Geographic Database FunctionsLink to this heading#

AreaLink to this heading#

class Area(expression, **extra)Link to this definition#

Availability: MySQL, Oracle, PostGIS, SpatiaLite

Accepts a single geographic field or expression and returns the area of the field as an Area measure. On MySQL, a raw float value is returned, as it's not possible to automatically determine the unit of the field.

AsGeoJSONLink to this heading#

class AsGeoJSON(expression, bbox=False, crs=False, precision=8, **extra)Link to this definition#

Availability: PostGIS, SpatiaLite (≥ 3.0)

Accepts a single geographic field or expression and returns a GeoJSON representation of the geometry. Note that the result is not a complete GeoJSON structure but only the geometry key content of a GeoJSON structure. See also GeoJSON Serializer.

Example:

>>> City.objects.annotate(json=AsGeoJSON('point')).get(name='Chicago').json
{"type":"Point","coordinates":[-87.65018,41.85039]}

AsGMLLink to this heading#

class AsGML(expression, version=2, precision=8, **extra)Link to this definition#

Availability: PostGIS, SpatiaLite (≥ 2.4.0-RC4)

Accepts a single geographic field or expression and returns a Geographic Markup Language (GML) representation of the geometry.

Example:

>>> qs = Zipcode.objects.annotate(gml=AsGML('poly'))
>>> print(qs[0].gml)
<gml:Polygon srsName="EPSG:4326"><gml:OuterBoundaryIs>-147.78711,70.245363 ...
-147.78711,70.245363</gml:OuterBoundaryIs></gml:Polygon>

AsKMLLink to this heading#

class AsKML(expression, precision=8, **extra)Link to this definition#

Availability: PostGIS, SpatiaLite (≥ 2.4.0-RC4)

Accepts a single geographic field or expression and returns a Keyhole Markup Language (KML) representation of the geometry.

Example:

>>> qs = Zipcode.objects.annotate(kml=AsKML('poly'))
>>> print(qs[0].kml)
<Polygon><outerBoundaryIs><LinearRing><coordinates>-103.04135,36.217596,0 ...
-103.04135,36.217596,0</coordinates></LinearRing></outerBoundaryIs></Polygon>

AsSVGLink to this heading#

class AsSVG(expression, relative=False, precision=8, **extra)Link to this definition#

Availability: PostGIS, SpatiaLite

Accepts a single geographic field or expression and returns a Scalable Vector Graphics (SVG) representation of the geometry.

BoundingCircleLink to this heading#

class BoundingCircle(expression, num_seg=48, **extra)Link to this definition#

Availability: PostGIS

Accepts a single geographic field or expression and returns the smallest circle polygon that can fully contain the geometry.

CentroidLink to this heading#

class Centroid(expression, **extra)Link to this definition#

Availability: MySQL, PostGIS, Oracle, SpatiaLite

Accepts a single geographic field or expression and returns the centroid value of the geometry.

DifferenceLink to this heading#

class Difference(expr1, expr2, **extra)Link to this definition#

Availability: PostGIS, Oracle, SpatiaLite

Accepts two geographic fields or expressions and returns the geometric difference, that is the part of geometry A that does not intersect with geometry B.

DistanceLink to this heading#

class Distance(expr1, expr2, spheroid=None, **extra)Link to this definition#

Availability: MySQL (≥ 5.6.1), PostGIS, Oracle, SpatiaLite

Accepts two geographic fields or expressions and returns the distance between them, as a Distance object. On MySQL, a raw float value is returned, as it's not possible to automatically determine the unit of the field.

On backends that support distance calculation on geodetic coordinates, the proper backend function is automatically chosen depending on the SRID value of the geometries (e.g. ST_Distance_Sphere on PostGIS).

When distances are calculated with geodetic (angular) coordinates, as is the case with the default WGS84 (4326) SRID, you can set the spheroid keyword argument to decide if the calculation should be based on a simple sphere (less accurate, less resource-intensive) or on a spheroid (more accurate, more resource-intensive).

In the following example, the distance from the city of Hobart to every other PointField in the AustraliaCity queryset is calculated:

>>> from django.contrib.gis.db.models.functions import Distance
>>> pnt = AustraliaCity.objects.get(name='Hobart').point
>>> for city in AustraliaCity.objects.annotate(distance=Distance('point', pnt)):
...     print(city.name, city.distance)
Wollongong 990071.220408 m
Shellharbour 972804.613941 m
Thirroul 1002334.36351 m
...

EnvelopeLink to this heading#

class Envelope(expression, **extra)Link to this definition#

Availability: MySQL, PostGIS, SpatiaLite

Accepts a single geographic field or expression and returns the geometry representing the bounding box of the geometry.

