FirestoreAdapter无法正常填充回收站视图 [英] FirestoreAdapter not working to populate a Recycler View
问题描述
我是Android的新秀,因此决定将Cloud Firestore用作我的数据库,并使用RecyclerView
填充MainActivity中的列表.我以为在Firestore中使用Firebase-UI
会超级简单,但是我不知道为什么RecyclerView中什么也没装.作为参考,这是Firebase UI页面和这是我基于我的应用程序创建的示例代码.我要做的就是填充用户已保存在数据库中的课程"列表(Course.java如下,因为它只是一个带有名称,日期等的简单POJO,因此未在下面显示).
I'm a rookie with Android and decided to use Cloud Firestore as my db and a RecyclerView
for populating a list in my MainActivity. I thought using Firebase-UI
for Firestore would be super easy, but I can't figure out why nothing is populating in my RecyclerView. For reference, here is the Firebase UI page and here is the example code that I based my app off of. All I'm trying to do is populate a list of "Courses" (Course.java not displayed below since it's just a simple POJO with name, date, etc.) the user has saved in the db.
MainActivity:
MainActivity:
import android.content.Intent;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.PopupMenu;
import android.support.v7.widget.RecyclerView;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.firestore.DocumentSnapshot;
import com.google.firebase.firestore.FirebaseFirestore;
import com.google.firebase.firestore.FirebaseFirestoreException;
import com.google.firebase.firestore.Query;
import com.lorin.deadlineschmedline.R;
import com.lorin.deadlineschmedline.adapters.CourseAdapter;
import butterknife.BindView;
import butterknife.ButterKnife;
public class MainActivity extends AppCompatActivity
implements CourseAdapter.OnCourseSelectedListener,
PopupMenu.OnMenuItemClickListener {
private FirebaseFirestore mFirestore;
private Query mQuery;
private FirebaseUser mCurrentUser;
private RecyclerView.Adapter mAdapter;
private static final String TAG = "MainActivity";
private static final int RC_SIGN_IN = 9001;
private static final int LIMIT = 50;
@BindView(R.id.rv_course_item_list)
RecyclerView mCourseRecyvlerView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ButterKnife.bind(this);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
showPopup(view);
}
});
// Enable Firestore logging
FirebaseFirestore.setLoggingEnabled(true);
// Firestore
mFirestore = FirebaseFirestore.getInstance();
mQuery = mFirestore.collection("courses").whereEqualTo("name", true).limit(LIMIT);
mAdapter = new CourseAdapter(mQuery, this) {
@Override
protected void onDataChanged() {
// Show/hide content if the query returns empty.
if (getItemCount() == 0) {
mCourseRecyvlerView.setVisibility(View.VISIBLE);
//mEmptyView.setVisibility(View.VISIBLE);
} else {
mCourseRecyvlerView.setVisibility(View.VISIBLE);
//mEmptyView.setVisibility(View.GONE);
}
}
@Override
protected void onError(FirebaseFirestoreException e) {
// Show a snackbar on errors
Snackbar.make(findViewById(android.R.id.content),
"Error: check logs for info.", Snackbar.LENGTH_LONG).show();
}
};
mCourseRecyvlerView.setLayoutManager(new LinearLayoutManager(this));
mCourseRecyvlerView.setAdapter(mAdapter);
}
private void showPopup(View v) {
PopupMenu popup = new PopupMenu(this, v);
MenuInflater inflater = popup.getMenuInflater();
inflater.inflate(R.menu.add_component_menu, popup.getMenu());
popup.setOnMenuItemClickListener(this);
popup.show();
}
@Override
public void onStart() {
super.onStart();
mAdapter.startListening();
}
@Override
public void onStop() {
super.onStop();
if (mAdapter != null) {
mAdapter.stopListening();
}
}
@Override
public boolean onMenuItemClick(MenuItem item) {
switch(item.getItemId()) {
case R.id.add_course:
startActivity(new Intent(MainActivity.this, AddCourseActivity.class));
return true;
case R.id.add_course_component:
startActivity(new Intent(MainActivity.this, AddCourseComponentActivity.class));
return true;
default:
return true;
}
}
@Override
public void onCourseSelected(DocumentSnapshot restaurant) {
// Go to the details page for the selected activity
Intent intent = new Intent(this, AddCourseActivity.class);
startActivity(intent);
//overridePendingTransition(R.anim.slide_in_from_right, R.anim.slide_out_to_left);
}
}
我尝试使用调试器逐步遍历MainActivity,但是查询数据库时,我无法从Firestore中获得任何收益(可能是问题).任何想法和反馈将不胜感激!
I've tried stepping through the MainActivity with the debugger, but I can't make heads or tails of what I'm getting back from Firestore when I Query the db (which may be the issue). Any thoughts and feedback would be greatly appreciated!
推荐答案
原来是Firestore查询存在问题.以前,我曾经使用过:
It turned out to be an issue with the Firestore Query. Previously, I had used:
mQuery = mFirestore.collection("courses").whereEqualTo("name", true).limit(LIMIT);
但是,似乎在进行Firestore查询时必须使用orderBy()方法.使用以下方法可以达到目的:
However, it appears that you must use the orderBy() method when making a Firestore Query. Using the following did the trick:
mQuery = mFirestore.collection("courses").orderBy("name").limit(LIMIT);
现在我的数据已按预期显示在RecyclerView中.
Now my data is showing up in the RecyclerView as anticipated.
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