I use Google Firestore for my iOS app built in Swift/SwiftUI and would like to implement the Snapshot listeners feature to my app.
I want to list all documents in debts collection in realtime by using snapshot listeners. Every document in this collection has subcollection debtors, which I want to get in realtime for each debts document as well. Each document in debtors has field userId, which refers to DocumentID in users collection which I would also love to have realtime connection on (for example when user changes his name I would love to see it instantly in the debt entity inside the list). This means I must initialize 2 more snapshot listeners for each document in debts collection. I'm concerned that this is too many opened connections once I have like 100 debts in the list. I can't come up with no idea apart from doing just one time fetches.
Have anyone of you ever dealt with this kind of nested snapshot listeners? Do I have a reason to worry?
This is my Firestore db
Debts
document
- description
- ...
- debtors (subcollection)
- userId
- amount
- ...
Users
document
- name
- profileImage
- email
I uploaded this gist where you can see how I operate with Firestore right now.
https://gist.github.com/michalpuchmertl/6a205a66643c664c46681dc237e0fb5d
If you want to read all debtors documents anywhere in the database with a given value for userId, you can use a collection group query to do so.
In Swift that'd look like:
db.collectionGroup("debtors").whereField("userId", isEqualTo: "uidOfTheUser").getDocuments { (snapshot, error) in
// ...
}
This will read from any collection name debtors. You'll have to add the index for this yourself, and set up the proper security rules. Both of those are documented in the link I included above.
Related
I have a nested collection in firestore that I want to make a query from it.
As you can see the first collection called 'businessUsers' and the nested one called 'campaigns',
If I make a query for a field in the 'businessUsers' it's working OK:
return FirebaseFirestore.instance.collection("businessUsers").where('xxx',
isEqualTo:filterBusinessResult ).snapshots().map(_businessListFromSnapshot);
but how can I make a query to 'campaigns' collection field?
I tried
return FirebaseFirestore.instance.collection("businessUsers").doc().collection("campaigns").where('campaignCategory', isEqualTo:filterBusinessResult ).snapshots()
.map(_businessListFromSnapshot);
but it wont work.
Its important to note, that I need all the data with 'campaignCategory' == filterBusinessResult
any idea?
It depends on whether you want to query a specific user's campaigns, or the campaigns of all users together.
If you want to query the campaigns of a specific user, you need to query under their document:
FirebaseFirestore.instance
.collection("businessUsers").doc("your user ID").
.collection("campaigns")
.where('campaignCategory', isEqualTo:filterBusinessResult)
So you have to know the ID of the businessUsers document here.
If you want to query across all campaigns subcollections are once, that is known as a collection group query and would look like this:
FirebaseFirestore.instance
.collectionGroup("campaigns")
.where('campaignCategory', isEqualTo:filterBusinessResult)
The results are going to documents from the campaigns collection only, but you can look up the parent document reference for each DocumentSnapshot with docSnapshot.reference.parent.parent.
When querying something, .doc() requires the id of the document you're trying to get. So it's failing because it doesn't know which document in the businessUsers collection you're trying to fetch a subcollection on. You probably want to use a .collectionGroup() query here. They let you query all subcollections at once (see documentation here). With FlutterFire specifically, it's going to be something like:
var snapshots = FirebaseFirestore.instance.collectionGroup("campaigns")
.where("campaignCategory", isEqualTo: filterBusinessResult)
.snapshots();
I am building a private chat feature for my app. I have chosen Firestore as my back end and below is how chat threads and messages are structured.
privateChats - chatId1 - chatId1 - messageId1, messageId2,...
collection - document - collection - documents
here is the screenshot
What I am trying to achieve is to get snapshots of every chat threads(chatId1, chatId2,...) with their corresponding message(last document/message was sent) and display like below - refer Chat screen
I have tried something like that
databaseRef.collection('privateChats').where('chatId', whereIn: chatList).snapshots();
However streams which are returned from above snapshots only listen for changes on fields where createdAt field exists.
