[英]Correct code location to check Firebase if a user has been created already?
[英]Firebase execute code IF child has been created
我有以下代碼用於刪除某些數據形式的Firebase:
public void removeGameFromWaitQueue() {
final DatabaseReference data = FirebaseDatabase.getInstance().getReference().child("games").child(mCurrentGameKey);
data.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot snapshot) {
if (snapshot.exists()) {
mCurrentGame = snapshot.getValue(DatabaseModels.Game.class);
if (mCurrentGame.getState() == DatabaseModels.Game.State.OPEN.ordinal()){
data.removeValue();
}
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
我如何檢查“數據”是否存在,然后執行所有其他代碼? 這意味着,如果我創建DatabaseReference,則代碼有效。 但是,當然,如果我不創建引用,那么我將沒有任何例外。 我應該為此安排2位聽眾嗎? 如果是的話,最好的方法是什么?
為了將來參考,我像這樣解決了它:
public void removeGameFromWaitQueue() {
final DatabaseReference data = FirebaseDatabase.getInstance().getReference().child("games").child(mCurrentGameKey);
data.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot snapshot) {
if (snapshot.exists()) {
mCurrentGame = snapshot.getValue(DatabaseModels.Game.class);
if (mCurrentGame.getState() == DatabaseModels.Game.State.OPEN.ordinal()){
data.removeValue();
}
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
public void removeAfterCheck(){
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
rootRef.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot snapshot) {
if (snapshot.hasChild("games")) {
removeGameFromWaitQueue();
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
也許有更好的方法,但這在我想要的所有情況下都對我有效。
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.