from django.contrib.gis import forms
from django.contrib.gis.db.models.lookups import gis_lookups
from django.contrib.gis.db.models.proxy import SpatialProxy
from django.contrib.gis.gdal import HAS_GDAL
from django.contrib.gis.geometry.backend import Geometry, GeometryException
from django.core.exceptions import ImproperlyConfigured
from django.db.models.expressions import Expression
from django.db.models.fields import Field
from django.utils import six
from django.utils.translation import ugettext_lazy as _
# Local cache of the spatial_ref_sys table, which holds SRID data for each
# spatial database alias. This cache exists so that the database isn't queried
# for SRID info each time a distance query is constructed.
_srid_cache = {}
def get_srid_info(srid, connection):
"""
Returns the units, unit name, and spheroid WKT associated with the
given SRID from the `spatial_ref_sys` (or equivalent) spatial database
table for the given database connection. These results are cached.
"""
global _srid_cache
try:
# The SpatialRefSys model for the spatial backend.
SpatialRefSys = connection.ops.spatial_ref_sys()
except NotImplementedError:
# No `spatial_ref_sys` table in spatial backend (e.g., MySQL).
return None, None, None
if connection.alias not in _srid_cache:
# Initialize SRID dictionary for database if it doesn't exist.
params = [connection.ops.Adapter(value[0])]
# Getting the distance parameter in the units of the field.
params += self.get_distance(value[1:], lookup_type, connection)
else:
params = [connection.ops.Adapter(value)]
return params
def get_db_prep_save(self, value, connection):
"Prepares the value for saving in the database."
if not value:
return None
else:
return connection.ops.Adapter(self.get_prep_value(value))
for klass in gis_lookups.values():
GeometryField.register_lookup(klass)
# The OpenGIS Geometry Type Fields
class PointField(GeometryField):
geom_type = 'POINT'
form_class = forms.PointField
description = _("Point")
class LineStringField(GeometryField):
geom_type = 'LINESTRING'
form_class = forms.LineStringField
description = _("Line string")
raise ValueError(
'Cannot use object with type %s for a spatial lookup parameter.'
% type(obj).__name__)
# Assigning the SRID value.
obj.srid = self.get_srid(obj)
if seq_value:
lookup_val = [obj]
lookup_val.extend(value[1:])
return tuple(lookup_val)
else:
return obj
for klass in gis_lookups.values():
BaseSpatialField.register_lookup(klass)
class GeometryField(GeoSelectFormatMixin, BaseSpatialField):
"""
The base Geometry field -- maps to the OpenGIS Specification Geometry type.
"""
description = _(
"The base Geometry field -- maps to the OpenGIS Specification Geometry type."
)
form_class = forms.GeometryField
# The OpenGIS Geometry name.
geom_type = 'GEOMETRY'
def __init__(self, verbose_name=None, dim=2, geography=False, **kwargs):
