问题
Below is the code I implemented which works but its assigning the last Firebase child 'PoolName' and 'PoolId' to all three (3) results when they should be different!?
playerInPoolReference = mFirebaseDatabase.getReference("PlayerInPool").child(userID);
playerInPoolReference.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
if(dataSnapshot.exists()) {
for (DataSnapshot poolSnapshot : dataSnapshot.getChildren()) {
String poolID = poolSnapshot.getKey();
poolReference = mFirebaseDatabase.getReference("Pools").child(poolID);
poolReference.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot snapShot) {
if (snapShot.exists()) {
pID = snapShot.getKey();
String gameID = snapShot.child("GameId").getValue().toString();
//
pName = snapShot.child("PoolName").getValue().toString();
gameReference = mFirebaseDatabase.getReference("Games").child(gameID);
gameReference.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot snap) {
if (snap.exists()) {
Pools pool = snap.getValue(Pools.class);
pool.setPoolId(pID);
pool.setPoolName(pName);
//
poolList.add(pool);
adapter = new PoolAdapter(getActivity(), poolList);
recyclerView.setAdapter(adapter);
}
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
}
});
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
} // End for loop
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
Does anyone know or have they implemented a solution where I wish to get the list of Groups (ex. Pools in my case) that a particular user is in?
In my case I check for the pools that the player is in, then need to access the Pool Node to get the Pool info, which included the particular game id , and then lastly get the associated Game info so that I can display to the player.
The Firebase structure is as follows:
Users
userId1
userName : peter
userId2
userName : john
Pools
poolId1
poolName: pool1
etc....
poolId2
poolName: pool2
Games
1000
gameName: game1
1001
gameName: game2
PlayerInPool
UserId
12345: true
54321: true
etc...
UserId:
12345: true
The ISSUE is that it sets the following:
pool.setPoolId(pID);
pool.setPoolName(pName);
to the last values in the list of pools!?
回答1:
Users
userId1
userName : peter
userId2
userName : john
Pools
poolId1
poolName : pool1
poolId2
poolName : pool2
Games
gameId1
gameName : game1
gameId2
gameName: game2
UserPool
poolId1
userName: peter
poolId2
userName: john
GamePool
gameId
poolId: poolId1
gameName : game1
You can do the following database, parent node including Users, Pools, and Games. Then you can do two nodes, one called UserPool that can include each all the users that are in each pool, and the other called GamePool that can include game name and pool info.
FirebaseDatabase database = FirebaseDatabase.getInstance();
DatabaseReference userReference = database.getReference("UserPool");
DatabaseReference gameReference = database.getReference("GamePool");
userReference.orderByKey().equalTo(poolId).addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds: dataSnapshot.getChildren()){
String keyPool = ds.getKey();
String userId = ds.child("userName").getValue().toString();
gameReference.orderByChild("poolId").equalTo(keyPool).addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot datas : dataSnapshot.getChildren()){
String gameId = datas.getKey();
String gameName = datas.child("gameName").getValue().toString();
}
}
@Override
public void onCancelled(DatabaseError databaseError) {}
});
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
Here you put the reference at child UserPool and retrieve the poolId and the userNames, you can also add other info and retrieve them here.
Then you use a nested valueEventListener that refers to the node gamePool and using the key that you retrieved (which is the poolId), you create a query andorderByChild("poolId").equalTo(keyPool) and retrieve the game name, and other info that you can add there like game info...
来源：https://stackoverflow.com/questions/55433036/having-issue-retrieving-correct-information-from-firebase-with-multiple-lookups