In my firebase's database I have Users and every user has multiple stores that he ordered from and every store has multiple orders.
To fetch all the orders for specific store I write the following query and it works fine.
QuerySnapshot result = await Firestore.instance
.collection('users')
.document(userID)
.collection('Stores').
document(storeID).getDocuments();
However, I do not need that. I just need the stores that the user ordered from. In other words, I need list of storeIDs for specific user.
Here is my code but it doesn't work.
QuerySnapshot result = await Firestore.instance
.collection('users')
.document(userID)
.collection('Stores').getDocuments();
I just want the IDs
It's not possible with web and mobile clients to get only the IDs without the entire set of documents and their data. If you want a list of all IDs for all documents in a collection or subcolleciton, you're going to have to query that collection as you currently show in the second example. You can easily extract the IDs from the returned documents in the QuerySnapshot. But you are still paying the cost of a document read for each document in the collection, and waiting for all of their contents to transfer.
If you want, you can create your own backend endpoint API to use a server SDK to query for only the IDs, and return only the IDs, but you are still paying a document read for document.
Related
I'm trying to fetch a certain number of document for viewing it in a limit view table, for example 50 elements at the time, whenever the user clicks next it loads the next 50 element form the Firestore and shows it in the table, in order to reduce the data loaded from the firebase and not to slow down the application, since there may be millions of documents stored in the Firestore,
I've tried this solution but is it the best practice?
Thanks.
vehiclesCollection.snapshots().skip(10).take(10).map(
(event) {
print('some logic');
},
);
According to the Firebase docs and FlutterFire docs batching is possible!
It looks like this:
FirebaseFirestore.instance
.collection('users')
.limit(50)
.get()
.then(...);
In order to make it a working pagination you could add startAfterDocument to your query and give as parameter for each request the last element from the previously returned collection:
FirebaseFirestore.instance
.collection('users')
.limit(50)
.startAfterDocument(lastDocument)
.get()
.then(...);
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'm working on a Flutter app where each user can create projects, and share projects with other users. I've created a 'shares' collection, where each user's ID is a document, and within that document, all project IDs that have been shared with that user are collected like so, with a boolean that represents whether or not the share has been accepted yet:
Next, I created a collection of the projects themselves, like so:
Now, I'd like to query the 'projects' collection and return only the projects that are in a given user's 'shares' list. First off, how can I get each document in the share list's ID? And secondly, is it possible to compare that ID to the contents of a List using a .where() clause?
I've been trying something like this, but to no avail:
Stream<List<Map<String, dynamic>>> getListOfProjectsForUser({#required List<String> shares}) {
var ref = _firestore.collection('projects');
return ref
.where(shares, arrayContains: ref.id)
.snapshots()
.map((QuerySnapshot snapshot) => snapshot.docs.map((DocumentSnapshot doc) => doc.data()).toList());
}
I also tried this:
Stream<List<Map<String, dynamic>>> getListOfProjectsForUser({#required List<String> shares}) {
var ref = _firestore.collection('projects');
return ref
.where(shares, arrayContains: FieldPath.documentId)
.snapshots()
.map((QuerySnapshot snapshot) => snapshot.docs.map((DocumentSnapshot doc) => doc.data()).toList());
}
Is what I'm trying to do even possible? I've been messing with this for two days and my head's exploding. Any help would be greatly appreciated. Thanks in advance.
You'll need two operations.
Read the document for the user, to determine the list of project IDs.
Perform a in query for the project documents matching those IDs. The in operator accepts up to 10 IDs, so if you have more than 10 projects you'll need multiple queries and merge the results in your application code.
var citiesRef = db.collection("projects");
citiesRef.where(FieldPath.documentId, arrayContains: ['project1id', 'project2id']);
Also see:
The FlutterFire documentation for the where(field, whereIn:) operation
The FlutterFire documentation for the FieldPath.documentId field
First off, how can I get each document in the share list's ID?
For this, you're required to actually query the entire collection. You can iterate the results to collect the IDs of each document. There is no easy way to just get a list of IDs directly from web and mobile client code. See: How to get a list of document IDs in a collection Cloud Firestore?
And secondly, is it possible to compare that ID to the contents of a List using a .where() clause?
If you have a list of document ID strings in memory that could be any length, you will need to perform a query filtering projects for "projOwner" for each individual ID. There are no SQL-like joins in Firestore, so you can't simply join the two collections together with a single query.
Here's how you do a single one - you have to call out the name of the field to filter on:
firestore
.collection("projects")
.where("projOwner", isEqualTo: id)
If you have 10 or less share IDs in the list, you can use an "in" query to find matches from projects, and it will not work with any more.
firestore
.collection("projects")
.where("projOwner", whereIn: listOfIds)
So, if you think the list could ever be larger than 10, you should just start by performing individual queries for each share ID.
if 'arrayContains' is not working try 'whereIn'.
var citiesRef = db.collection("projects");
citiesRef.where(FieldPath.documentId, whereIn: ['project1id',
'project2id']);
when a new document is added, snapshot fetches all the documents including the new ones or only the newly added ones ? If it fetches all the documents every time then it will add to the billing cost. How to get around this problem ?
StreamBuilder(
stream:Firestore.instance
.collection('chat')
.orderBy('timeStamp', descending: true).snapshots(),
builder: (context, streamSnapshot) {}
);
While your snapshots() listener stays active, the server actively monitors for changes that are relevant to your listener. When there are such changes it only sends you new documents, or documents that were changed, to your client. The client then merges those updates with its local data, and presents you with a new complete QuerySnapshot.
According to the official doc : Here
There are two ways to retrieve data stored in Cloud Firestore. Either of these methods can be used with documents, collections of documents, or the results of queries:
Call a method to get the data.
Set a listener to receive data-change events.
When you set a listener, Cloud Firestore sends your listener an initial snapshot of the data, and then another snapshot each time the document changes.
You can get an array of the document snapshots by using the docs property of a QuerySnapshot. After that you'll have to loop through getting the data of the doc snapshots looking for your doc.
OR if you don't actually need the full QuerySnapshot, you can apply the filter using the where function before calling get on the query object
These are the most efficient way to get documents.
I am querying my Firestore database as follows:
final Query roasters = Firestore.instance
.collection('retailers')
.where('retail_category', isEqualTo: 'Coffee Roasters');
I am receiving the result back of all documents in the retailers collection which have 'retail_category' set as 'Coffee Roasters'.
The Problem
I instead want to turn retail_category into a separate collection and instead reference it in the retailer field (which would negate the following reference):
"retail_categories/hEN5fzNl2hEc2tEs05Wi"
I have tried the following:
final Query roasters = Firestore.instance
.collection('retailers')
.where('retail_categories', isEqualTo: ' qretail_categories/hEN5fzNl2hEc2tEs05Wi');
Here is my Firestore configuration:
Retailers
Retail Categories
It's not possible to reference data in documents outside of the collection being used for the query. For this reason, it's very common to duplicate data between documents that need to be used in queries for each collection. If you don't want to do that, you will have to make separate queries for each referenced document.