如何在不知道孩子的情况下根据里面的价值获得孩子。 在 android firebase 实时数据库中

Question

I have a node for the pharmacies accounts and the children are the id of the pharmacies each child contain the name and the id of the pharmacy and some more info. Now I have the pharmacy name and want to get the pharmacy ID is there any function that can do this?

Answer 1

What you're looking for is a database query, which allows you to filter the results under a node based on a property value.

In this case that'd be something like this:

DatabaseReference ref = FirebaseDatabase.getInstance().getReference("Pharmacies");
Query query = ref.orderByChild("PharmacyName").equalTo("El Ezaby");
query.get().addOnCompleteListener(new OnCompleteListener<DataSnapshot>() {
    @Override
    public void onComplete(@NonNull Task<DataSnapshot> task) {
        if (!task.isSuccessful()) {
            Log.e("firebase", "Error getting data", task.getException());
        }
        else {
            DataSnapshot result = task.getResult();
            for (DataSnapshot snapshot: result.getChildren()) {
                Log.i("firebase", snapshot.child("PharmacyID").getValue(String.class));
            }
        }
    }
});

The loop over result.getChildren() is needed since a query can have multiple results. Even though it may have only one result here, you'll still need the loop.

Answer 2

I have used the above code but there was an error at query.get

The code below worked with me

 DatabaseReference databaseReference1=FirebaseDatabase.getInstance().getReference("Pharmacies");
     databaseReference1.addValueEventListener(new ValueEventListener() {
         @Override
         public void onDataChange(@NonNull DataSnapshot snapshot) {
           for(DataSnapshot dataSnapshot:snapshot.getChildren()){
               Pharmacies pharmacies=dataSnapshot.getValue(Pharmacies.class);
               if(pharmacies!=null){
                   if(pharmacyName.contains(pharmacies.getPharmacyName())){
                        Log.e("firebase", dataSnapshot.child("PharmacyID").getValue(String.class));
                        pharmacyid=dataSnapshot.child("PharmacyID").getValue(String.class);

                   }
               }
           }
         }

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

         }
     });