Firebase UI:解决方案是从子节点接收所有键，并使用它从另一个节点接收信息并将其填充到Recyclerview中？

Question

我正在寻找一种解决方案，从我的孩子“药物”中获取数据，并使用I从"medication_plan“节点接收特定数据，并将其显示在回收视图中。

DB-Structure：

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目前，我正在使用Firebase UI填充我的Recyclerview

private DatabaseReference mRef;

private RecyclerView mRecyclerView;
private RecyclerView.LayoutManager mLayoutManager;
private FirebaseRecyclerAdapter<Medication,MedicationViewHolder> mAdapter;

List<User> items = new ArrayList<>();

User user = new User();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mRecyclerView = findViewById(R.id.my_recycler_view);
    mRecyclerView.setHasFixedSize(true);

    mLayoutManager = new LinearLayoutManager(this);
    mRecyclerView.setLayoutManager(mLayoutManager);

    setData();
}

private void setData() {
    Query query = FirebaseDatabase.getInstance().getReference().child("Medication_plan");
    FirebaseRecyclerOptions<Medication> options = new FirebaseRecyclerOptions.Builder<Medication>()
            .setQuery(query,Medication.class)
            .build();

    mAdapter = new FirebaseRecyclerAdapter<Medication, MedicationViewHolder>(options) {
        @Override
        protected void onBindViewHolder(@NonNull MedicationViewHolder holder, int position, @NonNull Medication model) {
            final Medication tempmed = new Medication(model.getDr()
                    ,model.getMedicine()
                    ,model.getDate()
                    ,model.getComment());

            holder.mDoctor.setText(model.getDr());
            holder.mMedicine.setText(model.getMedicine());
            holder.mDate.setText(model.getDate());
        }

        @NonNull
        @Override
        public MedicationViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
            View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.my_text_view,viewGroup,false);
            MedicationViewHolder vh = new MedicationViewHolder(v);
            return vh;
        }
    };

    mRecyclerView.setAdapter(mAdapter);
}

@Override
protected void onStart() {
    mAdapter.startListening();
    super.onStart();
}

@Override
protected void onStop() {
    mAdapter.stopListening();
    super.onStop();
}

当我使用这段代码时，我得到了每个用药计划，但我只想要用户的具体计划。

Answer 1

添加此函数以获取数据：

ArrayList<String> list = new ArrayList<String>();
DatabaseReference ref= FirebaseDatabase.getInstance().getReference("User").child("R3").child("medication");
ref.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for (DataSnapshot snap: dataSnapshot.getChildren()) {
            list.add(snap.child("id").getValue(String.class));
        }
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {
        Log.w(TAG, "onCancelled", databaseError.toException());
    }
});

在此之后，添加以下代码以获取第二个数据信息：

ArrayList<String> listOfSomething = new ArrayList<String>();
DatabaseReference ref=  FirebaseDatabase.getInstance().getReference("Medication_plan");
ref.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for (String s: list) {
            listOfSomething.add(dataSnapshot.child("s").child("comment").getValue(String.class));
        }
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {
        Log.w(TAG, "onCancelled", databaseError.toException());
    }
});

在我的示例中，我检索注释。您可以在想要检索的任何内容中对其进行更改。

Answer 2

要仅获取对应于特定用户的药物，您需要查询数据库两次。一次获取药品in，第二次获取药品的详细信息，如以下代码行所示：

DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference medicationRef = rootRef.child("User").child("r3").child("medication");
ValueEventListener valueEventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for(DataSnapshot ds : dataSnapshot.getChildren()) {
            String medicationKey = ds.getKey();

            DatabaseReference medicationKeyRef = rootRef.child("Medication_plan").child(medicationKey);
            ValueEventListener eventListener = new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    for(DataSnapshot ds : dataSnapshot.getChildren()) {
                        Medication medication = ds.getValue(Medication.class);
                        Log.d(TAG, medication.getMedicine());
                    }
                }

                @Override
                public void onCancelled(@NonNull DatabaseError databaseError) {
                    Log.d(TAG, databaseError.getMessage()); //Don't ignore errors!
                }
            };
            medicationKeyRef.addListenerForSingleValueEvent(eventListener);
        }
    }

    @Override
    public void onCancelled(@NonNull DatabaseError databaseError) {
        Log.d(TAG, databaseError.getMessage()); //Don't ignore errors!
    }
};
medicationRef.addListenerForSingleValueEvent(valueEventListener);

logcat中的输出将为：

Aspirin
Paracetamol

除此之外，您还应该简化User节点，如以下模式所示：

Firebase-root
   |
   --- User
        |
        --- R3
            |
            --- lastname: "Hirsch"
            |
            --- medication
            |      |
            |      --- 1234: true
            |      |
            |      --- assf12: true
            |
            --- name: "Rob"

上面的代码也适用于此结构。