Firebase 位置查询

问题描述

我正在使用 firebase 在 android 上设计一个基于位置的餐厅搜索应用程序.Firebase 上的餐厅类如下；

I am designing a location based restaurant search application on android with firebase. Restaurant class as follows on firebase;

 restaurants
-key
  address: "NYC"
  city: "New York"
  description: ""
  id: 60000
  latitude: 39.895107
  longitude: 32.797819
  name: "Pizza Store"

片段类

mainActivity.mDatabase.child("restaurants").addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot snapshot) {
            System.out.println("There are " + snapshot.getChildrenCount() + " restaurans");
            for (DataSnapshot postSnapshot : snapshot.getChildren()) {
                Restaurant post = postSnapshot.getValue(Restaurant.class);
                mapmap2.put(post.getName(), postSnapshot.getKey());
                restaurants.add(post);
            }
            adapter = new RestaurantCardViewAdapter(getActivity(), restaurants, MapListFragment.this);
            mRecyclerView.setAdapter(adapter);
        }

        @Override
        public void onCancelled(DatabaseError firebaseError) {
            System.out.println("The read failed: " + firebaseError.getMessage());
        }
    });

现在，我可以列出所有餐厅.但我想查询用户位置.首先，我想列出用户位置附近的 20 家餐馆，当用户加载页面时，我想列出下 20 家最近的餐馆.我在互联网上做一些搜索.我找到了 GeoFire 库，但据我所知，它可以与旧版 firebase 一起使用.如何使用这些条件进行查询?

Right now, I can list all the restaurants. But I want to query on user location. Firstly I want to list 20 restaurants near to user location and when user loads page through I want to get next 20 nearest restaurants. I do some search on internet. I found GeoFire library but as I understand its working with the legacy version of firebase. How can I query with these criterias?

推荐答案

Firebase 查询只能按单个属性过滤/排序.由于位置由经度和纬度组成，因此按照您现在的格式，您无法根据位置进行查询.

Firebase Queries can only filter/order by a single property. Since a location consists of longitude and latitude, in the format you have right now, you cannot query based on location.

幸运的是，有一个名为 GeoFire 的附加库.这个库将经度和纬度组合成一个名为 geohash 的属性.基于此属性，它可以按到给定位置的距离进行过滤.

Luckily there is an add-on library called GeoFire. This library combines the longitude and latitude into a single property called a geohash. Based on this property it can filter by distance to a given location.

我建议您查看 Geofire，看看它是否适合您的用例.

I recommend you check out Geofire and see if it fits your use-case.

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