I'm building a social app. I need to display friends posts in the main feed with firebase recycler adapter. I've tried many options but I'm not been able to do this, with the code below I'm only able to load posts of the current user. I'm pasting the code here please guide me in this regard.
I'm using 2 queries one for friends and other for posts
The two database references are as follows
mUsersPostsDatabase = FirebaseDatabase.getInstance().getReference().child("posts");
mFriendsDatabase= FirebaseDatabase.getInstance().getReference().child("Friends").child(current_user_id);
The method is as follows
#Override
protected void onStart() {
super.onStart();
Query posts = mUsersPostsDatabase
.orderByChild("user_id")
.equalTo(mFriendsDatabase.getKey());
FirebaseRecyclerAdapter<CurrentUserPosts, UsersViewHolder> firebaseRecyclerAdapter =
new FirebaseRecyclerAdapter<CurrentUserPosts, UsersViewHolder>(
CurrentUserPosts.class,
R.layout.view_user_post_layout,
UsersViewHolder.class,
posts
) {
#Override
protected void populateViewHolder(UsersViewHolder usersViewHolder, CurrentUserPosts model, int position) {
usersViewHolder.setImage_url(model.getImage_url(), getApplicationContext());
usersViewHolder.setUser_image(model.getUser_image(), getApplicationContext());
usersViewHolder.setUser_name(model.getUser_name());
usersViewHolder.setDate_time(model.getDate_time());
usersViewHolder.setDescription(model.getDescription());
}
};
mUsersList.setAdapter(firebaseRecyclerAdapter);
}
The database node are like the following
Friends ---> current_user_id ----> friend_id
Posts ----> post_id ----> date, user_id, image_url, descp......
Query friends = FirebaseDatabase.getInstance().getReference().child("Friends").child(mAuth.getCurrentUser().getUid());
friends.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot ds : dataSnapshot.getChildren()) {
String friendID = ds.getRef().getKey().toString();
Query posts = FirebaseDatabase.getInstance().getReference()
.child("posts").orderByChild("user_id").equalTo(friendID);
posts.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot singleSnapshot : dataSnapshot.getChildren()) {
CurrentUserPosts newPost = new CurrentUserPosts();
newPost.setImage_url(singleSnapshot.child("image_url").getValue(String.class));
mPosts.add(newPost);
}
Collections.reverse(mPosts);
mUsersList.setAdapter(new UsersPostsThumbAdapter(mPosts));
}
#Override
public void onCancelled(DatabaseError databaseError) {
String errormsg = databaseError.toString();
Toast.makeText(getApplicationContext(), errormsg, Toast.LENGTH_SHORT).show();
}
});
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
Related
I just started to learn Android Studio, and I am trying to make a search activity that can search for a data from my firebase database. But whenever I try to search no result shows up on the screen and does not retrieve any data from the database. Can anyone solve the problem? Thanks.
private void searchForMatch(final String keyword) {
Log.d(TAG, "searchForMatch: searching for a match: " + keyword);
imageDTOs.clear();
if(keyword.length() == 0) {
} else {
DatabaseReference reference = FirebaseDatabase.getInstance().getReference();
Query query = reference.child("books").orderByChild("title").equalTo(keyword);
query.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
for(DataSnapshot singleSnapshot : dataSnapshot.getChildren()) {
Log.d(TAG, "onDataChange: found book:" + singleSnapshot.getValue(ImageDTO.class).toString());
imageDTOs.add(singleSnapshot.getValue(ImageDTO.class));
}
searchAdapter = new SearchAdapter(SearchActivity.this, R.layout.item_library, imageDTOs);
listView.setAdapter(searchAdapter);
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
}
}
While displaying the recent chats fragment in the application I am fetching my chats from firebase and filtering out the chats by their receiverID and senderID in the chat object to display the recent chats.
The problem says ConcurrentModificationException in ArrayList and it looks like due to the complexity of searching id in the array it occurred, I need a solution to minimize this chat filteration complexity.
