so i am stuck. i want to retrieve child of child from my firebase database.
my database struture looks like this
users{
user1{
name:
regno:
carmodel:
caryear}
user2{
name:
regno:
carmodel:
caryear}
user3{
name:
regno:
carmodel:
caryear}}
Regno = car registration number.
when i type in a "carreg no" and press ok. i want the code to search every carreg. if a match is found execute next set of codes.
so far i have tried to store it in a array. but the code seems to fail when i put reg or any variable name that exist.
public void input(){
FirebaseDatabase firebase = FirebaseDatabase.getInstance();
final DatabaseReference table_user = firebase.getReference("User");
table_user.addListenerForSingleValueEvent(
new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
//Get map of users in datasnapshot
collectPhoneNumbers((Map<String,Object>) dataSnapshot.getValue());
}
#Override
public void onCancelled(DatabaseError databaseError) {
//handle databaseError
}
});
private void collectPhoneNumbers(Map<String,Object> users) {
ArrayList<Long> phoneNumbers = new ArrayList<>();
//iterate through each user, ignoring their UID
for (Map.Entry<String, Object> entry : users.entrySet()){
//Get user map
Map singleUser = (Map) entry.getValue();
//Get phone field and append to list
phoneNumbers.add((Long) singleUser.get("namesd"));
}
System.out.println(phoneNumbers.toString());
mVoiceInputTv.setText("" + phoneNumbers);
}
}
i got this from another stackflow. before this i tried creating a for look. it was successfull but result failed 80% of the time. (not always correct).
To solve this, you need to query your database using orderByChild() method like this:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference usersRef = rootRef.child("users");
Query regnoQuery = usersRef.orderByChild("regno").equalsTo(regno);
In which regno argument from equalsTo() is the the actual registration number that you are looking for. Then attach a listener to the regnoQuery and use getChildrenCount() method on the dataSnapshot object. If the number of childrens is noOfChildrens > 0 then execute the set of codes you need.
private FirebaseDatabase mdatabase;
private DatabaseReference mdatabaseRef;
mdatabase = FirebaseDatabase.getInstance();
mdatabaseRef = mdatabase.getReference();
mdatabaseRef.child("users").child("users1").orderByChild("regno").equalsTo(regno).addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot childSnapshot : dataSnapshot.getChildren()) {
}
}
Related
In Firebase Realtime Database on Android, I want to retrieve this id "-Mb1sSv-FCNr9ElxZIwN".
databaseReference = FirebaseDatabase.getInstance().getReference().child("Registration Data1");
mDBListener = databaseReference.orderByKey().limitToLast(1).addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
mTeachers.clear();
for (DataSnapshot teacherSnapshot : dataSnapshot.getChildren()) {
Data DB = teacherSnapshot.getValue(Data.class);
DB.setKey(teacherSnapshot.getKey());
mTeachers.add(DB);
}
mAdapter.notifyDataSetChanged();
mProgressBar.setVisibility(View.GONE);
}
It looks to me that KAsr ... dhz1 is the user ID that comes from the authentication process. If so, that UID should also be added to your reference. So to be able to get this id "-Mb1sSv-FCNr9ElxZIwN", please change the following reference:
databaseReference = FirebaseDatabase.getInstance().getReference().child("Registration Data1");
To:
String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
databaseReference = FirebaseDatabase.getInstance().getReference().child("Registration Data1").child(uid);
Meaning that:
DB.setKey(teacherSnapshot.getKey());
Will set the above key to the "DB" object.
What is the proper way to read data from Firebase Realtime Database? I have created a database "Mybill"s with child bills. In child Bills, I am saving UserId from FirebaseAuth so it should be easy to find bills for a specific user and in userID child, I have a child that I have created using the .push() method and in that, I have data about the bill.
It looks like this:
How should I change my Java code so I can get all the bills saved for a specific user (the user that is currently logged in)
this is my code for now :
final FirebaseDatabase database = FirebaseDatabase.getInstance();
DatabaseReference ref = database.getReference("bills");
Query checkUser = ref.orderByChild("UserId").equalTo(Autentication.GetUser());
// Attach a listener to read the data at our posts reference
checkUser.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
String email = dataSnapshot.child("email").getValue(String.class);
String market = dataSnapshot.child("market").getValue(String.class);
String price = dataSnapshot.child("price").getValue(String.class);
String date = dataSnapshot.child("date").getValue(String.class);
}
#Override
public void onCancelled(DatabaseError databaseError) {
System.out.println("The read failed: " + databaseError.getCode());
}
});
How should I change my Java code so I can get all the bills saved for a specific user (the user that is currently logged in)
To do that, please use the following lines of code:
String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference uidRef = rootRef.child("bills").child(uid);
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String email = ds .child("email").getValue(String.class);
String market = ds .child("market").getValue(String.class);
String price = ds .child("price").getValue(String.class);
Log.d("TAG", email + "/" + market + "/" + price);
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Log.d("TAG", databaseError.getMessage()); //Don't ignore potential errors!
