I am trying to make multiple queries to my Firebase database, but it seems I am doing something wrong, and I just can't seem to understand what.
My code is this:
database = FirebaseDatabase.getInstance().getReference();
DatabaseReference ref = database.child("Tbl1");
Query tbl1Query = ref.orderByChild("type");
tbl1Query .addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()) {
for (DataSnapshot singleSnapshot : dataSnapshot.getChildren()) {
Tbl1Item item = singleSnapshot.getValue(Tbl1Item .class);
tbl1List.add(item);
}
DatabaseReference ref = database.child("Tbl2");
Query tbl2Query = ref.orderByChild("status");
tbl2Query.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()) {
for (DataSnapshot singleSnapshot : dataSnapshot.getChildren()) {
tbl2Item item = singleSnapshot.getValue(tbl2Item.class);
tbl2List.add(item);
}
DatabaseReference ref = database.child("Tbl3");
Query tbl3Query = ref.orderByChild("status");
tbl3Query.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()) {
for (DataSnapshot singleSnapshot : dataSnapshot.getChildren()) {
tbl3item item = singleSnapshot.getValue(tbl3item.class);
tbl3List.add(item);
}
SortTableData();
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
The problem is that the app crashes though I get no error in console.
What I am trying to obtain, is create 3 lists of objects with data from table1, table2 and table3 and then call a method that will process that data.
If I remove the 2nd and 3rd queries, everything works fine, but I don't have all the needed data... so what I am doing wrong?
Related
I want to retrieve all the users that have 'request_type: receive' only. How I gonna do that in the android studio? It's for the chat app for request fragment. I want to display in RecyclerView all friend request only.
Image
Check out The query below. It can help you.
Query query = FirebaseDatabase.getInstance().getReference().child("Friend_req").orderByChild("request_type").equalTo("received");
query.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
// Do your job
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
To solve this, you need to loop through your Friend_req node using getChildren() method twice:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference ref = rootRef.child("Friend_req");
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot dSnapshot : dataSnapshot.getChildren()) {
for(DataSnapshot ds : dSnapshot.getChildren()) {
String requestType = ds.child("request_type").getValue(String.class);
if(requestType.equals("receive")) {
Log.d("TAG", "Request received!");
}
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
ref.addListenerForSingleValueEvent(valueEventListener);
I have a database with this schema:
I tested this code but I can't get any msg from the database. I would appreciate your help.
private void Add_Chat(final DataSnapshot dataSnapshot) {
root.child("ChatSpace").addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot snapshot) {
String nom=dataSnapshot.child("ChatSpace").child("msg").getValue(String.class);
System.out.println(nom); //prints "Do you have data? You'll love Firebase."
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
Assuming that ChatSpace is a direct chlid of your Firebase database root, to get all messages please use the following code:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference chatSpaceRef = rootRef.child("ChatSpace");
ValueEventListener eventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String msg = ds.child("msg").getValue(String.class);
Log.d("TAG", msg);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
chatSpaceRef.addListenerForSingleValueEvent(eventListener);
Your output will be:
bbbName
bbbName
Name
If I have a database that is set up like so
-users
-uId0
-Name: "Bill"
-uId1
-Name: "Bob"
-uId2
-Name: "Dave"
How do I get the uId elements if there name child starts with B.
The query should return somthing like this?
-uId0
-Name: "Bill"
-uId1
-Name: "Bob"
Thanks!!
DatabaseReference myReference = FirebaseDatabase.getInstance().getReference();
myReference.child("users").addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
//looping all your users
for (DataSnapshot messageSnapshot:dataSnapshot.getChildren())
{
name = (String)messageSnapshot.child("Name").getValue();
if (name.toLowerCase().contains("b")) {
//u can save your name with 'b' string here
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
To achieve this, please use this code:
DatabaseReference usersRef = FirebaseDatabase.getInstance().getReference().child("users");
usersRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot ds : dataSnapshot.getChildren()) {
String uId = (String) ds.getKey();
DatabaseReference uIdRef = FirebaseDatabase.getInstance().getReference().child("users").child(uId);
uIdRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
String name = (String) dataSnapshot.child("Name").getValue();
if (name.matches("^[B].*$")) {
System.out.println(name);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
throw databaseError.toException(); // don't ignore errors
}
});
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
throw databaseError.toException(); // don't ignore errors
}
});
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 would like to get all the values from my database. But the problem is that I can't make the database reference correct or the for loop of the datasnapshot in order to get all the values. The outcome was always null and without errors.
Here is my code:
databaseReports.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
reportList.clear();
for(DataSnapshot userSnapshot : dataSnapshot.getChildren()){
Reports reports = userSnapshot.getValue(Reports.class);
reportList.add(reports);
}
ReportList adapter = new ReportList(ViewReports.this, reportList);
listViewReports.setAdapter(adapter);
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
I want to get the value of the all the date nodes.
here is my databaseReference
FirebaseDatabase.getInstance().getReference("REPORTS")
Using this produce and empty list because of the referencing.
databaseReports = FirebaseDatabase.getInstance().getReference("REPORTS/05-10-2017");
But this one only shows the data under 05-10-2017
please help me get all the data from sub nodes under REPORTS.TIA
You may try this...
databaseReports.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
reportList.clear();
for(DataSnapshot ymdSnapshot : dataSnapshot.getChildren()){
Log.d("ymdSnapshot", ymdSnapshot.getKey().toString());
for(DataSnapshot repSnapshot : ymdSnapshot.getChildren()){
Reports reports = repSnapshot.getValue(Reports.class);
reportList.add(reports);
}
}
ReportList adapter = new ReportList(ViewReports.this, reportList);
listViewReports.setAdapter(adapter);
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
}
You may try this... partII
databaseReports.child("05-09-2017").addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
reportList.clear();
for(DataSnapshot repSnapshot : dataSnapshot.getChildren()){
Reports reports = repSnapshot.getValue(Reports.class);
reportList.add(reports);
}
ReportList adapter = new ReportList(ViewReports.this, reportList);
listViewReports.setAdapter(adapter);
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
}