I'm trying to create child by using transaction.
I did like so.
void _runTransaction(DatabaseReference ref, Map<String, dynamic> data) async {
await ref.runTransaction((MutableData tx) async {
tx.value = data;
return tx;
});
}
But app will crash and child won't be created.
Am I doing it wrong?
Does anyone have an idea what went wrong?
As document says
performs an optimistic-concurrency transactional update to the data at this
Firebase Database location.
I think you can't create with transaction.
After created the child, then update it with transaction worked.
Related
I have the following code piece in a function that I call when I need to fetch the user profile data.
FirebaseAuth _auth = FirebaseAuth.instance;
final FirebaseFirestore _firestore = FirebaseFirestore.instance;
Future getUserProfile() async {
try {
DocumentSnapshot ds =
await _firestore.collection('users').doc(_auth.currentUser.uid).get();
return ds;
} catch (e) {
print(e);
return null;
}
}
With the assumption that user's profile data does not change, does this call cost me 1 read each time I call the getUserProfile() function? If yes, how can I change this function so that my function only listens to changes and does not necessarily increase the number of reads in firestore?
Yes, each function call will cost you 1 read. If the data does not change through out the app you could fetch it at the start of your application and store it by creating a class say User, then add data to that User object. This method is very useful and would minimize the number of function calls made to fetch data.
Each time you call getUserProfile(), the read counter will increase by one.
Firestore offers an alternative to get() for listening to real time changes. It's called snapshots(), it returns a Stream<QuerySnapshot>. You can attach a listener and every time one of the documents you listen to, changes, it will be added to the stream. Initially all items matching your query (in your case it's only one) will be added to the stream. Your code should be then:
Stream<QuerySnapshot> getUserProfile() {
try {
Stream<QuerySnapshot> stream = _firestore
.collection('users')
.doc(_auth.currentUser.uid)
.snapshots();
return stream;
} catch (e) {
print(e);
return null;
}
}
Every time a change is added to the stream, the read will be increased by one.
More information can be found at the official Firestore Docs.
I'm running my integration-tests in flutter and dart using the firestore emulator. First I start the firestore emulator with some data like so: firebase emulators:start --import=./dir.
Then I start an android emulator and start the app I want to test on the android emulator. The app is configured to use the firestore emulator. Then I run a series of tests, which all write to the firestore emulator.
But on the beginning of each test, I want the data to be reset to the state, when I first started the emulator. So e.g. if the tests are executed in this order:
Test A
Test B
Test C
I don't want to have the data, Test A created to be present in the database, when Tests B and C are executed. I could terminate the firestore emulator and start it again at the beginning of each test. But this would make my tests a lot slower.
Do you know of a way to reset the data, which is present in the firebase emulator?
I am assuming you're referring to firestore when you say you want to 'reset the data'.
Per the documentation at https://firebase.google.com/docs/emulator-suite/install_and_configure#use_the_emulator_hub_rest_api
import fetch from 'node-fetch';
import firebaseConfig from '../../../firebase.json';
const hubEmulatorPort = firebaseConfig.emulators.hub.port;
const firestoreEmulatorPort = firebaseConfig.emulators.firestore.port;
async function clearDb() {
const response = await fetch(
`http://localhost:${firestoreEmulatorPort}/emulator/v1/projects/${process.env.PROJECT_ID}/databases/(default)/documents`,
{
method: 'DELETE',
}
);
if (response.status !== 200) {
throw new Error('Trouble clearing Emulator: ' + (await response.text()));
}
}
async function populateDb(data) {
// Logic for adding in any data you want in the db
// before each test run
}
async function enableBackgroundTriggers() {
const response = await fetch(`http://localhost:${hubEmulatorPort}/functions/enableBackgroundTriggers`, {
method: 'PUT',
});
if (response.status !== 200) {
throw new Error('Trouble enabling database triggers in emulator: ' + (await response.text()));
}
}
async function disableBackgroundTriggers() {
const response = await fetch(`http://localhost:${hubEmulatorPort}/functions/disableBackgroundTriggers`, {
method: 'PUT',
});
if (response.status !== 200) {
throw new Error('Trouble disabling database triggers in emulator: ' + (await response.text()));
}
}
async function resetDb(data) {
await disableBackgroundTriggers();
await clearDb();
await populateDb(data);
await enableBackgroundTriggers();
}
export { resetDb };
I can't find a source for the clearing of the db, but the RESTful call in clearDb does what you want.
