Delete child from firebase

Question

I use following code to add a child and set a value to it in FireBase.

 String ref = Constants.Client+"/"+Constants.firebaseProjects+"/"+Constants.ProjectName+"/xyz";
 final DatabaseReference ref = FirebaseDatabase.getInstance().getReference(FirebaseRefer);
 ref.child("mockChild").push().setValue("")

What can I do to delete the "mockChild" ?

Martin Lund · Answer 1 · 2018-11-17T11:09:51.933

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ref.child("mockChild").removeValue();

Code to add child - ref.child("mockChild").push().setValue("Hello");

Code to remove child - ref.child("mockChild").removeValue();

Lets take an example in a user db:

ref.child("Users").child("User1").setvalue("User 1");
ref.child("Users").child("User2").setvalue("User 2");
ref.child("Users").child("User3").setvalue("User 3");

Now if you want to remove a specific user from the database you have to use this code:

ref.child("Users").child("User2").removeValue();

Since firebase is a key value database, it will remove the value from User2 and also the key since the key can't be on it's own. This will remove the entire reference to User2 from your database.

edited Nov 17 '18 at 11:09

answered Sep 27 '17 at 12:41

Martin Lund

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Will it not just remove the value in this case the "" , I want to delete the entire child. – Sreekanth Karumanaghat Sep 27 '17 at 12:42
It should remove the value, and when the value is removed, the key will be removed with it :) – Martin Lund Sep 27 '17 at 12:43
Are you sure that when value is removed the key will be removed? Because internally what the method does is that it will set a null object to the value. – Sreekanth Karumanaghat Sep 27 '17 at 12:45
Edited my answer, so you can see what happens, it removes the key if value has been removed – Martin Lund Sep 27 '17 at 12:54
where does -Kv2Nv.. come from? – Sreekanth Karumanaghat Sep 27 '17 at 12:55
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Random value, since nothing is specified, if you want to specify something you need to add another child. ref.child("mockChild").child("Key name here").setValue("The value"); – Martin Lund Sep 27 '17 at 12:57
Then you can remove that value by doing ref.child("mockChild").child("The key you want to remove").removeValue(); – Martin Lund Sep 27 '17 at 12:58
Ok, got it... But why is it not coming like this:- mockChild : "Hello" Why is it creating another child? – Sreekanth Karumanaghat Sep 27 '17 at 13:00
Thats just the way firebase handles it :) Firebase can't have empty keys, so the first child you make is kind of your main table. Then you can add more keys + values under here :) – Martin Lund Sep 27 '17 at 13:01
This is not my first child. – Sreekanth Karumanaghat Sep 27 '17 at 13:10

Alex Mamo · Answer 2 · 2017-09-27T12:45:27.023

4

To solve this, please use the following code:

String key = ref.child("mockChild").push().getKey();
ref.child("mockChild").child(key).setValue("yourValue");
ref.child("mockChild").child(key).removeValue(); // This is how you remove it

or you can use:

ref.child("mockChild").child(key).setValue(null);

It's also accepted and means that when you give Firebase a null value for a property/path, you indicate that you want to property or path to be deleted.

If you want to remove the entire child, then just use:

ref.child("mockChild").removeValue();

Note, it will remove everything that mockChild contains.

edited Sep 27 '17 at 12:45

answered Sep 27 '17 at 12:43

Alex Mamo

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I dont want to change the value in the child, I want to remove the child it self. – Sreekanth Karumanaghat Sep 27 '17 at 12:45
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I don't change the value. I just showed you how to set a value using `setValue()` method and then how to remove the same value using `removeValue()` method. Does it work? You only need to use `removeValue()` directly o the reference. – Alex Mamo Sep 27 '17 at 12:47
Please see also my updated answer. – Alex Mamo Sep 27 '17 at 12:48

Delete child from firebase

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