I want to retrieve from firebase database and I already have setup my model to put content in place. I succeeded to retrieve data from one single node but I am unable to do so where I need data from 2 nodes which I want to show it in say Recycler View. However, where I get the success is completely different fragment.
First, I will show you my code for retrieving data from just one node and it is working for me.
Here's the code which is working for one node in different fragment.
Working-Fragment
private void updateArrayList() {
DatabaseReference reference = FirebaseDatabase.getInstance().getReference();
Query query = reference
.child(getString(R.string.dbname_posts))
.child(FirebaseAuth.getInstance().getCurrentUser().getUid());
query.addChildEventListener(new ChildEventListener() {
#Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
data.add(dataSnapshot.getValue(Userpost.class));
adapter.notifyDataSetChanged();
}
Above Code works perfectly.
Now Non-Working Code which doesn't pull anything.
private void updateArrayList() {
DatabaseReference reference = FirebaseDatabase.getInstance().getReference();
Query query = reference
.child(getString(R.string.dbname_posts)).child("profile_photo")
.child(getString(R.string.dbname_user_account_settings))
.child("profile_photo");
query.addChildEventListener(new ChildEventListener() {
#Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
data.add(dataSnapshot.getValue(Userpost.class));
adapter.notifyDataSetChanged();
}
This is a snapshot for firebase database
Firebase Database Snapshot
I made the question as clear as possible on my end.
Thank you all in advance.
To get those values from a specific post, please use the following code:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference postIdRef = rootRef.child("posts").child(postId);
ValueEventListener eventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
String pheading = dataSnapshot.child("pheading").getValue(String.class);
String user_id = dataSnapshot.child("user_id").getValue(String.class);
Log.d("TAG", pheading + " / " + user_id);
DatabaseReference ref = rootRef.child("user_account_settings").child(user_id);
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot ds) {
String profile_photo = ds.child("profile_photo").getValue(String.class);
Log.d("TAG", profile_photo);
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
ref.addListenerForSingleValueEvent(valueEventListener);
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
postIdRef.addListenerForSingleValueEvent(eventListener);
In which postId is the id of the post from which you want to extract the data.
Related
I want to fetch the all uid's of the doctor whose category is "abc"(example) and then store those retrieved uid's into an array list.
I want same results as displayed by the below sql query:
select uid from doctors where category = "abc";
Code for next activity is written below
private void loadDoctors() {
ArrayList<String> uid = getIntent().getStringArrayListExtra("doctor_list");
for (int i =0;i<uid.size();i++){
DatabaseReference doctors = FirebaseDatabase.getInstance().getReference("Doctors").child(uid.get(i));
Adapter = new FirebaseRecyclerAdapter<DoctorModel, DoctorViewHolder>(
DoctorModel.class,
R.layout.doctors_home,
DoctorViewHolder.class,
doctors
) {
#Override
protected void populateViewHolder(final DoctorViewHolder viewHolder, final DoctorModel model, int position) {
viewHolder.doctor_name.setText(model.getName());
Glide.with(Doctors.this).load(model.getProfileimage()).into(viewHolder.doctor_image);
viewHolder.qualification.setText(model.getQualification());
viewHolder.rating.setText(model.getRating());
}
};
Adapter.notifyDataSetChanged();
doctors_list.setAdapter(Adapter);
}
To solve this, please use the following lines of code:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference doctorsRef = rootRef.child("Doctors");
Query categoryQuery = doctorsRef.orderByChild("category").equalTo("Cardiology");
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
List<String> uidList = new ArrayList<>();
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String uid = ds.getKey();
uidList.add(uid);
}
//Do what you need to do with your list
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Log.d("TAG", databaseError.getMessage()); //Don't ignore errors!
}
};
categoryQuery.addListenerForSingleValueEvent(valueEventListener);
At the end, you'll have a list full of uids. One more thing to note, because Firebease API is asynchronous, you will be able to use that list only inside onDataChange() method.
