I am using Vue.js and Firebase Firestore. Now I have two collectionsusers and orders. In the orders collection, I have already stored the id of each document of user collection. I now have to fetch the details of the corresponding users from this. How am I supposed to go about it?
This is what I've done so far
let orderRef = db.collection("orders")
orderRef.onSnapshot(snapshot => {
snapshot.docChanges().forEach(change => {
if (change.type == "added") {
let doc = change.doc;
this.orders.push({
id: doc.id,
orderData: doc.data().orderData,
user_id: doc.data().user_id,
userInfo: db.collection("users").doc(user_id),
});
}
});
});
I need to store user data in userInfo.Thanks in advance
Firestore doesn't support foreign key like SQL database, so you can't retrieve nested data like SQL.
In Firestore you need to fetch referenced data separately, either you can fetch all users data separately in parallel with orders data and store it in map, or if you don't need users data initially then fetch each users data when needed like when you check details of each order.
I think that you're structuring your data as if you were working in a relational database. Firestore is a no-SQL database that doesn't have any notion of reference, the only thing Firestore understands are key-values, documents and collections, everything else has to me modeled on top of that. See Firestore data model.
In Firestore relationships are usually modeled by storing the id of the document you'd like to "reference". In that sense you might not need to store the 'users' document inside the 'order' but the field 'user_id' would suffice. The caveat is that this data layout comes at the price of having to fetch the 'user_id' from orders before you can fetch the actual user data. You could read more about data denormalization and modeling relationships in articles link1, link2 and this other thread.
Also, it's worth noting that Firestore documents are limited in size to 1MB so with your actual configuration if the amount of info of 'user' documents increases it may get to a point where it would be necessary to reshape your documents structure.
All in all, if you don't want to change your data layout you would need to follow Ked suggestions and first retrieve the 'users' data to inline it into the 'userInfo' field.
Related
Is it possible to get data of sub-documents by reading only the main document in Firestore? Basically, the Firebase listCollections() method gives the id of subcollections, but how can we get their data?
I have tried for listCollections() to get the id of sub-collections, but have not found a way to get data sub-collections data.
Is it possible to get data of sub-documents by reading only the main document in Firebase?
In Firestore, the queries are shallow. This means that it can only return documents from the collection that the query is run against. So there is no way you can get documents along with the data that exists inside sub-collections in one go. A single query can only read fields of documents in a single collection.
If you need to get documents from sub-collection, you need to perform separate queries. If you have collections or sub-collections that have the exact same name then you can use a collection group query.
Firebase listCollectionIds(),Firebase listDocuments() are well documented by firebase but nobody use and write on it....
I think the best way is to list subcollection to your document throught the well-know get() and then process a foreach on result snapshot
snapshot.forEach(doc =>{
console.log(doc.id)
console.log(doc.data())
})
In the Security Rules! video #6 the suggestion is made to create a security rule using roles defined in a private_data sub collection with a single 'private' document:
allow update: if (get(/databases/$(database)/documents/restaurants/$(restaurantID)/private_data/private).data.roles[request.auth.uid] in ['editor', 'owner'];
Using the web API, how can I query the set of documents where a user has editor or owner permissions? I don't see that a where clause can reference sub-collection documents.
Something like
const q = query(
collection(db, 'restaurants'),
where(new FieldPath('private_data', 'private', 'roles', 'user_123'), 'in', ['editor', 'owner'])
);
Firestore queries can only filter documents based on the data in each document itself. There is no way to filter based on data in another document, either from the same collection or from another (sub)collection.
This means that while it is possible to restrict write and get (single-document read) operations based on the information in the roles subcollection, it is not possible to use those same documents in a query.
If you need this use-case, the common approach is to duplicate the necessary data from the subcollection(s) into the parent document, and the filter on it there. This complicating of data write to allow or simplify a certain read is a pattern you'll see quite regularly when dealing with NoSQL databases.
I have an Orders collection. It contains a field called venueId. And I'm querying against this field using isEqualTo. The venueId is the firebase user uid. I also have a venues collection. It contains this venueId and also has a list of VenueAdmins ids(These ids are also firebase user uids )The app is a point of sales app(pos). I need to query the orders collections so that valueAdmins and venueId see the correct stream. Is quite easy to query with venueId.. venueId,isEqualto, uid. I'm wondering what's the best approach to allow the venueAdmins see the stream as well.
|-Orders // collection
order. //doc
venueId:'2344567788999999'
|-Venues // collection
venue. //doc
venueAdmin: ['3333333333333','55555555555555555']
venueId:'2344567788999999'
My query builder so far: queryBuilder: (query) => query.where('venue.id', isEqualTo: uid)
Firestore does not have the capability to "join" documents from different collections in a single query. A single query can only consider documents in single collection at a time. The way you have your data structured now, it will require at least two queries. First, to find a venue, then second, to find the orders for an admin in a venue.