Which gives me an only option to get individual snapshot for each chat threads like that
databaseRef.collection('privateChats').doc('chatId1).collection('chatId1).snapshots();
databaseRef.collection('privateChats').doc('chatId2).collection('chatId2).snapshots(); and somehow combine these snapshots into single stream (I don't know how)
So my question is - is there a way to get snapshots of each chat threads with just a single query when given list of chat ids? If not, what could be the solution? Should I come up with different cloud firestore structure?
Thanks
what i think you can do is create a doc for each chatRoom ..like say
databaseRef.collection('privateChats').doc('chatId1+chatId2')
then both users id1 and id2 can only access the document
I solved my problem using rxdart MergeStream function as emir adejuwon suggested
I am implementing a one-to-one chat app using firestore in which there is a collection named chat such that each document of a collection is a different thread.
When the user opens the app, the screen should display all threads/conversations of that user including those which have new messages (just like in whatsapp). Obviously one method is to fetch all documents from the chat collection which are associated with this user.
However it seems a very costly operation, as the user might have only few updated threads (threads with new messages), but I have to fetch all the threads.
Is there an optimized and less costly method of doing the same where only those threads are fetched which have new messages or more precisely threads which are not present in the user's device cache (either newly created or modified threads).
Each document in the chat collection have these fields:
senderID: (id of the user who have initiated the thread/conversation)
receiverID: (id of the other user in the conversation)
messages: [],
lastMsgTime: (timestamp of last message in this thread)
Currently to load all threads of a certain user, I am applying the following query:
const userID = firebase.auth().currentUser.uid
firebase.firestore().collection('chat').where('senderId', '==', userID)
firebase.firestore().collection('chat').where('receiverId', '==', userID)
and finally I am merging the docs returned by these two queries in an array to render in a flatlist.
In order to know whether a specific thread/document has been updated, the server will have to read that document, which is the charged operation that you're trying to avoid.
The only common way around this is to have the client track when it was last online, and then do a query for documents that were modified since that time. But if you want to show both existing and new documents, this would have to be a separate query, which means that it'd end up in a separate area of the cache. So in that case you'll have to set up your own offline storage on top of Firestore's, which is more work than I'm typically willing to do.
I'm using Firebase Cloud Firestore and can't figure out how to access documents without knowing the specific path. The database structure is users/{user id}/favourites/{favourite id}. There are no fields in users/{user id} only subcollections. Knowing the user id, i can get the favourites for the user, but I can't get a list of users to get everyone's favourites. Here is the code I am trying (Java admin SDK):
db.collection("users").get().get()
which results in an empty Iterable with no DocumentSnapshots.
How can I get a list of the most popular favourites?
EDIT: I've discovered I can get a list of users with no fields if I add a field. Even if I delete it later, it still appears as a document in the collection.
EDIT2: I've discovered that I can create an empty document, so I'm just doing that for now. As a one-off, I can get a list of all users from firebase auth and look up which ones have a favourites collection and just set those to empty documents.
Regarding the actual limitations in querying data based on subcollections values, what is the suggested way to manage multitenancy in Firestore?
I would like to be able to retrieve and limit access to data related to entities/companies the user is part of.
Example data structure :
/companies/{companyId}/users/
/companies/{companyId}/users/{user}/roles
/companies/{companyId}/docs/
Can /companies/{companyId}/users/ be a collection?
How can I only retrieve companies where user own a role in /companies/{companyId}/users ?
Firestore paths alternate from collection to document and back again:
/collection/document/subcollection/subdocument
So yes, in this case, you would have collections of companies, users, and docs. Collections are also implicit in that they are created automatically when documents exist in them, and removed when no documents exist in them.
At present, subcollection queries (e.g. "all users in a given company") aren't supported, so you'll have to structure your query the other way around: having a users collection with company as a property, when performing a query to find all users in that company.
ref.collection('users').where('company', '==', 'ACME').get().then((document) => {/* Do stuff here */});