我的应用程序允许Users创建Charts，其存储在数据库中的FireStore这样的：
charts
> documentKey1
> description = "Example description"
> name = "Chart name 1"
> uId = user1Id_string
> documentKey2
> description = "Another example description"
> name = "Chart name 2"
> uId = user2Id_string
> documentKey3
> description = "Example description again"
> name = "Chart name 3"
> uId = user1Id_string
每个用户可以拥有多个图表。目前，我的MainActivity检索所有当前用户的图表从数据库中，他们分类成一个给定的顺序（由用户设定），并将其显示在一个片段中的FirebaseRecyclerView。
在MainActivity在一个ViewPager 2个片段。有关的一个FragmentMyCharts其中包含：
public class FragmentMyCharts extends FragmentChartsList {
public FragmentMyCharts() {}
public Query getQuery(FirebaseFirestore databaseReference,
String orderBy,
Query.Direction direction) {
// Specify the query which is used to retrieve this user's charts
return databaseReference.collection("charts")
.whereEqualTo("uid", getUid())
.orderBy(orderBy, direction);
}
}
这延长FragmentChartsList，其如下所示：
public abstract class FragmentChartsList extends Fragment {
private FirebaseFirestore mDatabaseRef;
private ChartListAdapter mAdapter;
private RecyclerView mRecycler;
private String mOrder = "name", mFilter;
private Query.Direction mDirection = Query.Direction.DESCENDING;
private TextView mLoadingList, mEmptyList;
public FragmentChartsList() {}
@Override
public View onCreateView(@NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
super.onCreateView(inflater, container, savedInstanceState);
// Inflate layout, and find Recycler View which will hold the list
View rootView = inflater.inflate(
R.layout.fragment_charts_list, container, false);
mRecycler = rootView.findViewById(R.id.charts_list);
mRecycler.setHasFixedSize(true);
mLoadingList = rootView.findViewById(R.id.loading_list);
mEmptyList = rootView.findViewById(R.id.empty_list);
// Set up Layout Manager, and set Recycler View to use it
LinearLayoutManager mManager = new LinearLayoutManager(getActivity());
mManager.setReverseLayout(true);
mManager.setStackFromEnd(true);
mRecycler.setLayoutManager(mManager);
// Connect to the database
mDatabaseRef = FirebaseFirestore.getInstance();
setOrderAndFilter(mOrder, mDirection, mFilter);
return rootView;
}
public abstract Query getQuery(FirebaseFirestore databaseReference,
String orderBy,
Query.Direction direction);
public void setOrderAndFilter(String order, Query.Direction direction, String filterString) {
mOrder = order;
mDirection = direction;
mFilter = filterString;
Query mChartsQuery = getQuery(mDatabaseRef, mOrder, mDirection);
// Update recycler options
FirestoreRecyclerOptions<Chart> recyclerOptions = new FirestoreRecyclerOptions.Builder<Chart>()
.setQuery(mChartsQuery, Chart.class)
.build();
mAdapter = new ChartListAdapter(recyclerOptions, getActivity());
mAdapter.startListening();
mRecycler.setAdapter(mAdapter);
mChartsQuery.addSnapshotListener(new EventListener<QuerySnapshot>() {
@Override
public void onEvent(@Nullable QuerySnapshot queryDocumentSnapshots, @Nullable FirebaseFirestoreException e) {
if (queryDocumentSnapshots != null) {
// Hide "loading lists" text
mLoadingList.setVisibility(View.GONE);
if(queryDocumentSnapshots.size() > 0) {
mEmptyList.setVisibility(View.GONE);
mRecycler.setVisibility(View.VISIBLE);
}else {
// If number of Charts = 0,
// if we have filtered, show "no results"
// otherwise, show "no charts"
mEmptyList.setVisibility(View.VISIBLE);
mRecycler.setVisibility(View.GONE);
}
}
}
});
}
这涉及到ChartListAdapter类，它是这样定义的：
public class ChartListAdapter extends FirestoreRecyclerAdapter<Chart, ChartViewHolder> {
private Activity mActivity;
public ChartListAdapter(FirestoreRecyclerOptions<Chart> recyclerOptions, Activity activity) {
super(recyclerOptions);
mActivity = activity;
}
@Override
protected void onBindViewHolder(@NonNull ChartViewHolder holder, int position, @NonNull Chart model) {
final String chartKey = this.getSnapshots().getSnapshot(position).getId();
model.setKey(chartKey);
// Set click listener for the chart
// On click, the user can view the chart
holder.itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(mActivity, ActivityViewChart.class);
intent.putExtra("ChartKey", chartKey);
mActivity.startActivity(intent);
}
});
// Implement long-click menu
mActivity.registerForContextMenu(holder.itemView);
// Bind Chart to ViewHolder
holder.bindToChart(model);
}
@NonNull
@Override
public ChartViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.item_chart, parent, false);
return new ChartViewHolder(view);
}
}
所以，目前这个检索所有当前用户的图表和排序并显示它们。我希望能够做的是筛选结果，这样用户可以输入一些搜索文本，只有图表，其名称或描述包含文本显示。
我的理解是，我不能这样做，因为该公司的FireStore查询的一部分，所以我的想法是，以检索图表的完整列表，然后遍历所有这些，删除任何不符合标准，再展其余的（也有不太可能在数百名单图表，大多数用户将有大约10）。
我无法弄清楚如何做到这一点，我甚至不能确定它是否是最好的方式。最明显的地方做这似乎是当我snapshotListener添加到ChartsQuery的FragmentChartsList，但我不能找到一种方法，从列表中删除一个单独的快照。或者，我可以把所有的物品放入recyclerView然后删除我不想要的人？
任何人都可以点我在正确的方向？我发现一切都在网上似乎是有关删除recyclerView项目，并从数据库中，这是我不想做删除。
您可以使用搜索过滤器功能下面的查询。
databaseReference.collection("charts")
.whereEqualTo("uid", getUid())
.orderBy("name")
.startAt(searchText)
.endAt(searchtText + "\uf8ff");
通过搜索文本，以startAt（）和ENDAT（）函数，并将其命名为您documentField。
并通过此查询到firestoreAdapter它会为你提供的结果记录。