Getting child values in Firebase

Question

I have the following structure

root
  -class1
     -section1
        -student1
            -firstname
            -lastname
        -student2
            -firstname
            -lastname
     -section2
        -student1
            -firstname
            -lastname
        -student2
            -firstname
            -lastname

I need to get the section number (Section1, section2...) and for every section, the lastname for student2.
The problem that i facing is that it is all in a Fragment class in android that I need to display and nothing seems to be working. I have referred this for getting the children too, but the for loop somehow does not work and I get Null values on retrieval.

I need to get

section1, lastname (of student2 in section1)
section2, lastname (of student2 in section2)
...
and so on until all sections are exhausted

score 0 · Answer 1 · answered Aug 04 '17 at 20:33

0

U can make a model class like

class Class{
Arrylist<section> sections;
};

class section{
Arrylist<Student> students;
};

class Student{
String firstname, lastname;
};

then get the value of classes

have other way, without making many model classes, but that is more painful and time consuming . If u want that feel free to comment.

answered Aug 04 '17 at 20:33

Shahadat Hossain Shaki

796
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15

I would like to take a look at that as well. Thank you – evan Aug 04 '17 at 20:38
get the value in Object class. HashMap data= (HashMap) dataSnapshot.getValue(); then break the object into your desirable value. – Shahadat Hossain Shaki Aug 04 '17 at 20:41

score 0 · Answer 2 · answered Aug 07 '17 at 13:01

Please use the following code:

DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference classRef = rootRef.child("class1");
ValueEventListener eventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for(DataSnapshot ds : dataSnapshot.getChildren()) {
            String lastname = ds.child("student2").child("lastname").getValue(String.class);
            Log.d("TAG", lastname);
        }
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {}
};
classRef.addListenerForSingleValueEvent(eventListener);

Getting child values in Firebase

2 Answers2