如何比较两个不同的Firebase数据库子数据项

Question

我正在尝试在我的应用程序中实现一项功能，以便如果用户选择一家餐厅，则会显示该餐厅中可用商品的列表，如果没有，则显示一个文本和一个按钮。

我这样处理：我将比较两个子项目，餐厅名称以检查它们是否相等，如果相等，它将显示一个recyclerview以及可用项目列表。

Here's a screenshot of my firebase database

这是我如何保存到FoodRequestRest数据库子级的代码段

requestPlceTxt = placeTxt.getText().toString();  
System.out.println("First instance of Request place her : " + requestPlceTxt);
FirebaseUser user = mAuth.getCurrentUser();
userID = user.getUid();

// String id =  UserReqPlaceRef.push().getKey();
Request request = new Request(requestPlceTxt);
// save to database
UserReqPlaceRef.child("Food Request Restaurant")
               .child(userID)
               .push()
               .setValue(request);

这是我如何检索数据库并将其显示在回收者视图中的代码段

 // Initialize FirebaseAuth
    mFirebaseAuth = FirebaseAuth.getInstance();

    LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
    final RecyclerView recyclerView = (RecyclerView) findViewById(R.id.dummyfrag_scrollableview);

    noItemsTxt = (TextView) findViewById(R.id.no_items);
    OkExitBtn = (Button) findViewById(R.id.ok_exit);
    recyclerView.setLayoutManager(linearLayoutManager);
    recyclerView.setHasFixedSize(true);
    linearLayoutManager.setReverseLayout(true);
    linearLayoutManager.setStackFromEnd(true);
    final List<Donation> donationList = new ArrayList<Donation>();

    final DonationAdapter adapter = new DonationAdapter(donationList, this);

    recyclerView.setAdapter(adapter);

    noItemsTxt.setVisibility(View.GONE);
    OkExitBtn.setVisibility(View.GONE);

    final String curtUserId = FirebaseAuth.getInstance().getCurrentUser().getUid();

    final FirebaseDatabase database = FirebaseDatabase.getInstance();
    DatabaseReference rootRef = database.getReference();

    // get key for each restuarant chosen to make a donation
    final String donateId =   rootRef.child("All Donations").getKey();
    // get key each restuarant chosen to make a request
    final String requestId =   rootRef.child("Food Request Restaurant").child(curtUserId).getKey();

    final Query latestQuery = rootRef
            .child("All Donations")
           // .child(curtUserId)
            .orderByKey()
            .limitToFirst(50);

    final DatabaseReference reqRestLoc = rootRef
            .child("Food Request Restaurant")
            .child(curtUserId)
            .child(requestId);

    // code here to retrieve the string value located at reqRestLoc
    // then compare it with donateRest
    // make another value event listener and get the string?



    latestQuery.addValueEventListener(new com.google.firebase.database.ValueEventListener() {

                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    donationList.clear();

                    for (DataSnapshot gigSnapshot : dataSnapshot.getChildren()) {

                        Donation donation = gigSnapshot
                                .getValue(Donation.class);
                        donationList.add(donation);
                        adapter.notifyDataSetChanged();

                        String donateRest = (String) dataSnapshot
                                .child("All Donaations")
                                .child(donateId)
                                .getValue();
                        Log.d(donateRest, "This is the ");

                        if (s.equals(donateRest)) {   // s is the string value gotten from the restReqLoc
                            recyclerView.setVisibility(View.VISIBLE);
                            noItemsTxt.setVisibility(View.GONE);
                            OkExitBtn.setVisibility(View.GONE);
                            OkExitBtn.setOnClickListener(new View.OnClickListener() {
                                @Override
                                public void onClick(View v) {
                                    DisplayItems.super.onBackPressed();
                                }
                            });
                        }

                        else {
                            recyclerView.setVisibility(View.GONE);
                            noItemsTxt.setVisibility(View.VISIBLE);
                            OkExitBtn.setVisibility(View.VISIBLE);

                        }
                    }
                }
            @Override
            public void onCancelled(DatabaseError databaseError) {
            }
        });

我尝试了比较这两个字符串的不同方法，但是我无法同时访问这两个数据项，这要么是我引用了All Donations的孩子，要么是FoodRequestRestuarant的孩子。有办法吗？