It's important to disable the triggers before clearing or populating the database, in case you have firestore triggers that modify data in ways your tests don't expect. I write tests by passing full DB state to the populateDb method, then reenable triggers before running tests so I can test said triggers. If you aren't running any firestore triggers, the clearDb call alone should be enough for your purposes.
My tests all have calls to resetDb() in my beforeEach hook in jest to ensure clean runs of each test. I recommend adding this to whatever 'beforeEach'-like hook your favorite testing API exposes.
If your tests do things like create users in Firebase Authentication you'll have to find another way to clear them between test runs.
If anyone can find documentation on how to clear other emulators in the Firebase Emulator Suite, please drop it in the comments. I am currently trying to find a way to clear Authentication emulators, which is actually how I found this question.
Best of luck!
If you want to clear out all the collections programatically, like in a setUp() or tearDown() there's a reference for that here: Delete data from Cloud Firestore - Delete Collections
Note that it's not recommended for all implementations, but there are examples in Java, Python, Node.js, go, PHP, C#, and Ruby.
Here's an example of how to iterate through all your collections and delete them all in Java, using the deleteCollection() method from that link.
public static void main(String[] args) throws IOException {
final int BATCH_SIZE = 5;
Firestore firestore = initializeCloudFirestore();
for (CollectionReference listCollection : firestore.listCollections()) {
deleteCollection(listCollection, BATCH_SIZE);
}
}
/**
* One way of initializing Firestore,
* see other options at https://firebase.google.com/docs/firestore/quickstart#initialize
*/
private static Firestore initializeCloudFirestore() throws IOException {
// Use the application default credentials
GoogleCredentials credentials = GoogleCredentials.getApplicationDefault();
FirebaseOptions options = new FirebaseOptions.Builder()
.setCredentials(credentials)
.setProjectId("projectId")
.build();
FirebaseApp.initializeApp(options);
Firestore firestore = FirestoreClient.getFirestore();
return firestore;
}
/**
* Delete a collection in batches to avoid out-of-memory errors. Batch size may be tuned based on
* document size (atmost 1MB) and application requirements.
* See https://firebase.google.com/docs/firestore/manage-data/delete-data#java_5
*/
static void deleteCollection(CollectionReference collection, int batchSize) {
try {
// retrieve a small batch of documents to avoid out-of-memory errors
ApiFuture<QuerySnapshot> future = collection.limit(batchSize).get();
int deleted = 0;
// future.get() blocks on document retrieval
List<QueryDocumentSnapshot> documents = future.get().getDocuments();
for (QueryDocumentSnapshot document : documents) {
document.getReference().delete();
++deleted;
}
if (deleted >= batchSize) {
// retrieve and delete another batch
deleteCollection(collection, batchSize);
}
} catch (Exception e) {
System.err.println("Error deleting collection : " + e.getMessage());
}
}
For the entire file, including imports, see this Github Gist.
Using Flutter 1.20.2.
My Flutter app uses Firestore as it's backend database. For the current version I am using and throughout the development of this mobile app I have noticed that if my app is in the background for a period of time (could be a few mins) then when I bring the app back into the foreground the queries are very slow to return data. This does not happen on iOS. It only happens on Android.
