Users is my root node, in that I have various childs created by getting the uid of the user who authenticated. Within these childs (uid) their are various childs like Info, General maintenance, Complaints.
I want to show some of the details like gCity, gProductModel from General maintenance child from all the users (uids). Each uid will have a different values of gCity, etc. Under General Maintenance, I want to retrieve all that data by setting it on an adapter and listview.
I am not able to retrieve it.
Database image
retreive code
When i am trying to retrieve data from the current user by using 'getuid()'(As shown below) ,its working fine . But when i try to retrieve all users data using' getkey()' , it isn't working .
user = FirebaseAuth.getInstance().getCurrentUser();
ref= FirebaseDatabase.getInstance().getReference("Users")
.child(user.getUid())
.child("General Maintenance");
ref.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if(list_users.size() > 0)
list_users.clear();
for(DataSnapshot postSnapshot:dataSnapshot.getChildren())
{
Generalperson user =
postSnapshot.getValue(Generalperson.class);
list_users.add(user);
}
if(list_users.size() != 0)
{ ListViewAdapter adapter = new
ListViewAdapter(ServicehistoryActivity.this, list_users);
list_data.setAdapter(adapter);}
else
{
list_data.setVisibility(View.INVISIBLE);
k.setVisibility(View.VISIBLE);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
Please use this code:
DatabaseReference usersRef = FirebaseDatabase.getInstance().getReference().child("Users");
ValueEventListener eventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String userId = ds.getKey();
DatabaseReference userIdRef = FirebaseDatabase.getInstance().getReference().child("Users").child(userId);
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.child("General Maintenence").getChildren()) {
String gCity = ds.child("gCity").getValue(String.class);
String gEmail = ds.child("gEmail").getValue(String.class);
String gPhone = ds.child("gPhone").getValue(String.class);
//and so on
}
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
userIdRef.addListenerForSingleValueEvent(valueEventListener);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
usersRef.addListenerForSingleValueEvent(eventListener);
If you get this error, Listen at /Users failed: DatabaseError: Permission denied is because you are not authorized to the Database, check the Rules Tab in the Realtime database and make this change:
{
"rules": {
".read": true,
".write":true
}
}
Hope it helps.
Related
In practice, people can send requests to each other. What I want to do is to show all the requests sent to one person in that person's profile. I can show all users information with firebase adapter in recyclerview but I could not show only request senders. How can I do? I'd be very happy if you could give an idea to us.
As I understand you want to show the children names of the parent you can use this code.
DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("Friend_req").child("recieved").child("id_of_reciepent");
ValueEventListener eventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String request_sender_id = (String) ds.getKey();
}
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
ref.addListenerForSingleValueEvent(eventListener);
To display the names only of the friends who sent a friend request, you need to query your database twice. Please use the following code in order to achieve this.
String uid = firebaseAuth.getCurrentUser().getUid();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference uidRef = rootRef.child("Friend_req").child("recieved").child(uid);
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String key = ds.getKey();
DatabaseReference userRef = rootRef.child("Users").child();
ValueEventListener eventListener = new ValueEventListener(key) {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot dSnapshot : dataSnapshot.getChildren()) {
String name = dSnapshot.child("Name").getValue(String.class);
Log.d("TAG", name);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
userRef.addListenerForSingleValueEvent(eventListener);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
uidRef.addListenerForSingleValueEvent(valueEventListener);
Your output will be:
Bob
Second Friend
I want to implement followers functionality in my android application. 'First' image refers to the list of user i followed. 'second' image have all ids of all the posts that users post and 'third' image havin post details. all i want to do is to load only the post of those users that i've followed.
What i am doing is, i get emails from followers node and by using indexed recyclerview i load the data but its not working because recyclerview is not getting dynamic reference. Any sugested solution ?
first
second
third
In order to achieve this, you need to query your database for three times like this:
FirebaseUser firebaseUser = firebaseAuth.getCurrentUser();
String userEmail = firebaseUser.getEmail();
String encodedUserEmail = userEmail.replace(".", ",");
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference userEmailFromFollowersRef = rootRef.child("followers").child(encodedUserEmail);
ValueEventListener eventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String followerEmail = ds.getKey();
DatabaseReference my_postsRef = rootRef.child("my_posts").child(followerEmail);
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot dSnapshot : dataSnapshot.getChildren()) {
String postId = dSnapshot.getKey();
DatabaseReference postsRef = rootRef.child("posts").child(postId);
ValueEventListener vel = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot child : dataSnapshot.getChildren()) {
String postText = child.child("postText").getValue(String.class);
Log.d("TAG", postText);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
postsRef.addListenerForSingleValueEvent(vel);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
my_postsRef.addListenerForSingleValueEvent(valueEventListener);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
userEmailFromFollowersRef.addListenerForSingleValueEvent(eventListener);
I have a problem regarding querying the firebase database using a value and getting the specific node. My schema is shown here:
In my schema 'workLocations' belongs to an 'excavationWorks', and 'excavationWorks' belongs to an 'excavationLists'.
