用于maxdistance和MongoDB的单位? [英] Units to use for maxdistance and MongoDB?

问题描述

我正在努力使我了解MongoDB和地理空间搜索. 基本上我想要的是用户能够查询的文档(图像) 是在距用户当前位置一定距离内拍摄的.因此，我要搜索用户在距他站立的位置1公里以内拍摄的所有图像 下面的示例，但我不知道将什么设置为最大距离值.

I am trying to get my head around MongoDB and geospatial searches. Basically what I want is for users to be able to query documents (images) that are shot within a set distance from the users current location. So I the user is searching for all images that are shot within 1 km from where he is standing I try to use the below example but I have no idea what to set as the maxdistance value.

db.places.find({ loc : { $near : [50,50] , $maxDistance : 5 }})

所以我的问题是，如果我要搜索文档，应将maxdistance设置为什么? 半径1公里之内?

So my question is what do I set as maxdistance if I am searching for documents within a 1 km radius?

我完全被困在这里.

推荐答案

为了在km范围内使用mongodb $near查询，您需要将半径值转换为km.默认情况下，mongodb $ near接受$maxDistance作为radius.

In order to use mongodb $near queries with km bounds, you need to convert the radius value to km. By default mongodb $near accepts $maxDistance as radius.

使用km时，将距离转换为111.12(一个度约为111.12公里)，或者保持距离不变.

Convert distance by 111.12 (one degree is approximately 111.12 kilometers) when using km, or leave distance as it is on using degree

对您的问题

如果我要搜索文档中的文档，应将maxdistance设置为什么? 半径1公里?

what do I set as maxdistance if I am searching for documents within a 1 km radius?

您可以使用此

   db.places.find( { loc : { $near : [50,50] , $maxDistance : 1/111.12 } } )

我已经回答了如何在此处使用 mongo地理空间特征详细信息.您可以签出

I have answered how to use mongo geospatial features here in detail. You can check out

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