I use CircularProgressIndicators when my app is busy retrieving data from Firestore. I am using a solid state management setup where each of my Views have a model that extends a BaseModel:
class BaseModel extends ChangeNotifier {
ViewState _state = ViewState.Idle;
ViewState get state => _state;
bool isDisposed = false;
void setState(ViewState viewState) {
_state = viewState;
if (!isDisposed) {
notifyListeners();
}
}
#override
void dispose() {
isDisposed = true;
super.dispose();
}
}
My views then use my view specific models in the following way:
#override
Widget build(BuildContext context) {
return BaseView<MyProfileModel>(
//onModelReady: (model) => model.initialise(Provider.of<User>(context, listen: false)),
onModelReady: (model) => model.initialise(),
builder: (context, model, child) => Scaffold(
resizeToAvoidBottomInset: false,
...
I do not use the AppLifecycleState class yet to do anything special when the app is in the background or is resumed from the background.
When my model is busy retrieving data I show busy circular progress indicators.
The issue is that when I resume my app from the background into the foreground, sometimes the app could be busy for up to 1 minute before it retrieves the data - but only the first time after being back in the foreground. All subsequent calls are normal. Sometimes, it even hangs on first attempt to get data after coming back to the foreground.
I feel like I am not implementing a best practice in relation to resuming an app into the foreground that uses the Firestore database. I have a suspicion that it has something to do with re-establishing the Firestore connection and/or local cache. My App uses the default settings for these.
All of my Firestore API calls are contained in it's own class and I call it the same way each time:
await Firestore.instance
.collection(DBStrings.COLLECTION_AD_MESSAGES)
.document(ad.adId)
.collection(DBStrings.COLLECTION_CHILD_AD_MESSAGES)
.document()
.setData({
// Set fields...
}).catchError((e) {
res = false;
});
Can someone give me some insight into this issue and what could be potentially causing it?
It seem to me that your app is loosing the connection and the data retrieved is from the cache. My suggestion is for you to try to change the backend data from the Firebase console while your app is in the background, then test to see if the retrieved data is the updated or the old one.
If the data is the old one, it means your app could not restore the connection. To overcome this problem you need to check the auth status (if used) and to check the connection status. A simple way to identify connection status and not allow the app to take a very long time before going cache, is to force the app to ask data from remote and provide a timeout, like this:
QuerySnapshot snapshot = await query.getDocuments(source: Source.server).timeout(
_timeoutDuration,
// this or any other callback to handle timeout
onTimeout: () => query.getDocuments(source: Source.cache));
If you are using auth, you can check the auth status by calling:
FirebaseUser currentUser = await _auth.currentUser();
if (currentUser != null) {
// Handle your auth problem here
}
If you are not using auth and the app is retrieving the data from the server after this long period, check if the app would come back faster without the firebase query.
I have many problems to read data from a simple Firebase DB and to store it.
It's the first time that I use it so any help will be appreciated.
The solution is Xamarin.Forms and this is the Android part, my main problem.
This is my DB Structure:
I need to read and write the "number" value stored.
I add all Firebase package like Firebase.Database and Firebase.Connection
In my Android Prj I have a class with these:
MainActivity.cs
private void InitFirebaseAuth()
{
var options = new FirebaseOptions.Builder()
.SetApplicationId("******")
.SetApiKey("*******")
.SetDatabaseUrl("******")
.Build();
if (app == null)
app = FirebaseApp.InitializeApp(this, options, "SaloneB");
}
FirebaseHelper.cs
DatabaseReference databaseReference;
FirebaseDatabase database
public void Connect()
{
database = FirebaseDatabase.GetInstance(MainActivity.app);
}
First I call Connect then I try something like this without result:
FirebaseClient firebase = new FirebaseClient("*****");
//This to retrieve value
var items = await firebase
.Child("number_of_user") //name of the table
.OnceAsync(); //retrieve the value
Items result is 0 elements
Thanks for help
I am using Firestore in flutter application. Each time user launch the application it retrieves some data from Firestore Cloud.
QuerySnapshot dataSnapshot = await Firestore.instance
.collection('/data')
.getDocuments();
When user opens the application on first time, it required from him to connect online, to get the data, and as Firebase documents say
For Android and iOS, offline persistence is enabled by default. To disable persistence, set the PersistenceEnabled option to false.
