如何使用GeoQuery对位置和特定值进行排序? (安卓) [英] How can I use a GeoQuery to sort by both location and certain value? (Android)
问题描述
这是Firestore的地理查询: https://github.com/imperiumlabs/GeoFirestore-Android 但这不允许进一步排序. 我想按最近和最著名的用户进行排序，我该怎么做?还有其他可能的库吗?
This is a Geoquery for Firestore: https://github.com/imperiumlabs/GeoFirestore-Android But it doesn't allow for further sorting. I want to sort by the nearest and most famous users, how could i do such a thing? Are there any other possible libraries?
推荐答案
Geofire在Firestore上似乎无法完成某些工作:它对两个值(纬度和经度)执行范围查询.它通过创建一个geohash值来做到这一点，该值将纬度和经度合并为一个值，该值可用于选择彼此接近的文档范围.
Geofire already does something seemingly impossible on Firestore: it performs a range query on two values (lat and lon). It does this by creating a geohash value, which combines the latitude and longitude into a single value, that can be used to select a range of documents that are close to each other.
要允许在另一个字段的范围内进行附加选择，您必须找到一种将另一个字段的值合并到Geohash值中的方法.从本质上讲，这意味着您必须找到一种方法来表达名声(您的其他属性)作为位置(距离)的函数的重要性，并以此为基础计算单个字段值.尽管从技术上讲这可能可行，但我怀疑有人能做到这一点.
To allow additionally select on the range of another field, you'd have to find a way to combine the value of that other field into the Geohash value. It essentially means you have to find a way to express the importance of fame (your additional property) as a function of location (the distance), and compute a single field value based on that. While this may technically possible, I doubt anyone has every done it.
要了解位置过滤的工作原理(以及为什么添加一个额外的字段并不像看起来那样简单)，请看一下:
To learn how filtering on location works (and why adding an extra field is not as simple as it may seem), have a look at:
- the video of my talk on geofiltering on Firestore
- Jeff's much more concise Realtime GeoQueries With Firestore video and article
- Firebase/GeoFire - Most popular item at location
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