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- $geoWithin
$geoWithin¶
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Definition¶
- $geoWithin¶
New in version 2.4: $geoWithin replaces $within which is deprecated.
Selects documents with geospatial data that exists entirely within a specified shape. When determining inclusion, MongoDB considers the border of a shape to be part of the shape, subject to the precision of floating point numbers.
The specified shape can be either a GeoJSON Polygon (either single-ringed or multi-ringed), a GeoJSON MultiPolygon, or a shape defined by legacy coordinate pairs. The $geoWithin operator uses the $geometry operator to specify the GeoJSON object.
To specify a GeoJSON polygons or multipolygons using the default coordinate reference system (CRS), use the following syntax:
{ <location field>: { $geoWithin: { $geometry: { type: <"Polygon" or "MultiPolygon"> , coordinates: [ <coordinates> ] } } } }
For $geoWithin queries that specify GeoJSON geometries with areas greater than a single hemisphere, the use of the default CRS results in queries for the complementary geometries.
New in version 3.0: To specify a single-ringed GeoJSON polygon with a custom MongoDB CRS, use the following prototype that specifies the custom MongoDB CRS in the $geometry expression:
{ <location field>: { $geoWithin: { $geometry: { type: "Polygon" , coordinates: [ <coordinates> ], crs: { type: "name", properties: { name: "urn:x-mongodb:crs:strictwinding:EPSG:4326" } } } } } }
The custom MongoDB CRS uses a counter-clockwise winding order and allows $geoWithin to support queries with a single-ringed GeoJSON polygon whose area is greater than or equal to a single hemisphere. If the specified polygon is smaller than a single hemisphere, the behavior of $geoWithin with the MongoDB CRS is the same as with the default CRS. See also “Big” Polygons.
If querying for inclusion in a shape defined by legacy coordinate pairs on a plane, use the following syntax:
{ <location field>: { $geoWithin: { <shape operator>: <coordinates> } } }
The available shape operators are:
- $box,
- $polygon,
- $center (defines a circle), and
- $centerSphere (defines a circle on a sphere).
Important
If you use longitude and latitude, specify coordinates in order of longitude, latitude.
Behavior¶
Geospatial Indexes¶
$geoWithin does not require a geospatial index. However, a geospatial index will improve query performance. Both 2dsphere and 2d geospatial indexes support $geoWithin.
Unsorted Results¶
The $geoWithin operator does not return sorted results. As such, MongoDB can return $geoWithin queries more quickly than geospatial $near or $nearSphere queries, which sort results.
“Big” Polygons¶
For $geoWithin, if you specify a single-ringed polygon that has an area greater than a single hemisphere, include the custom MongoDB coordinate reference system in the $geometry expression; otherwise, $geoWithin queries for the complementary geometry. For all other GeoJSON polygons with areas greater than a hemisphere, $geoWithin queries for the complementary geometry.
Examples¶
Within a Polygon¶
The following example selects all loc data that exist entirely within a GeoJSON Polygon. The area of the polygon is less than the area of a single hemisphere:
db.places.find(
{
loc: {
$geoWithin: {
$geometry: {
type : "Polygon" ,
coordinates: [ [ [ 0, 0 ], [ 3, 6 ], [ 6, 1 ], [ 0, 0 ] ] ]
}
}
}
}
)
For single-ringed polygons with areas greater than a single hemisphere, see Within a “Big” Polygon.
Within a “Big” Polygon¶
To query with a single-ringed GeoJSON polygon whose area is greater than a single hemisphere, the $geometry expression must specify the custom MongoDB coordinate reference system. For example:
db.places.find(
{
loc: {
$geoWithin: {
$geometry: {
type : "Polygon" ,
coordinates: [
[
[ -100, 60 ], [ -100, 0 ], [ -100, -60 ], [ 100, -60 ], [ 100, 60 ], [ -100, 60 ]
]
],
crs: {
type: "name",
properties: { name: "urn:x-mongodb:crs:strictwinding:EPSG:4326" }
}
}
}
}
}
)
- $within¶
Deprecated since version 2.4: $geoWithin replaces $within in MongoDB 2.4.
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