从firestore检索当前用户数据，并在另一个查询中使用它

Question

我有两个用户admin和faculty。管理员用户可以添加和检索教员数据。管理员isadmin数据库和教员数据库的数据库格式是支持数据库。基本上，我想让管理员访问其部门的教员数据。例如，如果管理员有MCA部门，他只能访问MCA部门的教员信息。

public class userfaculty extends Fragment {
FirebaseFirestore fStore;
private FirebaseAuth fAuth;
RecyclerView mFirestoreList;
FirestorePagingAdapter adapter;
String admindept,adminid;
Query query;
private UserfacultyViewModel mViewModel;
public static userfaculty newInstance() {
return new userfaculty();
}
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
FloatingActionButton fab = view.findViewById(R.id.fabuserfaculty);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(getContext(), AdminAddUserFaculty.class));
}
});
fStore=FirebaseFirestore.getInstance();
fAuth=FirebaseAuth.getInstance();
mFirestoreList=view.findViewById(R.id.RVuserfaculty);
//get current user department
adminid=fAuth.getCurrentUser().getUid();
fStore.collection("Admin").document(adminid).get().addOnSuccessListener(new OnSuccessListener<DocumentSnapshot>() {
@Override
public void onSuccess(DocumentSnapshot documentSnapshot) {
admindept= documentSnapshot.getString("Department");
Log.i("Admindept",admindept);
}
});

'在这里，我想使用检索到的当前用户部门来访问数据'

//divider decoration
DividerItemDecoration dividerItemDecoration=new 
DividerItemDecoration(getContext(),DividerItemDecoration.VERTICAL);
dividerItemDecoration.setDrawable(getResources().getDrawable(R.drawable.recyclerview_divider));
mFirestoreList.addItemDecoration(dividerItemDecoration);
//Query
query = fStore.collection("Faculty").doument("admindept").collection("Teachers");
PagedList.Config config=new PagedList.Config.Builder()
.setInitialLoadSizeHint(10)
.setPageSize(3)
.build();
//RecyclerOptions
FirestorePagingOptions<FacultyModelA> options=new FirestorePagingOptions.Builder<FacultyModelA>()
.setLifecycleOwner(this)
.setQuery(query, config, new SnapshotParser<FacultyModelA>() {
@NonNull
@Override
public FacultyModelA parseSnapshot(@NonNull DocumentSnapshot snapshot) {
FacultyModelA facultyModelA=snapshot.toObject(FacultyModelA.class);
return facultyModelA;
}
})
.build();
adapter=new FirestorePagingAdapter<FacultyModelA, FacultyViewHolder>(options) {
@NonNull
@Override
public FacultyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View v=LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_single_admin_faculty,parent,false);
return new FacultyViewHolder(v);
}

@Override
protected void onBindViewHolder(@NonNull FacultyViewHolder holder, int position, @NonNull FacultyModelA model) {
holder.list_name.setText(model.getName());
}
@Override
protected void onLoadingStateChanged(@NonNull LoadingState state) {
super.onLoadingStateChanged(state);
switch (state){
case LOADING_INITIAL:
Log.d("PAGING_LOG","All inintial data");
break;
case LOADING_MORE:
Log.d("PAGING_LOG","All next page");
break;
case FINISHED:
Log.d("PAGING_LOG","All data loaded");
break;
case ERROR:
Log.d("PAGING_LOG","Error Loading Data");
break;
case LOADED:
Log.d("PAGING_LOG","Total Item Loaded: "+getItemCount());
break;
}
}
};
mFirestoreList.setHasFixedSize(true);
mFirestoreList.setLayoutManager(new LinearLayoutManager(getContext()));
mFirestoreList.setAdapter(adapter);
}
class FacultyViewHolder extends RecyclerView.ViewHolder{
private TextView list_name;
public FacultyViewHolder(@NonNull View itemView) {
super(itemView);
list_name=itemView.findViewById(R.id.list_fname);
}
}
}

"但在这一行，我得到了一个空指针Exception">

query = fStore.collection("Faculty").doument(admindept).collection("Teachers");

我应该做什么改变…提前谢谢你。

Answer 1

您的文档名称在代码中是"admindept"，但在屏幕截图中是"MCA"。解决这个问题，你就可以开始工作了。