That means that the path to a specific workLocation is excavationLists/excavationWorks/workLocations/(specific workLocation)
The problem that I have is that I want to query the workLocations node by the location value (let's say London) and get the parent node (the red circled key which is the key of the specific workLocation).
I have search and read many posts but I haven't managed to make it work.
My code looks like this:
DatabaseReference reference = FirebaseDatabase.getInstance().getReference();
Query query = reference.child("workLocations").orderByChild("location").equalTo("London");
query.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot workLoc : dataSnapshot.getChildren()) {
// do something with the individual "issues"
Log.d(TAG, workLoc.getKey());
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
Thank you
To achieve this, you need to query your database twice like this:
DatabaseReference reference = FirebaseDatabase.getInstance().getReference();
DatabaseReference workLocationsRef = reference
.child("excavationLists")
.child("excavationWorks")
.child("workLocations");
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot dSnapshot : dataSnapshot.getChildren()) {
for(DataSnapshot ds : dSnapshot.getChildren()) {
String key = ds.getKey();
Query query = workLocationsRef.child(key).orderByChild("location").equalTo("London");
ValueEventListener eventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot snapshot) {
String description = snapshot.child("description").getValue(String.class);
Log.d("description", description);
String partentKey = snapshot.getRef().getParent().getKey();
Log.d("partentKey", partentKey);
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
query.addListenerForSingleValueEvent(eventListener);
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
workLocationsRef.addListenerForSingleValueEvent(valueEventListener);
My firebase structure looks like this:
The groups use keys generated by firebase, 0 and 1 are just examples.
In those groups there is more data like "groupname".
How should I retrieve the groupnames of all groups linked to a user?
I'm on Android.
Solved by Alex.
Assuming that the groups node is a direct child of your Firebase root and inside a single group, there is a key named groupName, please use the following code:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference groupsRef = rootRef.child("groups");
ValueEventListener eventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String name = ds.child("name").getValue(String.class);
Log.d("TAG", name);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
Log.d("TAG", task.getException().getMessage()); //Never ignore potential errors!
}
};
groupsRef.addListenerForSingleValueEvent(eventListener);
If you need to be able to get only the group names of the groups that your users are linking to, you need to query twice like this:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference userGroupsRef = rootRef.child("users").child(userKey).child("groups");
ValueEventListener eventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String groupKey = ds.getKey();
DatabaseReference groupKeyRef = rootRef.child("groups").child(groupKey);
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
String name = dataSnapshot.child("name").getValue(String.class);
Log.d("TAG", name);
}
#Override
public void onCancelled(DatabaseError databaseError) {
Log.d("TAG", task.getException().getMessage()); //Never ignore potential errors!
}
};
groupKeyRef.addListenerForSingleValueEvent(valueEventListener);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
Log.d("TAG", task.getException().getMessage()); //Never ignore potential errors!
}
};
userGroupsRef.addListenerForSingleValueEvent(eventListener);
In which userKey is the key of the user from which you want the get the group ids.
So I have a root in the database like this:
users {
"user1" {
username: "username1",
email: "email#email.com"
}
"user2" {
...
}
...
}
Now, I want to register a new user, so for that I need to check if the username that the new user choose is already chosen.
For that I created a single time event and gather all usernames in a string list:
DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("users");
ref.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
List<String> res = new ArrayList<String>();
Iterable<DataSnapshot> users = dataSnapshot.getChildren();
for (DataSnapshot user : users) {
res.add(user.child("username").getValue(String.class));
}
// No way to return anything
}
#Override
public void onCancelled(DatabaseError databaseError) {
//handle databaseError
}
});
But I have a problem, that method is asynchronous. I need to gather all usernames and know if any exists in that list synchronously.
Is there any way to achieve this?