[英]How to retrieve data from firebase database
我一直在使用Android和Firebase創建移動應用程序,無法從firebase獲取數據,問題出在Survey survey = ds.getValue(Survey.class);
,僅當我刪除屬性選項和時間戳時才起作用,這是我的代碼:
private FirebaseDatabase firebaseDatabase=FirebaseDatabase.getInstance();
private DatabaseReference mRootReference=firebaseDatabase.getReference();
private DatabaseReference mSurveysReference=mRootReference.child("surveys");
mSurveysReference.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
for (DataSnapshot ds:dataSnapshot.getChildren()){
Survey survey = ds.getValue(Survey.class);
surveys.add(survey);
}
}
@Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
}
});
public class Survey {
public boolean acceptAnonymousVotes;
public boolean enabled;
public String id;
public String image;
public Option[] options ;
public boolean resultPublic;
public Timestamp timeStamp;
public String title;
public int totalComments;
public int totalViews;
public int totalVotes;
public String type;
public String userId;
public Survey() {
}
}
public class Option {
public int id ;
public String title ;
}
根據https://firebase.google.com/docs/database/android/read-and-write ,您需要一個默認構造函數,該構造函數是調用DataSnapshot.getValue(XY.class)所必需的
也可以使用List<Option>
代替Options[]
作為選項。
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