筛选结果在FirebaseRecyclerAdapter中 [英] Filter results in FirebaseRecyclerAdapter

问题描述

我是Android新手，刚刚开始了解一些概念，比如 RecyclerView 。我正在使用Firebase作为数据库，所以我为此实施了Firebase解决方案。

我的适配器：

  FirebaseRecyclerAdapter< Offer，OfferViewHolder> adapter = new FirebaseRecyclerAdapter< Offer，OfferViewHolder>（
 Offer.class，
 R.layout.card_item，
 OfferViewHolder.class，
 mDatabaseReference.child（offer）。getRef （）
）{
 @Override 
 protected void populateViewHolder（OfferViewHolder viewHolder，Offer model，int position）{
 if（tvNoMovies.getVisibility（）== View.VISIBLE）{ 
 tvNoMovies.setVisibility（View.GONE）; 
} 
 
 viewHolder.tvHeading.setText（model.getHeader（））; 
 viewHolder.tvStoreName.setText（model.getStoreName（））; 
 
} 
}; 
  

现在我有两个问题：

1. 是否可以过滤适配器内部的结果，还是必须使用 ChildEventListeners 引用包含数组或对象本身的键时如何检索子值？

解决方案您可以初始化 FirebaseRecyclerAdapter 与 DatabaseReference 或者 Query 。顾名思义，后者允许您在数据库中的特定位置获取子集的一部分。

例如，如果您只想显示一个特定的商店：

$ p $ DatabaseReference offers = mDatabaseReference.child（offer）。getRef（）;
查询storeOffers = offers.orderByChild（storeName）。equalTo（A。lazzi's store）;
FirebaseRecyclerAdapter< Offer，OfferViewHolder> （
Offer.class，
R.layout.card_item，
OfferViewHolder.class，
storeOffers
）{


I am new to Android and just started to understand some concepts like the RecyclerView. I am using Firebase as a database so I implemented the Firebase solution for that.

My Adapter:

FirebaseRecyclerAdapter<Offer,OfferViewHolder> adapter = new FirebaseRecyclerAdapter<Offer, OfferViewHolder>(
            Offer.class,
            R.layout.card_item,
            OfferViewHolder.class,
            mDatabaseReference.child("offer").getRef()
    ) {
        @Override
        protected void populateViewHolder(OfferViewHolder viewHolder, Offer model, int position) {
            if(tvNoMovies.getVisibility()== View.VISIBLE){
                tvNoMovies.setVisibility(View.GONE);
            }

            viewHolder.tvHeading.setText(model.getHeader());
            viewHolder.tvStoreName.setText(model.getStoreName());

        }
    };

Now I have two questions:

1. Is it possible to filter results inside the adapter or do i have to use ChildEventListeners for that?
2. When referencing to a key that contains an Array or an object itself how to retrieve child values?

解决方案

You can initialize the FirebaseRecyclerAdapter with either a DatabaseReference or a Query. As its name implies, the latter allows you to get a subset of the children at a specific location in the database.

For example say if you want to only show offers from a specific store:

DatabaseReference offers = mDatabaseReference.child("offer").getRef();
Query storeOffers = offers.orderByChild("storeName").equalTo("A. lazzi's store");
FirebaseRecyclerAdapter<Offer,OfferViewHolder> adapter = new FirebaseRecyclerAdapter<Offer, OfferViewHolder>(
        Offer.class,
        R.layout.card_item,
        OfferViewHolder.class,
        storeOffers
) {

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