$polygon¶

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Definition
Behavior
Example

Definition¶

$polygon¶

1.9 新版功能.

Specifies a polygon for a geospatial $geoWithin query on legacy coordinate pairs. The query returns pairs that are within the bounds of the polygon. The operator does not query for GeoJSON objects.

To define the polygon, specify an array of coordinate points:

{
   <location field>: {
      $geoWithin: {
         $polygon: [ [ <x1> , <y1> ], [ <x2> , <y2> ], [ <x3> , <y3> ], ... ]
      }
   }
}

The last point is always implicitly connected to the first. You can specify as many points, i.e. sides, as you like.

重要

If you use longitude and latitude, specify longitude first.

Behavior¶

The $polygon operator calculates distances using flat (planar) geometry.

Applications can use $polygon without having a geospatial index. However, geospatial indexes support much faster queries than the unindexed equivalents.

Only the 2d geospatial index supports the $polygon operator.

Example¶

The following query returns all documents that have coordinates that exist within the polygon defined by [ 0 , 0 ], [ 3 , 6 ], and [ 6 , 0 ]:

db.places.find(
  {
     loc: {
       $geoWithin: { $polygon: [ [ 0 , 0 ], [ 3 , 6 ], [ 6 , 0 ] ] }
     }
  }
)

← $box $uniqueDocs →