Trying to do a select where query in Firebase and add the data to a recyclerview

Question

Here is my Firebase structure

I'm trying to select all the IDs with the same date and populate a recycler view with it, here is my code snippet:

 private void updateValues()
    {
        if(rAuth !=null && rUser!=null)
        {
            final String date="15/03/2018";
            final DatabaseReference rRef =
                    FirebaseDatabase.getInstance().getReference()
                    .child("Users")
                    .child("Transactions");

            rRef.child("Expense").addValueEventListener(new ValueEventListener()
            {
                @Override
                public void onDataChange(DataSnapshot rSnap)
                {
                    for(DataSnapshot d: rSnap.getChildren())
                    {
                        rRef.child(d.getKey())
                                .child("Date")
                                .addListenerForSingleValueEvent(new ValueEventListener()
                                {
                                    @Override
                                    public void onDataChange(DataSnapshot dataSnapshot)
                                    {
                                        if(date.equals(dataSnapshot.getValue().toString()))
                                        {
                                            recordItems.add(new recordItems(iconGetter(d.child("Type").getValue().toString()),
                                                    d.child("Description").getValue().toString(),
                                                    d.child("Type").getValue().toString(),
                                                    d.child("Value").getValue().toString(),
                                                    d.child("Date").getValue().toString()));
                                        }
                                    }

                                    @Override
                                    public void onCancelled(DatabaseError databaseError)
                                    {

                                    }
                                });
                    }
                    initRecycler();
                }

                @Override
                public void onCancelled(DatabaseError databaseError)
                {

                }
            });

now since i'm trying to access DataSnapshot d from an inner class I need to make it final, but if I do that, I can't iterate it anymore. I am a bit stuck here since it's my first time using Firebase. I have only used SQL in the past.

recordItems is my model(is that what it's called?) class for storing and providing values to the recycler adapter

Is there a better way to do this? I need to sort these by date, I thought about restructuring the database but I would prefer if there was another way.

Forgive my messy code, I intend to fix it once I get it working. Thanks for any help in advance.

You wanna retrieve all the expenses based on the given date ? — Niamatullah Bakhshi, Mar 14 '18 at 22:20
For restructuring the data like in ASC or DESC Firebase doesn't provide such methods. Have a look at [this](https://stackoverflow.com/questions/34156996/firebase-data-desc-sorting-in-android) answer. — Niamatullah Bakhshi, Mar 14 '18 at 22:40

yotam ravits · Accepted Answer · 2018-03-15T11:37:30.093

First of all you should fix those code line and add the User-id:

 final DatabaseReference rRef =
                FirebaseDatabase.getInstance().getReference()
                .child("Users")
                .child("Transactions");

Should look like that:

 final DatabaseReference rRef =
                FirebaseDatabase.getInstance().getReference()
                .child("Users")
                .child(userId)
                .child("Transactions");

Now, if you want to make your code more efficient you can get only the desired dates with the next query:

 final Query refQuery =
                FirebaseDatabase.getInstance().getReference()
                .child("Users")
                .child(userId)
                .child("Transactions")
                .child("Expense")
                .orderByChild("Date").equalTo(date);

Then, you don't even need to call the addListenerForSingleValueEvent method, because Firebase Realtime-Database always retrieve all the children of the specified Reference.

So all you need is to add your Code line inside the foreach loop:

for (DataSnapshot d : dataSnapshot.getChildren()){ 
     recordItems.add(new recordItems(iconGetter(d.child("Type").getValue().toString()),
           d.child("Description").getValue().toString(),
           d.child("Type").getValue().toString(),
           d.child("Value").getValue().toString(),
           d.child("Date").getValue().toString()));
}

And don't forget to notify yout adapter after adding all the new items to the list with adapter.notifyDataSetChanged() and of course after you called initRecycler(); in the beginning of this whole code.

Hope I helped! You are welcome to check my solution and tell if there are any problems

Thanks a LOT!!! That worked, missing the UID was so stupid too, I probably shouldn't stay up coding so late making such stupid mistakes. — Manan Adhvaryu, Mar 14 '18 at 23:06

score 1 · Answer 2 · answered Mar 14 '18 at 22:34

If you wanna retrieve all those Expense childs based on the given date

You need to declare your given date value as Global .

I would recommend you to use addChildEventListener and override all the methods.

Then, You have to create a pojo class for getting all those values in the form of an object.

Give this a try :

First create a class with the name :

ExpenseModel.java

paste this on it .

public class ExpenseModel {

    String Date,Description,Type,Value;

    public  ExpenseModel(){

    }


    public ExpenseModel(String date, String description, String type, String value) {


        Date = date;
        Description = description;
        Type = type;
        Value = value;
    }




    public String getDate() {


        return Date;
    }

    public void setDate(String date) {


        Date = date;
    }

    public String getDescription() {


        return Description;
    }

    public void setDescription(String description) {


        Description = description;
    }

    public String getType() {


        return Type;
    }

    public void setType(String type) {


        Type = type;
    }

    public String getValue() {


        return Value;
    }

    public void setValue(String value) {


        Value = value;
    }
}

And The method should be something like this

final String date="15/03/2018";

private void updateValues()
{
    if(rAuth !=null && rUser!=null)
    {
        final DatabaseReference rRef =
                FirebaseDatabase.getInstance().getReference()
                        .child("Users")
                        .child("Transactions");

        rRef.child("Expense").addChildEventListener(new ChildEventListener() {









            @Override
            public void onChildAdded(DataSnapshot dataSnapshot, String s) {


                ExpenseModel expenseModel =  dataSnapshot.getValue(ExpenseModel.class);



                assert expenseModel != null;
                if(expenseModel.getDate().equals(date)){


                    // Add it to the recyclerView
                    // And call notifyDataSetChanged()

                    yourAdapter.add(expenseModel);
                    yourAdapter.notifyDataSetChanged();


                }
            }

            @Override
            public void onChildChanged(DataSnapshot dataSnapshot, String s) {


            }

            @Override
            public void onChildRemoved(DataSnapshot dataSnapshot) {


            }

            @Override
            public void onChildMoved(DataSnapshot dataSnapshot, String s) {


            }

            @Override
            public void onCancelled(DatabaseError databaseError) {


            }
        });

Hope this at least helps till some extent, let me know if you still faced any problem.

Cheers

Hey, thanks for the answer, even though the above solution worked this one also seems interesting. I didn't understand this though yourAdapter.add(expenseModel); yourAdapter.notifyDataSetChanged(); am I supposed to replace the recordItems with expenseModel? and is yourAdapter the recyclerviewadapter or something else. sorry if these are all really silly questions. I'm still learning. — Manan Adhvaryu, Mar 14 '18 at 23:08
happy to hear that buddy, The data comes in the form of `ExpenseModel` from firebase. replace yourAdapter with your own Adapter Class which you have created in order to populate your RecyclerView . and yes the recyclerviewadapter as you said. — Niamatullah Bakhshi, Mar 14 '18 at 23:14

Trying to do a select where query in Firebase and add the data to a recyclerview

2 Answers2