The only way to make this easier from the perspective of queries is to denormalize your data by duplicating venue data into the order documents. If each order also had a list of admins, then you could reduce this down to a single query.
I am trying to fetch all documents whose sub-collection contain a specific document ID. Is there any way to do this?
For example, if the boxed document under 'enquiries' sub-collection exists, then I need the boxed document ID from 'books' collection. I couldn't figure out how to go backwards to get the parent document ID.
I make the assumption that all the sub-collections have the same name, i.e. enquiries. Then, you could do as follows:
Add a field docId in your enquiries document that contains the document ID.
Execute a Collection Group query in order to get all the documents with the desired docId value (Firestore.instance.collectionGroup("enquiries").where("docId", isEqualTo: "ykXB...").getDocuments()).
Then, you loop over the results of the query and for each DocumentReference you call twice the parent() methods (first time you will get the CollectionReference and second time you will get the DocumentReference of the parent document).
You just have to use the id property and you are done.
Try the following:
Firestore.instance.collection("books").where("author", isEqualTo: "Arumugam").getDocuments().then((value) {
value.documents.forEach((result) {
var id = result.documentID;
Firestore.instance.collection("books").document(id).collection("enquiries").getDocuments().then((querySnapshot) {
querySnapshot.documents.forEach((result) {
print(result.data);
});
First you need to retrieve the id under the books collection, to be able to do that you have to do a query for example where("author", isEqualTo: "Arumugam"). After retrieving the id you can then do a query to retrieve the documents inside the collection enquiries
For example, if the boxed document under 'enquiries' sub-collection exists, then I need the boxed document ID from 'books' collection.
There is no way you can do that in a single go.
I couldn't figure out how to go backwards to get the parent document ID.
There is no going back in Firestore as you probably were thinking. In Firebase Realtime Database we have a method named getParent(), which does exactly what you want but in Firestore we don't.
Queries in Firestore are shallow, meaning that it only get items from the collection that the query is run against. Firestore doesn't support queries across different collections in one go. A single query may only use the properties of documents in a single collection. So the solution to solving your problem is to perform two get() calls. The first one would be to check that document for existence in the enquiries subcollection, and if it exists, simply create another get() call to get the document from the books collection.
Renaud Tarnec's answer is great for fetching the IDs of the relevant books.
If you need to fetch more than the ID, there is a trick you could use in some scenarios. I imagine your goal is to show some sort of an index of all books associated with a particular enquiry ID. If the data you'd like to show in that index is not too long (can be serialized in less than 1500 bytes) and if it is not changing frequently, you could try to use the document ID as the placeholder for that data.
For example, let's say you wanted to display a list of book titles and authors corresponding to some enquiryId. You could create the book ID in the collection with something like so:
// Assuming admin SDK
const bookId = nanoid();
const author = 'Brandon Sanderson';
const title = 'Mistborn: The Final Empire';
// If title + author are not unique, you could add the bookId to the array
const uniquePayloadKey = Buffer.from(JSON.stringify([author, title])).toString('base64url');
booksColRef.doc(uniquePayloadKey).set({ bookId })
booksColRef.doc(uniquePayloadKey).collection('enquiries').doc(enquiryId).set({ enquiryId })
Then, after running the collection group query per Renaud Tarnec's answer, you could extract that serialized information with a regexp on the path, and deserialize. E.g.:
// Assuming Web 9 SDK
const books = query(collectionGroup(db, 'enquiries'), where('enquiryId', '==', enquiryId));
return getDocs(books).then(snapshot => {
const data = []
snapshot.forEach(doc => {
const payload = doc.ref.path.match(/books\/(.*)\/enquiries/)[1];
const [author, title] = JSON.parse(atob(details));
data.push({ author, title })
});
return data;
});
The "store payload in ID" trick can be used only to present some basic information for your child-driven search results. If your book document has a lot of information you'd like to display once the user clicks on one of the books returned by the enquiry, you may want to store this in separate documents whose IDs are the real bookIds. The bookId field added under the unique payload key allows such lookups when necessary.
You can reuse the same data structure for returning book results from different starting points, not just enquiries, without duplicating this structure. If you stored many authors per book, for example, you could add an authors sub-collection to search by. As long as the information you want to display in the resulting index page is the same and can be serialized within the 1500-byte limit, you should be good.
The (quite substantial) downside of this approach is that it is not possible to rename document IDs in Firestore. If some of the details in the payload change (e.g. an admin fixes a book titles), you will need to create all the sub-collections under it and delete the old data. This can be quite costly - at least 1 read, 1 write, and 1 delete for every document in every sub-collection. So keep in mind it may not be pragmatic for fast changing data.
The 1500-byte limit for key names is documented in Usage and Limits.
If you are concerned about potential hotspots this can generate per Best Practices for Cloud Firestore, I imagine that adding the bookId as a prefix to the uniquePayloadKey (with a delimiter that allows you to throw it away) would do the trick - but I am not certain.
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 */});