// private List<String> stringList; Declaration at top
stringList = new ArrayList<>();
firebaseUser = FirebaseAuth.getInstance().getCurrentUser();
databaseReference = FirebaseDatabase.getInstance().getReference("BaatCheet/Chats/");
databaseReference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
//userModelList.clear();
for (DataSnapshot dataSnapshot1 : dataSnapshot.getChildren()) {
MessageModel messageModel = dataSnapshot1.getValue(MessageModel.class);
if (messageModel.getSender().equals(firebaseUser.getUid())){
stringList.add(messageModel.getReceiver());
}
if (messageModel.getReceiver().equals(firebaseUser.getUid())){
stringList.add(messageModel.getSender());
}
}
readChat();
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
The read chat function
private void readChat() {
userModelList = new ArrayList<>();
databaseReference = FirebaseDatabase.getInstance().getReference("BaatCheet/Users/");
databaseReference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
userModelList.clear();
for (DataSnapshot dataSnapshot1 : dataSnapshot.getChildren()){
UserModel userModel = dataSnapshot1.getValue(UserModel.class);
for (String id: stringList){
if (userModel.getId().equals(id)){
if (userModelList.size() !=0){
for (UserModel userModel1 : userModelList){
if (!userModel.getId().equals(userModel1.getId())){
userModelList.add(userModel);
Log.d("DataAdded",userModel.getId());
} // If the existing list don't have same value for sender and reciever
} // end of inner userModel
} else {
userModelList.add(userModel);
Log.d("DataAdded",userModel.getId());
} // end of else
} // end of userModel id equals string id
} // end of String is loop
} // end of DataSnapshot loop
usersAdapter = new UsersAdapter(userModelList);
recyclerView.setAdapter(usersAdapter);
} // end of onDataChange
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
}// end of readChat()
The results would be the recyclerView of recent chats containing the chats which contain messages either send by the sender or receiver to each other.
In the following snippet of code :
for (UserModel userModel1 : userModelList){
if (!userModel.getId().equals(userModel1.getId())){
userModelList.add(userModel);
Log.d("DataAdded",userModel.getId());
} // If the existing list don't have same value for sender and reciever
} //
You are modifying userModelList while iterating through userModelList. This is not allowed and is the cause of ConcurrentModificationException.
There are few ways to simplify the logic, the simplest (albeit not the best) would be to convert this foreach loop into a simple for i loop.
for (int i = 0; i< userModelList.size(); i++) {
UserModel userModel1 = userModelList.get(i);
if (!userModel.getId().equals(userModel1.getId())){
userModelList.add(userModel);
Log.d("DataAdded",userModel.getId());
} // If the existing list don't have same value for sender and reciever
} //
Basically to handle this complexity I am now using separate nodes just for storing the chatLists as such now I don't need to read chats for filtering the recent chats.
The below code is for creating a new node everytime user sends a message it will update the node if the recieverID is different.
dbrefChatList = FirebaseDatabase.getInstance().
getReference("BaatCheet/ChatList/")
.child(senderuserID)
.child(receiveruserID);
dbrefChatList.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
if (!dataSnapshot.exists()){
dbrefChatList.child("id").setValue(receiveruserID);
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
As such ChatList is a Model Class which contains single String called "id" and this id will be used to search in the node.
The below code is for the ChatFragment which fetches the chatList from firebase and set the data to recycler view.
// private List<ChatList> chatList; Declaration at top
chatListList = new ArrayList<>();
firebaseUser = FirebaseAuth.getInstance().getCurrentUser();
databaseReference = FirebaseDatabase
.getInstance()
.getReference("BaatCheet/ChatList")
.child(firebaseUser.getUid());
databaseReference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
chatListList.clear();
for (DataSnapshot snapshot : dataSnapshot.getChildren()){
ChatList chatList = snapshot.getValue(ChatList.class);
chatListList.add(chatList);
}
myChatList();
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
The function myChatList act as the function of readChat in the problem statement.
