android - 获取 Firebase 数据库中所有包含用户 id 的子项

Question

我试图通过搜索 firebase 数据库并匹配接收方节点下的用户 ID 来显示当前用户的所有好友请求，但一直不返回任何内容。如何在接收方节点中按用户 ID 进行过滤？

    public void searchForPendingFriendRequests(){
    mUserFriendsReference = mFirebaseDatabase.getReference("friend_request/receiver" + FirebaseAuth.getInstance().getCurrentUser().getUid());
    mUserFriendsReference.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            if(dataSnapshot.getChildrenCount() != 0) {
                mPendingFriendsCard.setVisibility(View.VISIBLE);
                mAllRequestsText.setVisibility(View.VISIBLE);

                for(DataSnapshot child: dataSnapshot.getChildren()) {
                    FriendRequest friendRequest = child.getValue(FriendRequest.class);
                    friendToAdd = friendRequest.getSender();
                    populateCurrentAddFriendData(friendRequest);
                    break;
                }
            }
        }
        @Override
        public void onCancelled(DatabaseError databaseError) {}
    });
}

db 看起来像这个 friend_request ---> {pushid} ---> receiver ---> userid

Answer 1

我想你忘了在 mUserFriendsReference
中添加这个 "/" 改变这一行

  mUserFriendsReference = mFirebaseDatabase.getReference("friend_request/receiver" +FirebaseAuth.getInstance().getCurrentUser().getUid());

对此

  mUserFriendsReference =mFirebaseDatabase.getReference("friend_request/receiver/" +FirebaseAuth.getInstance().getCurrentUser().getUid());