android - 根据来自 Firebase 的优先级对数据进行排序并将其显示在 FirebaseRecyclerAdapter 中

Question

我有来自实时数据库的数据，它被绑定(bind)到 FirebaseRecyclerAdapter 截至目前，数据正在按照数据插入实时数据库时的排序方式获取，但是在我按类别排序或搜索后，订单变得分散。

我添加了一个名为 priority 的字段，我想从中分配要显示的第一个项目等等。我该怎么做，我需要控制用户看到项目的顺序。

这是实时数据库及其所有字段的图像。我希望它由 child 订购 - 优先。

我还添加了下面的代码，我用它绑定(bind)到 FirebaseRecyclerAdapter

package com.test.testbv;

import android.content.Intent;
import android.os.Bundle;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.view.MenuItemCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBar;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.SearchView;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;

import com.firebase.ui.database.FirebaseRecyclerAdapter;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.Query;


public class MainActivity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener {

    RecyclerView mRecyclerView;
    FirebaseDatabase mFirebaseDatabase;
    DatabaseReference mRef;

    private FirebaseAuth mAuth;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FirebaseAuth.getInstance().getCurrentUser();

        if (FirebaseAuth.getInstance().getCurrentUser() != null) {
            // User is signed in.
        } else {
            // No user is signed in.
            redirectToLogin();
        }

        // Action Bar

        ActionBar actionBar = getSupportActionBar();
        actionBar.setTitle("Coupons List");

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

        // Set Layout
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));

        // Send Query to Firebase Db
        mFirebaseDatabase = FirebaseDatabase.getInstance();
        mRef = mFirebaseDatabase.getReference("Data");

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.addDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);
    }


    @Override
    protected void onStart() {
        super.onStart();
        FirebaseRecyclerAdapter<Model, ViewHolder> firebaseRecyclerAdapter =
                new FirebaseRecyclerAdapter<Model, ViewHolder>(
                        Model.class,
                        R.layout.row,
                        ViewHolder.class,
                        mRef
                ) {
                    @Override
                    protected void populateViewHolder(ViewHolder viewHolder, Model model, int position) {
                        viewHolder.setDetails(getApplicationContext(), model.getTitle(), model.getDescription(), model.getImage());
                    }

                    @Override
                    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
                        ViewHolder viewHolder = super.onCreateViewHolder(parent, viewType);

                        viewHolder.setOnClickListener(new ViewHolder.clickListener() {

                            @Override
                            public void onItemClick(View view, int position) {
                                // get Data from firebase at the position clicked
                                String mTitle = getItem(position).getTitle();
                                String mDesc = getItem(position).getDescription();
                                String mImage = getItem(position).getImage();

                                // Pass this data to new activity
                                Intent intent = new Intent(view.getContext(), PostDetailActivity.class);

                                intent.putExtra("image", mImage);
                                intent.putExtra("title", mTitle);
                                intent.putExtra("description", mDesc);
                                startActivity(intent);

                            }

                            @Override
                            public void onItemLongClick(View view, int position) {

                            }

                        });

                        return viewHolder;
                    }
                };
        // Set adapter to recycler view
        mRecyclerView.setAdapter(firebaseRecyclerAdapter);
    }
}

Answer 1

要解决这个问题，您应该使用如下所示的查询:

mFirebaseDatabase = FirebaseDatabase.getInstance();
mRef = mFirebaseDatabase.getReference("Data");
Query mQuery = mRef.orderByChild("prority");

如果您想查询特定的优先级，比如说优先级 1，请使用以下查询:

Query mQuery = mRef.orderByChild("prority").equalsTo(1);