So, it should save the data that application have been read before to retrieve it while the device is offline; so user can access application at anytime with the same data that have been read.
The problem is: it takes too long time to retrieve the data while the device is offline, with the same codes and nothing changed!.
I tried to configure how much time it takes? On offline, it takes about 8 minutes and 40 seconds. But while on online, it takes just 10 seconds, maybe less.
So how can I solve this problem?
============
UPDATE
I manged to get more logs about this problem, which after take a lot of time, and will start application with the offline saved data, it prints this log
This typically indicates that your device does not have a healthy Internet connection at the moment. The client will operate in offline mode until it is able to successfully connect to the backend.
And then take 3 second for example (not much time) and continue with the next works.
I did open a new issue in GitHub too.
Is there a way to limit the time it takes?
And finally, with the help of diegoveloper comment in GitHub issue, I have reached the solution.
This comment
await Firestore.instance
.collection("Collection")
.getDocuments(source: source)
was a good solution if I decided to check source each time and then use it or I can use it in starting of a new Flutter project, but now I already have a lot of codes that need a better solution. So I decided to fork the cloud_firestore package and edit it.
You can find it here: https://github.com/ShadyBoshra2012/flutterfire/tree/master/packages/cloud_firestore
What I have edited:
firestore.dart
// The source of which the data will come from.
static Source _source = Source.serverAndCache;
static Source get source => _source;
Future<void> settings(
{bool persistenceEnabled,
String host,
bool sslEnabled,
bool timestampsInSnapshotsEnabled,
int cacheSizeBytes,
Source source}) async {
await channel.invokeMethod<void>('Firestore#settings', <String, dynamic>{
'app': app.name,
'persistenceEnabled': persistenceEnabled,
'host': host,
'sslEnabled': sslEnabled,
'timestampsInSnapshotsEnabled': timestampsInSnapshotsEnabled,
'cacheSizeBytes': cacheSizeBytes,
});
if (source != null) _source = source;
}
query.dart
source = Firestore.source; Line 92
document_reference.dart
source = Firestore.source; Line 83
How you can use it?
So you can use my forked repository in this way with using connectivity package from Google : https://pub.dev/packages/connectivity .
Add my forked repository in pubspec.yaml file
cloud_firestore:
git:
url: https://github.com/ShadyBoshra2012/flutterfire.git
path: packages/cloud_firestore
Then in your first screen or main
var connectivityResult = await (Connectivity().checkConnectivity());
if (connectivityResult == ConnectivityResult.none) {
await Firestore.instance.settings(source: Source.cache);
} else {
await Firestore.instance.settings(source: Source.serverAndCache);
}
and if you want to refresh the source when change the connection state:
StreamSubscription subscription;
void initState() {
super.initState();
// Check the internet connection after each change
// of the connection.
subscription = Connectivity()
.onConnectivityChanged
.listen((ConnectivityResult result) async {
// Check the internet connection and then choose the appropriate
// source for it.
var connectivityResult = await (Connectivity().checkConnectivity());
if (connectivityResult == ConnectivityResult.none) {
await Firestore.instance.settings(source: Source.cache);
} else {
await Firestore.instance.settings(source: Source.serverAndCache);
}
});
}
#override
void dispose() {
super.dispose();
subscription.cancel();
}
So I hope it works with everyone see it, and waiting for Flutter Team to code a better and better solution. Thanks for everyone has participated.
In addition to Shady Boshra's answer you can use FirebaseFirestore.instance.disableNetwork() functionality so your code will look like this:
StreamSubscription subscription;
void initState() {
super.initState();
// Check the internet connection after each change
// of the connection.
subscription = Connectivity()
.onConnectivityChanged
.listen((ConnectivityResult result) async {
// Check the internet connection and then choose the appropriate
// source for it.
var connectivityResult = await (Connectivity().checkConnectivity());
if (connectivityResult == ConnectivityResult.none) {
await FirebaseFirestore.instance.disableNetwork();
} else {
await FirebaseFirestore.instance.enableNetwork();
}
});
}