    // Get data from docs and convert map to List
    final allData = querySnapshot.docs.map((doc) => doc.data()).toList();

    print(allData);
}

I was able to figure out a solution:

Future getDocs() async {
  QuerySnapshot querySnapshot = await Firestore.instance.collection("collection").getDocuments();
  for (int i = 0; i < querySnapshot.documents.length; i++) {
    var a = querySnapshot.documents[i];
    print(a.documentID);
  }
}

Call the getDocs() function, I used build function, and it printed all the document IDs in the console.

Using StreamBuilder

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

class ExpenseList extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new StreamBuilder<QuerySnapshot>(
        stream: Firestore.instance.collection("expenses").snapshots,
        builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
          if (!snapshot.hasData) return new Text("There is no expense");
          return new ListView(children: getExpenseItems(snapshot));
        });
  }

  getExpenseItems(AsyncSnapshot<QuerySnapshot> snapshot) {
    return snapshot.data.documents
        .map((doc) => new ListTile(title: new Text(doc["name"]), subtitle: new Text(doc["amount"].toString())))
        .toList();
  }
}

Here is the code if you just want to read it once

   QuerySnapshot querySnapshot = await Firestore.instance.collection("collection").getDocuments();
    var list = querySnapshot.documents;