Get the pushed ID for specific value in firebase android

Question

I want to retrive the id that generated by firebase when I pushed value to it like next

I want to retrieve "-KGdKiPSODz7JXzlgl9J" this id for that email I tried by getKey() but it return "users" and when user get value it return the whole object from the id to profile picture and that won't make me get it as User object in my app

how solve this ?

    Firebase users = myFirebaseRef.child("users");
    users.orderByChild("email").equalTo("z@m.com").addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {

            dataSnapshot.getKey();
            Log.d("User",dataSnapshot.getRef().toString());
            Log.d("User",dataSnapshot.getValue().toString());
        }

        @Override
        public void onCancelled(FirebaseError firebaseError) {

            Log.d("User",firebaseError.getMessage() );
        }
    });

Would you consider iterating over the users dataSnapshot and using an identifier value (like the email for example) to see if you have a match and retrieve the values of that matching snapshot? — AL., May 07 '16 at 23:32
For next time: You've included a picture of the JSON tree in your question. Please replace that with the actual JSON as text, which you can easily get by clicking the Export button in your Firebase database. Having the JSON as text makes it searchable, allows us to easily use it to test with your actual data and use it in our answer and in general is just a Good Thing to do. — Frank van Puffelen, May 08 '16 at 04:23

Samuel Robert · Answer 1 · 2017-09-28T10:06:10.473

78

You can read the key from push() without pushing the values. Later you can create a child with that key and push the values for that key.

// read the index key
String mGroupId = mGroupRef.push().getKey();
....
....
// create a child with index value
mGroupRef.child(mGroupId).setValue(new ChatGroup());

mGroupId contains the key which is used to index the value you're about to save.

edited Sep 28 '17 at 10:06

answered Jan 23 '17 at 04:52

Samuel Robert

10,106
7
39
60

1

This helped, even though I am using JavaScript. – Eduard Aug 24 '18 at 18:40
But what if I have pushed the child already and later I want to get the key later? Is there any way to get that key? – Zeeshan Ahmad Khalil Apr 28 '20 at 08:14
@ZeeshanAhmadKhalil Depends, is the child you have created is in the same operation as you need to read the key? then you can use this method, if it is in the different part of the code or if you need in the future, you can check out Frank Van's answer below – Samuel Robert Apr 28 '20 at 11:03

Sattar · Accepted Answer · 2017-08-22T20:10:47.247

UPDATE 1: it can obtain also by one line

String key = mDatabase.child("posts").push().getKey();

//**************************************************************//

after searching and trying a lot of things i came to 2 ways to do that . 1. first one to get the key when i upload the post to the server via this function

 public void uploadPostToFirebase(Post post) {
      DatabaseReference mFirebase = mFirebaseObject
            .getReference(Constants.ACTIVE_POSTS_KEY)
            .child(post.type);
      mFirebase.push().setValue(post);
      Log.d("Post Key" , mFirebase.getKey());
 }

i used it in my code to get the key after i have already pushed it to node for it in my database

public void getUserKey(String email) {

    Query queryRef = databaseRef.child(Constants.USERS_KEY)
        .orderByChild(Constants.USERS_EMAIL)
        .equalTo(email);

    queryRef.addChildEventListener(new ChildEventListener() {
      @Override
      public void onChildAdded(DataSnapshot dataSnapshot, String s) {
        //TODO auto generated
      }

      @Override
      public void onChildChanged(DataSnapshot dataSnapshot, String s) {
        //TODO auto generated;
      }

      @Override
      public void onChildRemoved(DataSnapshot dataSnapshot) {
        //TODO auto generated;
      }

      @Override
      public void onChildMoved(DataSnapshot dataSnapshot, String s) {
        //TODO auto generated
      }

      @Override
      public void onCancelled(DatabaseError databaseError) {
        //TODO auto generated 
      }
  });
 }

score 17 · Answer 3 · edited Sep 16 '17 at 11:00

17

When you fire a Firebase query there can potentially be multiple results. So when you ask for the value of a query, Firebase returns a list of items. Even if there is only one matching item, it will be a list of one item.