}
};
uidRef.addListenerForSingleValueEvent(valueEventListener);
The "date" cannot be read as a String, as it's an object. So the most appropriate way would be to read it as a Map<String, Object>. In this way, you are getting only the bills that correspond to a specific user (logged-in user).
I am working with firebase database and i was trying to get the value of a child using this code below and may System.out.println(MyCredit.toString()); is always returns null: Please see my firebase database
DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("Users");
ref.addListenerForSingleValueEvent(
new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
//Get map of users in datasnapshot
CollectCredits((Map<String,Object>) dataSnapshot.getValue());
}
#Override
public void onCancelled(DatabaseError databaseError) {
//handle databaseError
}
});
private void CollectCredits(Map<String,Object> users) {
MyCredit = new ArrayList<>();
//iterate through each user, ignoring their UID
for (Map.Entry<String, Object> entry : users.entrySet()){
//Get user map
Map singleUser = (Map) entry.getValue();
//Get Credit field and append to list
MyCredit.add((Long) singleUser.get("Credit"));
Toast.makeText(MainActivityCustonlistViewnew.this, "Credit : " +String.valueOf(MyCredit), Toast.LENGTH_SHORT).show();
}
System.out.println(MyCredit.toString());
}
Try this:
private void CollectCredits(DataSnapshot dataSnapshot) {
MyCredit = new ArrayList<>();
//iterate through each dataSnapshot
for (DataSnapshot d1 : dataSnapshot.getChildren()){
MyCredit.add(d1.getValue());
}
}
Let me give you some suggestions, Try to check your firebase database path both the root and child path because some time you did everything correctly but the path you specified to your Database reference which is not referring to the correct path. So it can produce the same result what are getting right now.
I have app and I am using Firebase Realtime database. I need get all data from Search and using this code:
myRef = FirebaseDatabase.getInstance().getReference();
Query query = myRef.orderByChild("Search");
query.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
GenericTypeIndicator<ArrayList<String>> t = new GenericTypeIndicator<ArrayList<String>>(){};
test2 = dataSnapshot.getValue(t);
I need to get it all in ArrayList, but now i am getting below exception
com.google.firebase.database.DatabaseException: Expected a List while
deserializing, but got a class java.util.HashMap
Database structure:
How can I fix this? I need to get all data from Search in ArrayList.
If you need I can post all code from activity and logs.
Json:
{
"Search" : [ "Eggs", "Milk", "Apples", "Carrot", "Sugar", "Potato" ]
}
Assuming that the object node is a direct child of your Firebase database root, to solve this, please use the following code:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference searchRef = rootRef.child("object").child("Search");
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
List<String> list = new ArrayList<>();
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String value = ds.getValue(String.class);
list.add(value);
}
Log.d("TAG", list.toString());
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
searchRef.addListenerForSingleValueEvent(valueEventListener);
The output will be:
Eggs
Milk
Apples
Carrot
Sugar
Potato
For example, there are 2 main nodes in my database (there can be more). The parent node is the user's authentication id and inside it
there is some detail as you can see.
I am trying to do that if any user login all other user's data populated on his activity
but I really don't know how to start because every user has its own authentication id and there are sub-nodes also like map location and image
How can I fetch every user's detail to the activity?
What you can do is that get the data from the fbuserinfo node using an event listener like this and iterate through the data. Here User.class is the class for the User model that you have created
DatabaseReference userDataReference = FirebaseDatabase.getInstance().getReference()
.child("fbuserinfo");
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot ds : dataSnapshot.getChildren()) {
User user = ds.getValue(User.class);
Log.d("User", user);
}
}
}
#Override
public void onCancelled (DatabaseError databaseError){
Log.d(TAG, "Error fetching user data - " + databaseError.getMessage());
}
}
userDataReference.addListenerForSingleValueEvent(eventListener);
And then if you want to display the data, you can do it in the for loop and have an if condition to check if the user is not equal to the current one
Using the following example you'll be able to log the name of all users from your database.
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference fbRef = rootRef.child("Users").child("fbusersinfo");
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) {}
};
fbRef.addListenerForSingleValueEvent(eventListener);
The output will be:
Ahmend Abbas
mahanoor 4
If you need also the other properties, you can get them in the same manner.