如何在Android Studio中的Firebase中编辑特定孩子的值？

Question

Can you help me identify why my code is not working? I want to retrieve the value of the child rate in Firebase and display it on my EditText in Android Studio. Then when another value is entered in the EditText via button , the value of the child rate will be updated. Thanks.

package com.example.jordan.grat;

import ...

public class AdminActivity extends AppCompatActivity {

private Button mLogout, mAddDriver, mEditDriver, mUpdateRate;

private DatabaseReference mAdminDatabase;

private EditText mRateField;

private String mRate, mPassword;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_admin);

    mLogout = (Button) findViewById(R.id.logout);
    mAddDriver = (Button) findViewById(R.id.addDriver);
    mEditDriver = (Button) findViewById(R.id.editDriver);
    mUpdateRate = (Button) findViewById(R.id.updateRate);

    mRateField = (EditText) findViewById(R.id.rateField);

    mAdminDatabase = FirebaseDatabase.getInstance().getReference().child("Users").child("Admins");

    getRate();

    mAddDriver.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Intent intent = new Intent(AdminActivity.this, AddDriverActivity.class);
            startActivity(intent);
            finish();
            return;
        }
    });

    mEditDriver.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
        }
    });

    mLogout.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Intent intent = new Intent(AdminActivity.this, MainActivity.class);
            startActivity(intent);
            finish();
            return;
        }
    });

    mUpdateRate.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            setRate();
        }
    });
}

private void getRate() {
    mAdminDatabase.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            if (dataSnapshot.exists() && dataSnapshot.getChildrenCount()>0){
                Map<String, Object> map = (Map<String, Object>) dataSnapshot.getValue();
                if (map.get("rate")!=null){
                    mRate = map.get("rate").toString();
                    mRateField.setText(mRate);
                }
            }
        }
        @Override
        public void onCancelled(DatabaseError databaseError) {
        }
    });
}

private void setRate() {
    mRateField.getText().toString();
    mAdminDatabase.child("rate").setValue(mRateField);
}

}

I am sorry, I am still a beginner in Android Studio. Any help would be appreciated. My firebase:

Answer 1

Take a look in your Firebase rules. I saw that you asked for "make the restriction public", so you can open your rules and set read and write true.

Like this:

{
    "rules": {
    ".read": true,
    ".write": true
    }
}

Answer 2

Check the rules in the FirebaseDatabase . If you set them to true , there is no need to auth. Btw, this is a not recommended option, you should always have some security in this aspect.

Hope it helps.

Answer 3

Try this :

mAdminDatabase = FirebaseDatabase.getInstance().getReference("Users").child("Admins");

Should it works :D

If it doesn't work try this :

  mUser = FirebaseDatabase.getInstance().getReference("Users");

and after that, you can set the value of the admins

  mUser.child("Admins").child("rate").setValue("aString");

Answer 4

It's working try this:

private Button mLogout, mAddDriver, mEditDriver, mUpdateRate;

    private DatabaseReference mAdminDatabase;

    private EditText mRateField;

    private String mRate, mPassword;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        mUpdateRate = (Button) findViewById(R.id.save);

        mRateField = (EditText) findViewById(R.id.editText);

        mAdminDatabase = FirebaseDatabase.getInstance().getReference().child("Users").child("Admins");

        getRate();

        mUpdateRate.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                setRate();
            }
        });
    }

    private void getRate() {
        mAdminDatabase.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                if (dataSnapshot.exists() && dataSnapshot.getChildrenCount()>0){
                    Map<String, Object> map = (Map<String, Object>) dataSnapshot.getValue();
                    if (map.get("rate")!=null){
                        mRate = map.get("rate").toString();
                        mRateField.setText(mRate);
                    }
                }
            }
            @Override
            public void onCancelled(DatabaseError databaseError) {
            }
        });
    }

    private void setRate() {
        mRate =   mRateField.getText().toString();
        mAdminDatabase.child("rate").setValue(mRate);
    }

Hope It's help full.