Search Geospatially地理空间搜索¶

Coordinates on an Earth-like Sphere类地球球体上的坐标¶

For geospatial queries using longitude and latitude coordinates on an Earth-like sphere, use the GeoJSON query format. 对于使用类地球球体上的经度和纬度坐标的地理空间查询，请使用GeoJSON查询格式。While GeoJSON has multiple types, all GeoJSON data types use some form of the following structure:虽然GeoJSON有多种类型，但所有GeoJSON数据类型都使用以下某种形式的结构：

<field> : {
   type: <GeoJSONtype>,
coordinates: [
[longitude_1, latitude_1],
...
[longitude_n, latitude_n]
]
}

The object type determines the number of coordinates. 对象类型确定坐标数。For instance, a Point requires only one coordinate: a longitude and a latitude. 例如，一个Point只需要一个坐标：经度和纬度。A Line uses two coordinates: a longitude and a latitude for each end. Line使用两个坐标：每一端的经度和纬度。A Polygon consists of a list of coordinates in which the first and last coordinate are the same, effectively closing the polygon. Polygon由第一个和最后一个坐标相同的坐标列表组成，有效地闭合多边形。To learn more about the GeoJSON shapes you can use in MongoDB, consult the GeoJSON manual entry.要了解有关可以在MongoDB中使用的GeoJSON形状的更多信息，请参阅GeoJSON手册条目。

To enable querying GeoJSON data, you must add the field to a 2dsphere index. 要启用查询GeoJSON数据，必须将该字段添加到2dsphere索引中。The following snippet creates an index on the location.geo field in the theaters collection using the createIndex() method:以下代码段使用createIndex()方法在theaters集合的location.geo字段上创建索引：

db.theaters.createIndex({location.geo: "2dsphere"})

Coordinates on a 2D Plane二维平面上的坐标¶

You can also express geospatial queries using x and y coordinates in a two-dimentional Euclidian plane. 还可以使用二维欧几里得平面中的x和y坐标表示地理空间查询。Until MongoDB, this was the only format compatible with geospatial queries, and are now referred to as "legacy coordinate pairs".在MongoDB之前，这是唯一与地理空间查询兼容的格式，现在被称为“传统坐标对”。

Legacy coordinate pairs use the following structure:传统坐标对使用以下结构：

<field> : [ x, y ]

The field should contain an array of two values in which the first represents the x axis value and the second represents the y axis value.该字段应包含两个值的数组，其中第一个值表示x轴值，第二个值表示y轴值。

To enable querying using legacy coordinate pairs, create a 2d index on the field on the collection. 要启用使用旧坐标对的查询，请在集合上的字段上创建2d索引。The following snippet creates an index on the coordinates field in the shipwrecks collection using the createIndex() method:以下代码段使用createIndex()方法在shipwrecks集合的coordinates字段上创建索引：

db.shipwrecks({coordinates: "2d"})

See the MongoDB server manual page on legacy coordinate pairs for more information.有关更多信息，请参阅关于传统坐标对的MongoDB服务器手册页面。

Query by Proximity¶

The $near operator accepts a set of longitude-latitude coordinates and returns documents ordered from nearest to farthest. $near运算符接受一组经纬度坐标，并返回从最近到最远排序的文档。To limit the results to a maximum distance in meters, use the $maxDistance option. 要将结果限制为以米为单位的最大距离，请使用$maxDistance选项。For a complete list of options, see the reference documentation for $near. 有关选项的完整列表，请参阅$near的参考文档。The following example queries for theaters within 10,000 meters of [ -73.9667, 40.78 ].以下示例查询离[ -73.9667, 40.78 ]10000米范围内的影院。

  const query = {
    "location.geo": {
      $near: {
        $geometry: { type: "Point", coordinates: [-73.9667, 40.78] },
        $maxDistance: 10000,
      },
    },
  };

  // find documents based on our query
  const cursor = theaters.find(query);

Query Within a Range范围内的查询¶

The $geoWithin operator selects documents with geospatial data that exist within a specified shape. $geoWithin操作符用于选择包含存在于指定形状中的地理空间数据的文档。The following example searches for movie theaters in the New England area:以下示例搜索新英格兰地区的电影院：

  const query = {
    "location.geo": {
      $geoWithin: {
        $geometry: {
          type: "Polygon",
          coordinates: [
            [
              [-72, 40],
              [-74, 41],
              [-72, 39],
              [-72, 40],
            ],
          ],
        },
      },
    },
  };

  // find documents based on our query
  const cursor = theaters.find(query);

See the MongoDB server manual page on geospatial query operators for more information on the operators you can use in your query.有关可在查询中使用的运算符的更多信息，请参阅MongoDB服务器手册中有关地理空间查询运算符的页面。