how to get data from firebase in flutter - firebase

Question

I am building a flutter app and using cloud-firestore,
this is how my database looks like
I want a function that retrieves all documents in the collection called "Driver List" in an array of strings
that what I had already used but it gets them back in a listview in a new screen
class DriverList extends StatelessWidget {#overrideWidget build(BuildContext context) {
return new StreamBuilder<QuerySnapshot>(
stream: Firestore.instance.collection('DriverList').snapshots(),
builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
if (!snapshot.hasData) return new Text('Loading...');
return new ListView(
children: snapshot.data.documents.map((DocumentSnapshot document) {
return new ListTile(
title: new Text(document['name']),
subtitle: new Text(document['phone']),
);
}).toList(),
);
},
);
}
}

Answer 1

This has some additional logic to remove potentially duplicate records, but you can use something like the following to retrieve data from Firestore.
We get access to a collection reference, then list the results of the query, then create local model objects for the data returned by Firestore, and then we return the a list of those model objects.
static Future<List<AustinFeedsMeEvent>> _getEventsFromFirestore() async {
CollectionReference ref = Firestore.instance.collection('events');
QuerySnapshot eventsQuery = await ref
.where("time", isGreaterThan: new DateTime.now().millisecondsSinceEpoch)
.where("food", isEqualTo: true)
.getDocuments();
HashMap<String, AustinFeedsMeEvent> eventsHashMap = new HashMap<String, AustinFeedsMeEvent>();
eventsQuery.documents.forEach((document) {
eventsHashMap.putIfAbsent(document['id'], () => new AustinFeedsMeEvent(
name: document['name'],
time: document['time'],
description: document['description'],
url: document['event_url'],
photoUrl: _getEventPhotoUrl(document['group']),
latLng: _getLatLng(document)));
});
return eventsHashMap.values.toList();
}
Source: https://github.com/dazza5000/austin-feeds-me-flutter/blob/master/lib/data/events_repository.dart#L33

Answer 2

Getting one time data:
var collection = FirebaseFirestore.instance.collection('DriverList');
var querySnapshot = await collection.get();
for (var queryDocumentSnapshot in querySnapshot.docs) {
Map<String, dynamic> data = queryDocumentSnapshot.data();
var name = data['name'];
var phone = data['phone'];
}
Getting data each time it changes, using a StreamBuilder:
StreamBuilder<QuerySnapshot<Map<String, dynamic>>>(
stream: FirebaseFirestore.instance.collection('DriverList').snapshots(),
builder: (_, snapshot) {
if (snapshot.hasError) return Text('Error = ${snapshot.error}');
if (snapshot.hasData) {
final docs = snapshot.data!.docs;
return ListView.builder(
itemCount: docs.length,
itemBuilder: (_, i) {
final data = docs[i].data();
return ListTile(
title: Text(data['name']),
subtitle: Text(data['phone']),
);
},
);
}
return Center(child: CircularProgressIndicator());
},
)

Answer 3

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';
class LoadDataFromFirestore extends StatefulWidget {
#override
_LoadDataFromFirestoreState createState() => _LoadDataFromFirestoreState();
}
class _LoadDataFromFirestoreState extends State<LoadDataFromFirestore> {
#override
void initState() {
super.initState();
getDriversList().then((results) {
setState(() {
querySnapshot = results;
});
});
}
QuerySnapshot querySnapshot;
#override
Widget build(BuildContext context) {
return Scaffold(
body: _showDrivers(),
);
}
//build widget as prefered
//i'll be using a listview.builder
Widget _showDrivers() {
//check if querysnapshot is null
if (querySnapshot != null) {
return ListView.builder(
primary: false,
itemCount: querySnapshot.documents.length,
padding: EdgeInsets.all(12),
itemBuilder: (context, i) {
return Column(
children: <Widget>[
//load data into widgets
Text("${querySnapshot.documents[i].data['activation']}"),
Text("${querySnapshot.documents[i].data['car1']}"),
Text("${querySnapshot.documents[i].data['car2']}"),
Text("${querySnapshot.documents[i].data['car5']}"),
Text("${querySnapshot.documents[i].data['name']}"),
Text("${querySnapshot.documents[i].data['phone']}"),
],
);
},
);
} else {
return Center(
child: CircularProgressIndicator(),
);
}
}
//get firestore instance
getDriversList() async {
return await Firestore.instance.collection('DriversList').getDocuments();
}
}

Answer 4

body: SafeArea(
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
StreamBuilder(
stream:
FirebaseFirestore.instance.collection('messages').snapshots(),
builder: (context, snapshot) {
if (snapshot.hasError) {
return Center(
child: Text(snapshot.error.toString()),
);
}
if (snapshot.hasData) {
final messages = snapshot.data!.docs;
List<Text> messageWigdets = [];
for (var message in messages) {
final messageText = message['text'];
final messageSender = message['sender'];
final messageWigdet =
Text('$messageText from $messageSender');
messageWigdets.add(messageWigdet);
}
return Expanded(
child: ListView(
children: [...messageWigdets],
),
);
}
return const CircularProgressIndicator.adaptive();
},
),