In my application I am storing the leaders where basically they are having some amount of points for completing the tasks. I am able to display them in recycle view based on their score. But Ideally I would need to show for the user in which position he sits ( 1st 2nd 3rd etc.) What would be a most efficient way to do so. Thank you in advance.
The best way to archive this it to order by the Score property:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
Query query = rootRef.child("Leaders").orderByKey("Score");
Please also take a look on official Firebase official documentation.
Related
I am trying to display images from Firebase's storage in my Android app inside a GridView.
I have done that, however, the images are displaying in an unknown order, and I have noticed that there is a 'Last modified' column inside Firebase's storage when I upload the images to it.
My question is: is there a way that I could sort the images inside the GridView in order to display them according to that date? (for example, the last one added, would have the latest 'Last modified' date and would be viewed first and such...)
This is my code:
val listRef : StorageReference = FirebaseStorage.getInstance().reference.child("images/posts/$userName")
val fileNameList: ArrayList<String> = ArrayList<String>()
listRef.listAll()
.addOnSuccessListener { it ->
it.items.forEach{
fileNameList.add(it.name)
}
gridView?.adapter = ImageRecyclerAdapter(activity, fileNameList,userName)
}
Note: the code is in Kotlin
I have looked everywhere and couldn't find anything that helps.
Any help is appreciated, thank you :)
According to the official documentation regarding StorageReference's listAll() method:
List all items (files) and prefixes (folders) under this StorageReference.
You might not be interested in listing folders within the reference you are pointing to.
That been said, the best option that you have is to store the URLs in a database. Such a database can be either Cloud Firestore or Firebase Realtime Database. This means that each object should have at least two fields, one for the actual URL and one for a timestamp. Please see in my answer from the following post how you can add a timestamp to Firestore:
ServerTimestamp is always null on Firebase Firestore
Is in Java, but you can simply convert it to Kotlin. Once you have all URLs in place, you can create a query and order the URLs according to the date. In Firebase Realtime Database the default order is ASCENDING, but below is how you can reverse the order:
How to arrange firebase database data in ascending or descending order?
While in Firestore, you can simply pass the desired direction to Query's orderBy(String field, Query.Direction direction) method.
I have a users collection with uId, name, photo
I have a visits collection with uId, userId, location
I have a recyclerview in which I want to show the location with the user name and photo
Can I use the reference field type? If so, how will Firestore know to link visits.userId == users.uId ?
Maybe I first need to query all the visits and then query the relevant user but 2 things:
It means querying a lot of times.
I didn't understand how to collect the joined collection into the adapter, which is based on one query?
Please advice
Thanks
current code
visitsList = db.collection("visitsList");
Query query = visitsList.whereEqualTo("userId",prefs.getString("id","")).orderBy("visitDate", Query.Direction.ASCENDING);
FirestoreRecyclerOptions<AVisit> options = new FirestoreRecyclerOptions.Builder<AVisit>().setQuery(query, AVisit.class).build();
adapter = new VisitsListAdapter(options, VisitsListActivity.this);
RecyclerView rv = findViewById(R.id.rvVisitsList);
rv.setHasFixedSize(true);
rv.setLayoutManager(new LinearLayoutManager(this));
rv.setAdapter(adapter);
The code is a simple query from the collection, not sure how to get the name and photo from the userId field in that collection.
Can I use the reference field type?
Yes, you can use a reference field.
If so, how will Firestore know to link visits.userId == users.uId ?
Firestore results always comes from a single collection (at the moment). It does not automatically join the document from the users collection when you're reading from the visits collection. You will have to do this yourself.
That indeed means you'll be executing multiple reads, but it's often not nearly as slow as you may think. See Google Firestore - how to get document by multiple ids in one round trip?
Update: To show data from the user profile in a list of visits, there are two main options:
load the additional user document in populateView or with a custom parseSnapshot implementation.
duplicate the relevant user data in the visits collection (which is quite normal in NoSQL databases). Also see Alex' answer here: indexed query with FirestoreRecyclerAdapter.
I am implementing Firebase Realtime Database for my app.
The database contains a lot of entries that will continue to grow in the future.
I want to retrieve only a specific child from the database, but i can't find any implementation for doing that.
In Firebase too the implementation retrieves all the entries from the database.
This will be cumbersome in the future.
Is there any way to retrieve only specific entries or just one entry(depending upon the customisation)?
Please help.
#ALex Mamo: This is the database image
Perhaps you are refering to shallow query, which only read the first child ? In this case you might want to look at the API implementation as mentioned here:
Firebase (2016) Shallow Query
There are two different ways of getting it. You'll have to change 'messages' to the name of your database. Replace PostTitle with the specific data you're trying to receive.
var rootRef = firebase.database().ref().child("messages");
rootRef.on("child_added", snap=> {
var postTitle = snap.child("PostTitle").val();
or
exports.sendPushNotification = functions.database.ref('/messages/{id}').onWrite((change, context) => {
const afterData = change.after.val();
const postTitle = afterData.PostTitle;
if you want retrieve few records this might help. as per image structure attached.
you can restructure the data, and use set method with keys as 0,1,2.... instead of "LK34h...."->0 .
use set method and store latest index value.
you retrive like this
firebase.database().ref().child('users_Post/0').on('value',sn=>{ console.log(sn.val())//use sn.val() })
I am making an Android app with Firebase and I want to add sections to each FirebaseUser (like wins and losses) but I don't think you can add to those objects. Should I just use the Realtime Database to do this or is there a better way?
Thanks in advance!
DatabaseReference ref1= FirebaseDatabase.getInstance().getReference();
DatabaseReference ref2,ref3;
ref2= ref1.child(user);//user is the name of user
ref2.child("Wins").setValue(""what he won);
ref2.child("Loose").setValue(""what he Lose);
Here I created a child to root node with user name, added sub children(Win & Lose) to user and then I set values to these children.
And you can retrieve that data too based on your query.
Refer following link once.
https://firebase.google.com/docs/database/android/start/
I have the following structure saved in my database:
What I want is I want the databaseReference to recognise the entire node using only the unique imageUIDh and display the content of all fields like postedAtTime, postedOnDate etc.
Is this possible in Firebase? Is there some alternative to achieve what I want?
Please let me know.
You can use Query
ref = FirebaseDatabase.getInstance().getReference();
ref.orderByChild("imageUIDh").equalTo(imageUIDh).addValueEventListener(valueEventListener);
Hope this helps :)