I am trying to read data from Firebase but it is not read by android studio although I am using the tutorial
I tried to copy the link that is sent by Android Studio to Firebase:
DatabaseReference myRef = database.getReference("USERS").child(uID).child("DeviceID");
textview.setText(myRef.toString());
and past the result in the browser and it shows me the result in firebase but when I try to use it to get data it is not retrieving anything.
here is how I am trying to read it by calling a function:
textview.setText(ReadDeviceId);
''''''''''''''''''''''''''''''''''''
private String ReadDeviceId(){
FBUser = FirebaseAuth.getInstance().getCurrentUser();
uID = FBUser.getUid();
FirebaseDatabase database = FirebaseDatabase.getInstance();
DatabaseReference myRef = database.getReference("USERS").child(uID).child("DeviceID");
myRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
r_deviceID = dataSnapshot.getValue(String.class);
}
#Override
public void onCancelled(DatabaseError error) {
// Failed to read value
r_deviceID = "no userID";
}
});
return r_deviceID;
}
'''''''''''''''''''''''''''''''''''''''''''
Knowing that my firebase database security rule is:
'''''''''''''''''''''''''''''''''
{
"rules": {
".write": "auth != null",
".read": true
}
}
'''''''''''''''''''
but nothing is displayed
you can try this code
private String ReadDeviceId(){
FBUser = FirebaseAuth.getInstance().getCurrentUser();
uID = FBUser.getUid();
FirebaseDatabase database = FirebaseDatabase.getInstance();
DatabaseReference myRef =
database.getReference("USERS").child(uID).child("DeviceID");
myRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(Datasnapshot snapshot : dataSnapshot.getChildren)
{
//try to map it with your on model class and replace the String with your model class
r_deviceID = snapshot.getValue(String.class)
}
//r_deviceID = dataSnapshot.getValue(String.class);
}
#Override
public void onCancelled(DatabaseError error) {
// Failed to read value
r_deviceID = "no userID";
}
});
return r_deviceID;
}
In your ReadDeviceId() function, you are returning the value of r_deviceID before it is set (event listeners are not synchronous). Therefore, your textview.setText(ReadDeviceId()); will always be textview.setText(null);, which will show nothing.
For your use case, you should change addValueEventListener to addListenerForSingleValueEvent and set the textview's value from within the handler itself like this:
private String ReadDeviceId(){
FBUser = FirebaseAuth.getInstance().getCurrentUser();
uID = FBUser.getUid();
FirebaseDatabase database = FirebaseDatabase.getInstance();
DatabaseReference myRef = database.getReference("USERS").child(uID).child("DeviceID");
myRef.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
textview.setText(dataSnapshot.getValue(String.class));
}
#Override
public void onCancelled(DatabaseError error) {
// Failed to read value
textview.setText("no userID");
}
});
}
I want to retrieve data for a specific child, how I can write the code? I try a lot, but it did not work:"([ like in my database here how to get the tasks for specific child like lubna and gets all it's child?
Initialize class variables:
private DatabaseReference mDatabase;
mDatabase = FirebaseDatabase.getInstance().getReference();
private DatabaseReference lubnaRef = mDatabase.child("tasks/Lubna");
And then for testing purposes I am assuming you are calling this in your onCreate method of your activity, you'd add the following assuming you do not have a data model for it:
lubnaRef.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
//These are all of your children.
Map<String, Object> lubna = (Map<String, Object>) dataSnapshot.getValue();
for (String childKey: lubna.keySet()) {
//childKey is your "-LQka.. and so on"
//Your current object holds all the variables in your picture.
Map<String, Object> currentLubnaObject = (Map<String, Object>) lubna.get(childKey);
//You can access each variable like so: String variableName = (String) currentLubnaObject.get("INSERT_VARIABLE_HERE"); //data, description, taskid, time, title
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
To solve this, please use the following lines of code:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference lubnaRef = rootRef.child("tasks").child("Lubna");
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String title = ds.child("title").getValue(String.class);
Log.d(TAG, title);
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Log.d(TAG, databaseError.getMessage());
}
};
lubnaRef.addListenerForSingleValueEvent(valueEventListener);
In the same way you get the title, you can also get the other values. The output in your logcat will be:
Homework
//and so on
I'm trying to create a Firebase Realtime database project in which the data stored is either type A or type B, etc. This is how it looks like on the console:
Firebase Database
The user can then add more posts, of which are saved to the database then displayed on a ListView.
