Suppose I have the following structure in Firestore:
Is there a way I can query (using the JS API) for a list of reviews from orders whose shopId is a specific value? Or am I required to add the shopId to the review document, too?
As far as I can see, you can get all orders of a specific shop, by querying like this:
var ordersRef = db.collection("orders");
var query = ordersRef.where("shopId", "==", "someId");
To get the corresponding reviews, you have to create a new reference that points to the review subcollection and read all reviews, a case in which there is no need to add the shopId as property within the review document.
If you wanted to use a collection group query, to get all reviews of a specific shop, then you would have needed that:
var reviews = db.collectionGroup("review").where("shopId", "==", "someId");
Related
After getting a snapshot for a particular document in a subcollection, I would like to get the associated data to the root document which it belongs to.
For example, there is a collection restaurants and each one has a products subcollection.
After searching for a particular product of a restaurant, how can I get the restaurant data which the product belongs to? Do I need to make another search or how can I get it from the product snapshot?
QuerySnapshot snapshot = await FirebaseFirestore.instance
.collectionGroup('products').get();
QueryDocumentSnapshot product = snapshot.docs.elementAt(0);
There's actually a very easy way to do this, and it takes advantage of the ref.path of the document. You can split the ref.path string into it's component sections - remember, it's the full "/" separated path to the document, so for example:
restaurants/{restaurantId}/products/{productId}
topCollection/{topdocumentId}/nextCollection/{nextDocumentId}/.../bottomCollection/{bottomDocumentId}
Clearly, the first two segments are the path to the "parent" document - regardless of the depth of the tree (I happen to have a very deep tree structure). You can then fetch the "top parent":
db.collection(topCollection).doc(topdocumentId).get()
To find the parent/restaurant document for product, you'll want to walk up the reference/parent chain:
var restaurantRef = product.reference.parent.parent;
You will still need to get that document with:
var restaurantDoc = await restaurantRef.get();
My db design is above picture. I wanna create a query which returns user where tags are matched. But i didnt any solution to query.
This is my flutter code:
But it doesnt work. How can i query array of map of document?
The courses is an array and not a map so you cannot use the dot notation to query. If the courses is made a collection (or a sub-collection) on it's own then you would be able to query users easily:
users -> {userId}
(col) (doc)
courses -> {courseId}
(col) (doc)
You would have to include a field userId in each course document which would be used to identify which user owns that course.
await firestore.collection("courses").where("tags", arrayContainsAny: tagKeys)
This will return all courses where the tags array contains at least 1 item in the tagKeys list. If you need exact match i.e. all the tags in tagKeys must be present in Firestore document then you would have to restructure the database as mentioned in this answer.
Fetching all matching documents might not be ideal since you just need user IDs that matches the tags. In that case you can store a field which contains tags from all the courses in a single array field in the user document.
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.
I am trying to structure my data such that when someone adds a new product to the database, all users receive the new product in their list and therefore the new product appears on their screen.
But if a user decides to delete that product, they can delete it but only for themselves. Is there a Cloud Firestore sorting/ordering/filtering that I should be using to accomplish this?
I thought I could use something like the following:
final theProduct = Provider.of<Products>(context);
products = await firestore.collection('products').getDocuments()
for (product in products.documents) {
await firestore.collection('products').add({
'nameOfProduct': theProduct.nameOfProduct
});
}
But I get a document property error.
Maybe I need to go in one more collection and then try something? But I also need to be able to retrieve the data back using the userID of the signed in user..
Any hints/helpful links would be greatly appreciated.
So I think what I want to do is iterate through all documents within a collection and then document().collection('').add() something to each of their collection. Hopefully that sheds some more light on my problem.
Thanks to those who commented. I found a way to implement this was to use the unique value that each product contains and add it to a list on a per user basis in Firestore. Then fetch that list from Firestore and filter out the corresponding products. No deleting necessary.
Question : a user decides to delete that product, they can delete it but only for themselves
Answer: U can create list in user profile section where u can have all the product document ids & u can use that document id to fetch particular product details & when user click on delete button u can remove that particular document id from there collection
Im not sure what r u doing with sample code over there.
If u want to add data to database then use :
await Firestore().collection('Products').add({
'nameOfProduct': theProduct.nameOfProduct,
});
this will generate document random id for your product.
To get data from particular id use :
DocumentSnapshot documentSnapshot = await Firestore().collection('Products').document('document').get();
then u can use that document snapshot to get data for particular key e.g.
documentSnapshot.data['Product Name']
I have a data schema where users can review products. user and product are vertices, and reviews is a MANY2MANY relation between users and products. reviews has edge properties such as title and body.
I want to write a query to get all reviews for a product, as well as the users that wrote the review. I can get the reviews using the following, but I don't know how to add all the user properties.
g.({product}).inE("reviews").values()
How can I get user information per review as well?
You could do something like this:
l = g.V(pvid). // start with a product vertex id
inE("reviews").as("r"). // label the review edges
outV().as("u"). // label the users
select("r", "u").by(valueMap()). // properties map
toList() // iterate traversal into a list
This will return a list of maps. Each map will have 2 keys, r and u, corresponding to the select("r", "u") step. Then the value of the r in the map are the properties for the review. Similarly the value of the u in the map are the properties for the user.
Related documentation
As step
ValueMap step