CODEWITHSUNDEEP
androidfirebasefirebase-realtime-databasefirebaseui
Markus Biermeier
Markus Biermeier

Reputation: 103

Orderbychild reverse

I want to order my posts in the FirebaseRecyclerView by the String Votes. It contains a number as a String. If I write orderbychild("Votes") it shows up the smallest number first.

How can I turn that around? Cheers!

Upvotes: 3

Views: 4802

Answers (5)

Miftah Classifieds
Miftah Classifieds

Reputation: 291

I would like to add just one more thing to @Ari approch.

private Query getQuery() {
    Query query;
    if(last_value == -1) {
        query = getPostViewCountRef()
                .orderByChild("negativeViewsCount")
                .limitToFirst(ITEMS_PER_PAGE);
    }else {
        query = getPostViewCountRef()
                .orderByChild("negativeViewsCount")
                .startAfter(last_value)
                .limitToFirst(ITEMS_PER_PAGE);
    }
    return query;
}

as you can see we limitToFist instead of limitTolast

Upvotes: 0

Adam Rhoades
Adam Rhoades

Reputation: 37

the code below is how I fixed the issue. it uses an 3 integers - a max value the max value is equal to what ever you want with in the bounds of the datatype restrictions.

int round = 5;
int roundKills = 1000;
int points = 500;
round = round-99999;
roundKills = roundKills-999999;
points = points-99999999;
String oundkills = Integer.toString(roundKills);
String oints = Integer.toString(points);
String ound = Integer.toString(round);

LeaderBoardInput leaderBoardInput = new 
LeaderBoardInput(user,"SM",oundkills,oints,ound);

the LeaderboardInput class is just getters and setters for values that are being passed to the database

reference.child(user+System.currentTimeMillis()).setValue(leaderBoardInput);

when you pull the value, you would do something like the following:

round = round+99999;
roundKills = roundKills+999999;
points = points+99999999;

for your example if you have 5 votes and a max vote of 9,999,999 the code would look like this

int votes = 5;
long invertVotes = votes - 9999999;
String dbVotes = Integer.toString(invertVotes);
rootNode = FirebaseDatabase.getInstance();
reference = rootNode.getReference("scores");
reference.child("Votes"+System.currentTimeMillis()).setValue(dbVotes);
Query reference = FirebaseDatabase.getInstance()
                    .getReference().child("Votes").orderByChild("Votes");

                reference.addListenerForSingleValueEvent(new ValueEventListener() {
                    @Override
                    public void onDataChange(DataSnapshot dataSnapshot) {
                        //parse data to recycler view adapter and call //notifyDatasetChange()
                            Iterable<DataSnapshot> children = dataSnapshot.getChildren();
                            for (DataSnapshot child : children) {
                                Votes voteValues = child.getValue(voteinput.class);
int value = votevalues.getvotes()+9999999;
                                scores.add(new Votes( value));
                              
                            }
                            getdb = false;
                    }
                });

with Votes be a getter setter class and the scores variable being a list of the Votes class instances this will order votes 9999994 in db but print 5 to list out put of multiple values will 5 4 3 2 1 instead of 1 2 3 4 5

Upvotes: 0

Ari
Ari

Reputation: 7556

A quick and rather flexible way to do this on server side is to add an extra field and index your data both with Votes and negativeVotes, where negativeVotes=-Votes

Then for reverse order you do this:

orderbychild("negativeVotes")

And for regular order you do this:

orderbychild("Votes")

Upvotes: 3

Diego Ven&#226;ncio
Diego Ven&#226;ncio

Reputation: 6007

A way that I think better is ordering in client-side using reverse().

mLayoutManager = new LinearLayoutManager(getActivity());
mLayoutManager.setReverseLayout(true);
mLayoutManager.setStackFromEnd(true);

Upvotes: 1

Mathew Berg
Mathew Berg

Reputation: 28750

You don't necessarily turn it around.

Let's say your data looks like this:

{ 
    "polls":  {
        "id1": { "name": "lorem", "votes": 4 }
        "id2": { "name": "ipsum", "votes": 3 }
        "id3": { "name": "dolor", "votes": 5 }
        "id4": { "name": "sit", "votes": 2 }
        "id5": { "name": "amot", "votes": 6 }
    }
}

If for instance you need the top 4 you would do this:

.orderByChild("Votes").limitToFirst(4)

Would return: 

{
    "id4": { "name": "sit", "votes": 2 }            
    "id2": { "name": "ipsum", "votes": 3 }
    "id1": { "name": "lorem", "votes": 4 }          
    "id3": { "name": "dolor", "votes": 5 }
}

If you want the other end, you would do this instead:

.orderByChild("Votes").limitToLast(4)

And the return would be:

{
    "id2": { "name": "ipsum", "votes": 3 }
    "id1": { "name": "lorem", "votes": 4 }          
    "id3": { "name": "dolor", "votes": 5 }
    "id5": { "name": "amot", "votes": 6 }
}

If you need all of them, just order in the ui.

Upvotes: 2

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