private void myChatList() {
userModelList = new ArrayList<>();
databaseReference = FirebaseDatabase.getInstance().getReference("BaatCheet/Users/");
databaseReference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
userModelList.clear();
for (DataSnapshot snapshot : dataSnapshot.getChildren()){
UserModel userModel = snapshot.getValue(UserModel.class);
for (ChatList chatList : chatListList){
if (userModel.getId().equals(chatList.getId())){
userModelList.add(userModel);
}
}
}
usersAdapter = new UsersAdapter(userModelList);
recyclerView.setAdapter(usersAdapter);
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
}
You can set a flag while traversing the array, after it's done, add it if it doesn't exist yet:
// Display 1 user from chats
for (String id : str_usersList) {
if (user.getId().equals(id)) {
if (userList.size() != 0) {
boolean exists = false;
// If not exists then add
for (User user1 : userList) {
if (user.getId().equals(user1.getId())) {
exists = true;
}
}
if (!exists) {
userList.add(user);
}
} else {
userList.add(user);
}
}
}
I am using firebase auth ui in order to create users with mail and password but after the registration I forward them to a new activity in order to choose I username which needs to be unique. My idea was to search the whole DB in order to see if that username exists already or not. Here is how I am trying to do this but no luck till now:
submitBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Log.d("UserName", "Click: ");
DatabaseReference mDatabase = FirebaseDatabase.getInstance().getReference("USERS");
mDatabase.orderByChild("username").equalTo("name1").addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot snapshot: dataSnapshot.getChildren()) {
//Here you can get all data
Log.d("UserName", "onDataChange: "+snapshot.toString());
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
});
I have also tried this one:
submitBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Log.d("UserName", "Click: ");
DatabaseReference mFirebaseDatabaseReference = FirebaseDatabase.getInstance().getReference();
Query query = mFirebaseDatabaseReference.child("USERS").orderByChild("username").equalTo("name1");
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
//TODO get the data here
Log.d("UserName", "onDataChange: " + dataSnapshot.toString());
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
};
query.addValueEventListener(valueEventListener);
}
});
The only reason your code is not working is because "username" is not a direct child of the USERS table.
Your direct children will have random ids , which you can iterate trough with ChildEventListener like this:
DatabaseReference mDatabase = FirebaseDatabase.getInstance().getReference("USERS");
mDatabase.addChildEventListener(new ChildEventListener() {
#Override
public void onChildAdded(DataSnapshot dataSnapshot, String previousChildName) {
User user = dataSnapshot.getValue(User.class); // pojo
if(user.getUsername().equals("name1") {
// do something
}
}
...
)
A simple question:
Referring to my database image, I want to get the values of the children of node "user" in a list in an Activity, i.e. values "a" and "m" should be displayed in the list.
What should I use and how?
Please try this code:
DatabaseReference yourRef = FirebaseDatabase.getInstance().getReference().child("user");
yourRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
List<String> usersList = new ArrayList<>();
for (DataSnapshot ds : dataSnapshot.getChildren()) {
String userName = (String) ds.getKey();
usersList.add(userName);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
throw databaseError.toException(); // don't ignore errors
}
});
This is the way in which you'll have in your list, a, m ans so on.
Hope it helps.
You can get the info from the docs here
List<User> allUsers = new ArrayList<>();
DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("user");
ref.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
allUsers.clear();
for (DataSnapshot userSnapshot: dataSnapshot.getChildren()) {
allUsers.add(userSnapshot.getValue(User.class));
}
yourRecyclerViewAdapter.notifyDataSetChanged();
}
#Override
public void onCancelled(DatabaseError databaseError) {
// Getting Users failed, log a message
Log.w(TAG, "loadUser:onCancelled", databaseError.toException());
// ...
}
});
I want to get item in the last node added in firebase database from my Android. You can see on the image below i'm not sure how to get the specific node, because unique key is created by Firebase. How to reference to auto-created node and child inside? Thanks a lot
The last node
Try this:
DatabaseReference databaseReference = FirebaseDatabase.getInstance().getReference();
Query lastQuery = databaseReference.child("mp").orderByKey().limitToLast(1);
lastQuery.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
String message = dataSnapshot.child("message").getValue().toString();
}
#Override
public void onCancelled(DatabaseError databaseError) {
// Handle possible errors.
}
});
Hope this helps!
This might work:
DatabaseReference db = FirebaseDatabase.getInstance().getReference().child("mp");
Query query = db.orderByKey().limitToLast(1);
query.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot child: dataSnapshot.getChildren()) {
Log.d("User key", child.getKey());
Log.d("User val", child.child("message").getValue().toString());
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
// TODO: Handle errors.
}
});
I prefer to write and retrieve data through objects.
MyObject is POJO.
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot data : dataSnapshot.getChildren()) {
MyObject myObject = data.getValue(MyObject.class);
Log.i(TAG, data.getKey() + " = " + myObject.toString());
}
}
console.log('last messages', messages[messages.length-1]);