My Code
final DatabaseReference room = FirebaseDatabase.getInstance().getReference().getRoot();
chatRoomAdapter = new ArrayAdapter(this, android.R.layout.simple_list_item_1, chatList);
lvChatRoom.setAdapter(chatRoomAdapter);
btnAddChatRoomMa.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
strChatRoomName = etChatRoom.getText().toString();
etChatRoom.setText("");
Map<String, Object> chatMap = new HashMap<>();
chatMap.put(strChatRoomName + " -TYPEA", "");
room.updateChildren(chatMap);
}
});
room.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
Iterator iterator = dataSnapshot.getChildren().iterator();
Set<String> set = new HashSet<>();
while (iterator.hasNext()) {
set.add(((DataSnapshot) iterator.next()).getKey());
}
chatList.clear();
chatList.addAll(set);
chatRoomAdapter.notifyDataSetChanged();
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
I only want to show for instance, TYPEA (on the database), without displaying the rest. How can I achieve this?
If you want to display only the value of the property TYPEA, please use the following code:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference ref = rootRef.child("fruit-TYPEA");
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
String fruitTYPEA = dataSnapshot.getValue(String.class);
Log.d("TAG", fruitTYPEA);
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
ref.addListenerForSingleValueEvent(valueEventListener);
The output will be: orange.
I have this code:
DatabaseReference mdatabase = FirebaseDatabase.getInstance().getReference("allmessages");
mdatabase.child(mAuth.getCurrentUser().getUid()).child(userID).child(uploadID).push().setValue("somevalue");
Then in another class I have this code:
DatabaseReference mdatabase = FirebaseDatabase.getInstance().getReference("allmessages");
mdatabase.child(mAuth.getCurrentUser().getUid()).addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
//Loop through all files in Uploads DataBase
for(DataSnapshot postSnapshot : dataSnapshot.getChildren()){
AllChatMessagesGet allChatMessagesGet = postSnapshot.getValue(AllChatMessagesGet.class);
is it possible for me to get all value under mdatabase.child(mAuth.getCurrentUser().getUid()).child(userID).child(uploadID).push().setValue("somevalue"); by the code I used above.
Because it doesn't retrieve me anything back. I thought that the above code in addValueEventListener would go trough all child classes of mAuth.getCurrentUser().getUid() and retrive me the "somevalue".
But it doesn't. So how do I retrieve "somevalue". Is there any other way? because the codes are written in different classes and I dont know how to get .Child(userID) and .Child(uploadID) it would be problematic for me.
is there anyway for me to retrive all childrens of mdatabase.child(mAuth.getCurrentUser().getUid()) and their values that exist some child below it.
According to your comments, to get those ids that starts with -LD under -LCzWNw0nlC3GKsnPH8B node using only rootRef.child("AllChatMessages").child(uid), please use the followig code:
String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference uidRef = rootRef.child("AllChatMessages").child(uid);
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
for(DataSnapshot dSnapshot : ds.getChildren()) {
for(DataSnapshot snap : dSnapshot.getChildren()) {
String key = snap.getKey();
Log.d("TAG", key);
}
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
uidRef.addListenerForSingleValueEvent(valueEventListener);
The output will be all those ids that you are looking for.
Add and implement a ChildEventListener instead of a ValueEventListener.
Your "somevalue" should be in the DataSnapshot of the overriden onChildChanged method.
I have write up a code glimpse of it is in below code. What I was doing was getting value from the node of users. I have retracted all the children of it by the below code you may also try the same way maybe it would help you.
mFirebaseUserReference = FirebaseDatabase.getInstance().getReference();
userReference = mFirebaseUserReference.child("Users");
childEventListener = new ChildEventListener() {
#Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
Log.d("Values",dataSnapshot+"");
HashMap temp = (HashMap) dataSnapshot.getValue();
if (temp!=null){
if (!temp.get("id").equals(FirebaseAuth.getInstance().getCurrentUser().getUid())){
SignInModel signInModel = new SignInModel();
signInModel.setPhotoUrl((String)temp.get("photoUrl"));
signInModel.setEmail((String)temp.get("email"));
signInModel.setName((String)temp.get("name"));
signInModel.setId((String)temp.get("id"));
arrayList.add(signInModel);
adapter.notifyDataSetChanged();
}
}
}
#Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
}
#Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
}
#Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
};
userReference.addChildEventListener(childEventListener);
Hope that helps.