So you will have to handle this list in your code:

users.orderByChild("email").equalTo("z@m.com").addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for (DataSnapshot child: dataSnapshot.getChildren()) {
            Log.d("User key", child.getKey());
            Log.d("User ref", child.getRef().toString());
            Log.d("User val", child.getValue().toString());
        }
    }

edited Sep 16 '17 at 11:00

Harsh Phoujdar

670
10
22

answered May 08 '16 at 04:23

Frank van Puffelen

565,676
79
828
807

Yes i know that but that doesn't answer my question for every child there exist a unique key for it i want to extract this Key if i use child.getKey() it return me "users" – Sattar May 09 '16 at 15:30
Can you set up a jsbin/jsfiddle that reproduces this behavior? – Frank van Puffelen May 09 '16 at 15:49
what do you mean by that ? – Sattar May 09 '16 at 20:45
1

@NandanKaushikDutta here is my answer to the question after i found how to solve it [link] (http://stackoverflow.com/a/39492322/3553843) – Sattar Sep 14 '16 at 13:58

WM1 · Answer 4 · 2016-12-07T18:12:45.960

In Java - Android Studio, you can get the unique pushed ID as the item is written to the db...

Per "Firebase's: Save Data on Android": You can use the reference to the new data returned by the push() method to get the value of the child's auto-generated key or set data for the child. Calling getKey() on a push() reference returns the value of the auto-generated key.

To get the reference at write time, instead of loading DATA with a single push()...

use push() to create a blank record in the database, return value is the record's reference.
use .getKey() to get the Key for that record.
use .setValue(DATA) to fill in the blank record

here's an example:

    FirebaseDatabase fb_db_instance = FirebaseDatabase.getInstance(); 
    DatabaseReference db_ref_Main = fb_db_instance.getReference("string_db_Branch_Name");

    hashMap_record = new HashMap<String, String>();           //some random data 
    hashMap_record.put("key_Item1", "string_Item1");
    hashMap_record.put("key_Item2", "string_Item2");

    DatabaseReference blankRecordReference = db_ref_Main ;   

    DatabaseReference db_ref = blankRecordReference.push();   //creates blank record in db
    String str_NEW_Records_Key = db_ref.getKey();             //the UniqueID/key you seek
    db_ref.setValue( hashMap_record);                         //sets the record

what happens if the object I want to save is not composed of string-only keys and/or values? — Chisko, Nov 27 '16 at 05:08
https://firebase.google.com/docs/database/android/read-and-write demonstrates what kind of data that firebase can handle... it's all JSON, and includes String, Long, Double, Boolean, Map, List — WM1, Dec 07 '16 at 18:21

score 7 · Answer 5 · edited Dec 02 '16 at 13:13

7

I solved it to get id you need to use firebase url

String uid = firebaseRef.child("users").push().getKey();
Log.i("uid", uid);

this will give you the key KG.....

edited Dec 02 '16 at 13:13

Dushyant Suthar

673
2
9
27

answered Sep 07 '16 at 06:30

Ekta Dushanj

119
2
5

score 3 · Answer 6 · answered Oct 29 '16 at 13:29

3

For those using TVAC Tutorials(https://www.youtube.com/watch?v=cSMMWOHkP68&list=PLGCjwl1RrtcTXrWuRTa59RyRmQ4OedWrt&index=16)

You can get Key using onClick method as follows:

   viewHolder.mView.setOnClickListener(new View.OnClickListener() {
       @Override
       public void onClick(View v) {

           String key = getRef(position).getKey();

          }
     });

answered Oct 29 '16 at 13:29

sley_paloh

31
1

Worked for me! But only if you use FirebaseUI library – Andrii Kovalchuk Oct 31 '16 at 21:24

score 2 · Answer 7 · answered Jul 09 '16 at 08:02

Just add new field to Users like userID, when you create new User add uid and than you can receive it by reading query

I'm doing it like this.

String userID;// in Users


Firebase users = myFirebaseRef.child("users");
    users.orderByChild("email").equalTo("z@m.com").addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            Users user= dataSnapshot.getChildren().iterator().next().getValue(Users.class);
            Log.d("User",user.getUserID());
        }

        @Override
        public void onCancelled(FirebaseError firebaseError) {
            Log.d("User",firebaseError.getMessage() );
        }
    });

score 2 · Answer 8 · answered Dec 19 '17 at 02:25

2

I had faced this problem and I found the solution, you can get it using this code:

dataSnapshot.getChildren().iterator().next().getKey()

answered Dec 19 '17 at 02:25

Abdalltif Basher

617
7
19

thanks, this is the correct answer. – Ruhith Udakara Oct 09 '21 at 16:44

mohamed orabi · Answer 9 · 2020-02-06T22:56:00.633

2

 // Unity, code in C#
{
 reference = FirebaseDatabase.DefaultInstance.RootReference;
 string s = reference.Push().Key;
 reference.Child(s).Child(Username).SetValueAsync(Username);
 Debug.Log(s);
}

edited Feb 06 '20 at 22:56

answered Feb 06 '20 at 21:47

mohamed orabi

21
2

1

Hi, you need to format the code using editing tools, and add explanation of how it works – Zain Feb 06 '20 at 21:51

score 1 · Answer 10 · answered Mar 19 '17 at 08:59

Another Option to get the unique Post-id from firebase is by getting key (dataSnapshot.getKey()) in @Override method public void onChildAdded and maintaining it locally for example

private void attachDatabaseReadListener() {
        if (mTaskEventListener == null) {
            mTaskEventListener = new ChildEventListener() {
                @Override
                public void onChildAdded(DataSnapshot dataSnapshot, String s) {

