从Firebase实时数据库中获取并比较键和值

Question

I'm trying to make an app in which user store his Data. I've used user shared preferences to save user login details but still for security purpose, i made an activity(Verify Passcode Activity) that ask user Passcode to allow access on the data. Now i'm able to save, fetch and delete data. But in my Verify Passcode Activity, i just want to fetch that particular key and value where passcode is stored. I don't want to fetch complete data in Verify Passcode Activity.

Below is the code which i used to save passcode to database:-

databaseReference.child(uniqueID).setValue(passcode);

Below is the code i'm tried to fetch only passcode:-

dbreference.child(uniqueID).orderByChild("passcode").equalTo(pass).addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
        if (dataSnapshot.exists()){
            Toast.makeText(getApplicationContext(), "Data exist", Toast.LENGTH_LONG).show();
        }else{
            Toast.makeText(getApplicationContext(), "Data doesn't exist", Toast.LENGTH_LONG).show();
        }
    }

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

    }
});

Here uniqueID is "abhishek88666kumar" and pass is a variable used for getText() .

Here is the screenshot of my Firebase Database :-

Database Screenshot

Here is Verify Passcode Activity Screenshot:-

Please have a look at Database Screenshot and Verify Passcode Activity Screenshot.

Agenda:

1. getText() from textView inside activity.

2. getValue from firebase realtime database (only for current user. 'abhishek88666kumar' in our case).

3. compare if 1 and 2 are same or not. (If same then redirect to MainActivity else show error.)

Please tell me what i'm doing wrong.

Answer 1

Assuming pass is a value like 1234 , this line:

dbreference.child(uniqueID).orderByChild("passcode").equalTo(pass).addListenerForSingleValueEvent(...

Should be:

FirebaseDatabase.getInstance().getReference("passcodes").orderByValue().equalTo(pass).addListenerForSingleValueEvent(...

This way the DataSnapshot will contain all child nodes of passcodes that have the value 1234 , ie "abhishek88666kumar" in your JSON sample.

Also be sure to study the documentation on sorting and filtering data .

Answer 2

This is the first way to compare firebase data.

btnSave.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                passcode = editText.getText().toString();

                Toast.makeText(getApplicationContext(), "Data :"+passcode, Toast.LENGTH_LONG).show();

                DatabaseReference ref = FirebaseDatabase.getInstance().getReference("passcode");
               Query applesQuery = ref.orderByValue().equalTo(passcode);

                applesQuery.addListenerForSingleValueEvent(new ValueEventListener() {
                    @Override
                    public void onDataChange(DataSnapshot dataSnapshot) {


                        if (dataSnapshot.exists()){

                            Toast.makeText(getApplicationContext(), "Data exist", Toast.LENGTH_LONG).show();
                        }else{
                            Toast.makeText(getApplicationContext(), "Data doesn't exist"+passcode, Toast.LENGTH_LONG).show();
                        }
                    }

                    @Override
                    public void onCancelled(DatabaseError databaseError) {
                        // Log.e(TAG, "onCancelled", databaseError.toException());
                    }
                });

            }
        });

This is the second way to compare firebase data.

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

            check = editText.getText().toString();

            Toast.makeText(getApplicationContext(), "Data :"+check, Toast.LENGTH_LONG).show();

            DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("passcode");
           // Query applesQuery = ref.child("Customers").orderByChild("abhishek88666kumar").equalTo(passcode);

            ref.addListenerForSingleValueEvent(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {

                    Map<String, Object> map = (Map<String, Object>) dataSnapshot.getValue();
                    if(map.get("abhishek88666kumar")!=null){
                        passcode = map.get("abhishek88666kumar").toString();

                        if (passcode.equals(check))
                        {
                            Toast.makeText(getApplicationContext(), "Data exist", Toast.LENGTH_LONG).show();
                        }
                        else{


                            Toast.makeText(getApplicationContext(), "Data doesn't exist"+check, Toast.LENGTH_LONG).show();
                        }

                    }

                }

                @Override
                public void onCancelled(DatabaseError databaseError) {
                    // Log.e(TAG, "onCancelled", databaseError.toException());
                }
            });

        }
    });

Both are working. Hope it's help full for you. thank you.

Answer 3

Thanks to all for your help :) Your answer didn't worked for me but with the help of your answers and my few knowledge, I made a solution for my problem myself. Here is the code that matches my requirement. This code is working exactly how I wanted.

dbreference = FirebaseDatabase.getInstance().getReference("passcodes");
                    Query query = dbreference.orderByKey().equalTo(currentUser); //current user is "abhishek88666kumar" in this case.
                    query.addListenerForSingleValueEvent(new ValueEventListener() {
                        @Override
                        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                            if (dataSnapshot.exists()){
                                String passcode = txtPasscode.getText().toString;//Passcode is 1234 in this case.
                                String fetchedValue = "";
                                for (DataSnapshot snap : dataSnapshot.getChildren()){
                                    fetchedValue = (String) snap.getValue();
                                }
                                if (!passcode.equals(fetchedValue)){
                                    Toast.makeText(getApplicationContext(), "Passcode doesn't match.", Toast.LENGTH_LONG).show();
                                }else{
                                    Toast.makeText(getApplicationContext(), "Passcode matched.", Toast.LENGTH_LONG).show();
                                }
                            }else{
                                Toast.makeText(getApplicationContext(), "No passcode found for this user", Toast.LENGTH_LONG).show();
                            }
                        }

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

                        }
                    });