如何在Firebase Android中执行SQL IN子句查询
如何在Firebase Android中查询SQL IN子句?我想在Firebase
Recycler适配器中使用它,以便根据某些条件仅检索某些子级。类似于以下语句:
SQL----> select * from posts where city in(10 cities comes here)
我需要一个Firebase查询才能在Firebase Recycler适配器中使用它。
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我找到了解决方案:我们无法使用
FirebaseRecyclerAdapter
。相反,我们必须创建可扩展的自定义适配器RecyclerView.ViewHolder
。要将值传递给此适配器,首先我们必须使用检索数据
addValueEventListener
,然后必须将值传递给我们的适配器。这是我的代码…
final ArrayList<Timeline> timelines = new ArrayList<>(); mDatabaseTimeline.addChildEventListener(new ChildEventListener() { @Override public void onChildAdded(DataSnapshot dataSnapshot, String s) { final Timeline timeline = dataSnapshot.getValue(Timeline.class); if(timeline != null){ mDatabaseFriends.child(mAuth.getCurrentUser().getUid()).child("active").addListenerForSingleValueEvent(new ValueEventListener() { @Override public void onDataChange(DataSnapshot dataSnapshot) { if (mAuth.getCurrentUser().getUid().equals(timeline.getUid()) || dataSnapshot.hasChild(timeline.getUid())) { timelines.add(timeline); mTimelineRecycler.setAdapter(new RecyclerAdapter(TimelineFragment.this.getContext(), timelines)); } } @Override public void onCancelled(DatabaseError databaseError) { } }); } } @Override public void onChildChanged(DataSnapshot dataSnapshot, String s) { } @Override public void onChildRemoved(DataSnapshot dataSnapshot) { } @Override public void onChildMoved(DataSnapshot dataSnapshot, String s) { } @Override public void onCancelled(DatabaseError databaseError) { } });
适配器----->
public class RecyclerAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> { Context context; ArrayList<Timeline> timeline; public RecyclerAdapter(Context context, ArrayList<Timeline> timeline) { this.context = context; this.timeline = timeline; } @Override public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { LayoutInflater inflater = LayoutInflater.from(context); View row = inflater.inflate(R.layout.timeline_row, parent, false); TimelineViewHolder holder = new TimelineViewHolder(row); return holder; } @Override public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) { final String post_key = timeline.get(position).getPostkey(); ((TimelineViewHolder) holder).setUsername(timeline.get(position).getUsername()); } @Override public int getItemCount() { return timeline.size(); } public class TimelineViewHolder extends RecyclerView.ViewHolder { public TimelineViewHolder(View itemView) { super(itemView); view = itemView; } public View getView() { return view; } public void setUsername(String username) { TextView usernameTxtView = (TextView) view.findViewById(R.id.timeline_username); usernameTxtView.setText(username); } } }