                Task friendlyMessage = dataSnapshot.getValue(Task.class);
                friendlyMessage.setId(dataSnapshot.getKey());

                System.out.println("friendlyMessage  = " + friendlyMessage);

                DummyContent.ITEMS.add(new DummyContent.DummyItem("" + DummyContent.ITEMS.size()+1,friendlyMessage.getStatus(),friendlyMessage.getSummary()));
            }

            public void onChildChanged(DataSnapshot dataSnapshot, String s) {}
            public void onChildRemoved(DataSnapshot dataSnapshot) {}
            public void onChildMoved(DataSnapshot dataSnapshot, String s) {}
            public void onCancelled(DatabaseError databaseError) {}
        };
                     mUserDatabaseReference.addChildEventListener(mTaskEventListener); // remove it
    }
}

dataSnapshot.getKey will set the unique post id in Task Instance and can be used later to perform any update operation.

score 1 · Answer 11 · answered Jun 18 '19 at 09:06

FirebaseDatabase firebaseDatabase = FirebaseDatabase.getInstance();
DatabaseReference databaseReference1 = firebaseDatabase.getReference("users");
databaseReference1.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {

                for(DataSnapshot dataSnapshot1 : dataSnapshot.getChildren()) {

                    String key = dataSnapshot1.getKey();
                    Log.d(TAG, "onCreate: key :" + key);

                    String email = dataSnapshot1.child("email").getValue(String.class);
                    String roomno =dataSnapshot1.child("address").getValue(String.class);
                    Log.d(TAG, "onDataChange: email: " + email);
                    Log.d(TAG, "onDataChange: address: " + address)
                }
            }
            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });

A little bit of explanatory text would improve this answer. – Laurenz Albe Jun 18 '19 at 09:29 — Laurenz Albe, Jun 18 '19 at 09:29

user12784852 · Answer 12 · 2020-01-27T11:31:48.143

Use this

 mFirebaseDatabase=mFirebaseDatabase.getInstance().getReference("tablename");
 Query query = mFirebaseDatabase.orderByChild("tablenme").getRef();


    query.orderByChild("Id").addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            for (DataSnapshot dataSnapshot1 : dataSnapshot.getChildren()) {
                String id =dataSnapshot1.child("Id").getKey();

                    String Name = dataSnapshot1.child("Name").getValue().toString();
                    String lastName= dataSnapshot1.child("lastname").getValue().toString();
                    flatDataGets.add(Name+"-"+lastname);



            }

            ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(RagisterActivity.this, R.layout.support_simple_spinner_dropdown_item, DataGets);
            arrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
            mRegisterSpinner.setAdapter(arrayAdapter);
            mRegisterSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
                @Override
                public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                  flatName =DataGets.get(position);


                }

                @Override
                public void onNothingSelected(AdapterView<?> parent) {

                }

            });

        }


            @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {

        }
    });

score 0 · Answer 13 · edited Oct 30 '20 at 11:44

0

Yes, you can retrieve the node or main child name by adding its name in that particular child as a key and value {main_child_name}.

edited Oct 30 '20 at 11:44

double-beep

5,031
17
33
41

answered Oct 30 '20 at 04:54

Vigneshwar A S

31
3

score -1 · Answer 14 · answered Mar 29 '19 at 10:48

Simply do similar:

 HashMap<String, Object> hashLcl = new HashMap<>();
    hashLcl.put("admin", firebaseUser.getUid());
    hashLcl.put("name", textPrm);
    DatabaseReference referenceLcl = FirebaseDatabase.getInstance().getReference();
    String keyLcl = referenceLcl.child("GroupChats").push().getKey();
    hashLcl.put("key", keyLcl);
    Task task = referenceLcl.child("GroupChats").child(keyLcl).setValue(hashLcl);
    task.addOnSuccessListener(aVoid -> {
        //the data is added and now we are sure to do something related
    });

This is the result:

Get the pushed ID for specific value in firebase android

14 Answers14

Linked