I want to make a collection of users, users will have multiple stores as documents, each document have fields like storeName, storeAddress and availableProducts. My question is that how to manage availableProducts array? I know Firestore can't handle arrays, I should use HashMap. My available products may have field like product name, product price etc. I am new in Firebase, how can I manage availableProduct array using java in Android Studio?
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Are you asking how do you gather that data and put it into an Array or should you use a Map instead? Or how do you use a Map for that snapshot?Torewin– Torewin2018-07-06 03:43:54 +00:00Commented Jul 6, 2018 at 3:43
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should i use map or subcollection?sum20156– sum201562018-07-06 03:57:19 +00:00Commented Jul 6, 2018 at 3:57
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Personally, I would use a Map as it makes more sense and easier. Which way is better, is up for interpretation. You might want to create a class of availableProduct, but the Map works just as well.Torewin– Torewin2018-07-06 04:01:49 +00:00Commented Jul 6, 2018 at 4:01
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3 Answers
Good news guys, with the latest improvement to arrays you can add, update and remove an array element.
Check out this blog post: Better Arrays in Cloud Firestore!
You can do it like this
//Map to add user to array
final Map<String, Object> addUserToArrayMap = new HashMap<>();
addUserToArrayMap.put("arrayOfUsers", FieldValue.arrayUnion(mAuth.getCurrentUser().getUid()));
//Map to remove user from array
final Map<String, Object> removeUserFromArrayMap = new HashMap<>();
removeUserFromArrayMap.put("arrayOfUsers", FieldValue.arrayRemove(mAuth.getCurrentUser().getUid()));
//use either maps to add or remove user
db.collection("REFERENCE").document("mDocumentId")
.update(addUserToArrayMap);
2 Comments
speedox
really appreciate it man. This is perfect for a post voting system where there are two options up or down. But how would you do the query to get the final number of voters for each state (up or down)? I'm currently adding one whenever the users presses a vote but that isn't perfect obviously
Anga
@speedox It seems what you want is data at real time. This is a link to firebase documentation to achieve that firebase.google.com/docs/firestore/query-data/…
Edit: September 12, 2018
Starting with August 28, 2018, now it's possible to update array members. More informations here.
How to Add/Update/Remove array elements in firebase firestore?
The short answer is that you cannot! As in the official documentation regarding arrays:
Although Cloud Firestore can store arrays,
it does not supportquerying array members or updating single array elements.
So there is currently no way to add, update or remove a single array element in a Cloud Firestore database.
Seeing your database schema I can say that you don't have any arrays. The availableProducts is an object, beneath it there is a map named 0 which holds two String properties, spName and spPrice. If you want to update, let's say the price, please use the following code:
FirebaseFirestore rootRef = FirebaseFirestore.getInstance();
DocumentReference ref = rootRef.collection("gdgsghs.cok").document("Shsheg");
Map<String, Object> availableProducts = new HashMap<>();
Map<String, Object> zeroMap = new HashMap<>();
Map<String, Object> product = new HashMap<>();
product.put("spPrice", 63.121);
zeroMap.put("0", product);
availableProducts.put("availableProducts", zeroMap);
ref.set(availableProducts, SetOptions.merge());
Your price will be updated from 67.368 to 63.121.
This is how you can add a new item to an existing collection inside a document :
FirebaseFirestore.getInstance().collection("COLLECTION_NAME").document("DOCUMENT_ID").update("NAME_OF_COLLECTION_NODE",FieldValue.arrayUnion(NEW_VALUE_OF_ANY_TYPE))
check this link for more info: https://firebase.googleblog.com/2018/08/better-arrays-in-cloud-firestore.html