ForceRHRLink to this heading#

class ForceRHR(expression, **extra)Link to this definition#

Availability: PostGIS

Accepts a single geographic field or expression and returns a modified version of the polygon/multipolygon in which all of the vertices follow the right-hand rule.

GeoHashLink to this heading#

class GeoHash(expression, **extra)Link to this definition#

Availability: PostGIS

Accepts a single geographic field or expression and returns a GeoHash representation of the geometry.

IntersectionLink to this heading#

class Intersection(expr1, expr2, **extra)Link to this definition#

Availability: PostGIS, Oracle, SpatiaLite

Accepts two geographic fields or expressions and returns the geometric intersection between them.

LengthLink to this heading#

class Length(expression, spheroid=True, **extra)Link to this definition#

Availability: MySQL, Oracle, PostGIS, SpatiaLite

Accepts a single geographic linestring or multilinestring field or expression and returns its length as an Distance measure. On MySQL, a raw float value is returned, as it's not possible to automatically determine the unit of the field.

On PostGIS and SpatiaLite, when the coordinates are geodetic (angular), you can specify if the calculation should be based on a simple sphere (less accurate, less resource-intensive) or on a spheroid (more accurate, more resource-intensive) with the spheroid keyword argument.

MemSizeLink to this heading#

class MemSize(expression, **extra)Link to this definition#

Availability: PostGIS

Accepts a single geographic field or expression and returns the memory size (number of bytes) that the geometry field takes.

NumGeometriesLink to this heading#

class NumGeometries(expression, **extra)Link to this definition#

Availability: MySQL, PostGIS, Oracle, SpatiaLite

Accepts a single geographic field or expression and returns the number of geometries if the geometry field is a collection (e.g., a GEOMETRYCOLLECTION or MULTI* field); otherwise returns None.

NumPointsLink to this heading#

class NumPoints(expression, **extra)Link to this definition#

Availability: MySQL, PostGIS, Oracle, SpatiaLite

Accepts a single geographic field or expression and returns the number of points in the first linestring in the geometry field; otherwise returns None.

PerimeterLink to this heading#

class Perimeter(expression, **extra)Link to this definition#

Availability: PostGIS, Oracle, SpatiaLite (≥ 4.0)

Accepts a single geographic field or expression and returns the perimeter of the geometry field as a Distance object. On MySQL, a raw float value is returned, as it's not possible to automatically determine the unit of the field.

PointOnSurfaceLink to this heading#

class PointOnSurface(expression, **extra)Link to this definition#

Availability: PostGIS, Oracle, SpatiaLite

Accepts a single geographic field or expression and returns a Point geometry guaranteed to lie on the surface of the field; otherwise returns None.

ReverseLink to this heading#

class Reverse(expression, **extra)Link to this definition#

Availability: PostGIS, Oracle, SpatiaLite (≥ 4.0)

Accepts a single geographic field or expression and returns a geometry with reversed coordinates.

ScaleLink to this heading#

class Scale(expression, x, y, z=0.0, **extra)Link to this definition#

Availability: PostGIS, SpatiaLite

Accepts a single geographic field or expression and returns a geometry with scaled coordinates by multiplying them with the x, y, and optionally z parameters.

SnapToGridLink to this heading#

class SnapToGrid(expression, *args, **extra)Link to this definition#

Availability: PostGIS, SpatiaLite (≥ 3.1)

Accepts a single geographic field or expression and returns a geometry with all points snapped to the given grid. How the geometry is snapped to the grid depends on how many numeric (either float, integer, or long) arguments are given.

SymDifferenceLink to this heading#

class SymDifference(expr1, expr2, **extra)Link to this definition#

Availability: PostGIS, Oracle, SpatiaLite

Accepts two geographic fields or expressions and returns the geometric symmetric difference (union without the intersection) between the given parameters.

TransformLink to this heading#

class Transform(expression, srid, **extra)Link to this definition#

Availability: PostGIS, Oracle, SpatiaLite

Accepts a geographic field or expression and a SRID integer code, and returns the transformed geometry to the spatial reference system specified by the srid parameter.

TranslateLink to this heading#

class Translate(expression, x, y, z=0.0, **extra)Link to this definition#

Availability: PostGIS, SpatiaLite

Accepts a single geographic field or expression and returns a geometry with its coordinates offset by the x, y, and optionally z numeric parameters.

UnionLink to this heading#

class Union(expr1, expr2, **extra)Link to this definition#

Availability: MySQL (≥ 5.6.1), PostGIS, Oracle, SpatiaLite

Accepts two geographic fields or expressions and returns the union of both geometries.