def __init__(self, verbose_name=None, srid=4326, spatial_index=True, dim=2, **kwargs):
"""
The initialization function for geometry fields. Takes the following
as keyword arguments:
srid:
The spatial reference system identifier, an OGC standard.
Defaults to 4326 (WGS84).
spatial_index:
Indicates whether to create a spatial index. Defaults to True.
Set this instead of 'db_index' for geographic fields since index
creation is different for geometry columns.
dim:
The number of dimensions for this geometry. Defaults to 2.
"""
# Setting the index flag with the value of the `spatial_index` keyword.
self._index = spatial_index
# Setting the SRID and getting the units. Unit information must be
# easily available in the field instance for distance queries.
self._srid = srid
self._unit, self._unit_name, self._spheroid = get_srid_info(srid)
# Setting the dimension of the geometry field.
self._dim = dim
# Setting the verbose_name keyword argument with the positional
# first parameter, so this works like normal fields.
kwargs['verbose_name'] = verbose_name
super(GeometryField, self).__init__(**kwargs) # Calling the parent initializtion function
def __init__(self, srid=4326, spatial_index=True, dim=2, **kwargs):
"""
The initialization function for geometry fields. Takes the following
as keyword arguments:
srid:
The spatial reference system identifier, an OGC standard.
Defaults to 4326 (WGS84).
spatial_index:
Indicates whether to create a spatial index. Defaults to True.
Set this instead of 'db_index' for geographic fields since index
creation is different for geometry columns.
dim:
The number of dimensions for this geometry. Defaults to 2.
"""
# Setting the index flag with the value of the `spatial_index` keyword.
self._index = spatial_index
# Setting the SRID and getting the units. Unit information must be
# easily available in the field instance for distance queries.
self._srid = srid
self._unit, self._unit_name, self._spheroid = get_srid_info(srid)
# Setting the dimension of the geometry field.
self._dim = dim
super(GeometryField, self).__init__(**kwargs) # Calling the parent initializtion function
def _distance_attribute(self,
func,
geom=None,
tolerance=0.05,
spheroid=False,
**kwargs):
"""
DRY routine for GeoQuerySet distance attribute routines.
"""
# Setting up the distance procedure arguments.
procedure_args, geo_field = self._spatial_setup(func,
field_name=kwargs.get(
'field_name',
None))
# If geodetic defaulting distance attribute to meters (Oracle and
# PostGIS spherical distances return meters). Otherwise, use the
# units of the geometry field.
if geo_field.geodetic:
dist_att = 'm'
else:
dist_att = Distance.unit_attname(geo_field._unit_name)
# Shortcut booleans for what distance function we're using.
distance = func == 'distance'
length = func == 'length'
perimeter = func == 'perimeter'
if not (distance or length or perimeter):
raise ValueError('Unknown distance function: %s' % func)
# The field's get_db_prep_lookup() is used to get any
# extra distance parameters. Here we set up the
# parameters that will be passed in to field's function.
lookup_params = [geom or 'POINT (0 0)', 0]
# If the spheroid calculation is desired, either by the `spheroid`
# keyword or wehn calculating the length of geodetic field, make
# sure the 'spheroid' distance setting string is passed in so we
# get the correct spatial stored procedure.
if spheroid or (SpatialBackend.postgis and geo_field.geodetic
and length):
lookup_params.append('spheroid')
where, params = geo_field.get_db_prep_lookup('distance_lte',
lookup_params)
# The `geom_args` flag is set to true if a geometry parameter was
# passed in.
geom_args = bool(geom)
if SpatialBackend.oracle:
if distance:
procedure_fmt = '%(geo_col)s,%(geom)s,%(tolerance)s'
elif length or perimeter:
procedure_fmt = '%(geo_col)s,%(tolerance)s'
procedure_args['tolerance'] = tolerance
else:
# Getting whether this field is in units of degrees since the field may have
# been transformed via the `transform` GeoQuerySet method.
if self.query.transformed_srid:
u, unit_name, s = get_srid_info(self.query.transformed_srid)
geodetic = unit_name in geo_field.geodetic_units
else:
geodetic = geo_field.geodetic
if distance:
if self.query.transformed_srid:
# Setting the `geom_args` flag to false because we want to handle
# transformation SQL here, rather than the way done by default
# (which will transform to the original SRID of the field rather
# than to what was transformed to).
geom_args = False
procedure_fmt = '%s(%%(geo_col)s, %s)' % (
SpatialBackend.transform, self.query.transformed_srid)
if geom.srid is None or geom.srid == self.query.transformed_srid:
# If the geom parameter srid is None, it is assumed the coordinates
# are in the transformed units. A placeholder is used for the
# geometry parameter.
procedure_fmt += ', %%s'
else:
# We need to transform the geom to the srid specified in `transform()`,
# so wrapping the geometry placeholder in transformation SQL.
procedure_fmt += ', %s(%%%%s, %s)' % (
SpatialBackend.transform,
self.query.transformed_srid)
else:
# `transform()` was not used on this GeoQuerySet.
procedure_fmt = '%(geo_col)s,%(geom)s'
if geodetic:
# Spherical distance calculation is needed (because the geographic
# field is geodetic). However, the PostGIS ST_distance_sphere/spheroid()
# procedures may only do queries from point columns to point geometries
# some error checking is required.
if not isinstance(geo_field, PointField):
raise TypeError(
'Spherical distance calculation only supported on PointFields.'
)
if not str(
SpatialBackend.Geometry(buffer(
params[0].wkb)).geom_type) == 'Point':
raise TypeError(
'Spherical distance calculation only supported with Point Geometry parameters'
)
# The `function` procedure argument needs to be set differently for
# geodetic distance calculations.
if spheroid:
# Call to distance_spheroid() requires spheroid param as well.
procedure_fmt += ',%(spheroid)s'
procedure_args.update({
'function': SpatialBackend.distance_spheroid,
'spheroid': where[1]
})
else:
procedure_args.update(
{'function': SpatialBackend.distance_sphere})
elif length or perimeter:
procedure_fmt = '%(geo_col)s'
if geodetic and length:
# There's no `length_sphere`
procedure_fmt += ',%(spheroid)s'
procedure_args.update({
'function': SpatialBackend.length_spheroid,
'spheroid': where[1]
})
# Setting up the settings for `_spatial_attribute`.
s = {
'select_field': DistanceField(dist_att),
'setup': False,
'geo_field': geo_field,
'procedure_args': procedure_args,
'procedure_fmt': procedure_fmt,
}
if geom_args:
s['geom_args'] = ('geom', )
s['procedure_args']['geom'] = geom
elif geom:
# The geometry is passed in as a parameter because we handled
# transformation conditions in this routine.
s['select_params'] = [SpatialBackend.Adaptor(geom)]
return self._spatial_attribute(func, s, **kwargs)
def _distance_attribute(self, func, geom=None, tolerance=0.05, spheroid=False, **kwargs):
"""
DRY routine for GeoQuerySet distance attribute routines.
"""
# Setting up the distance procedure arguments.
procedure_args, geo_field = self._spatial_setup(func, field_name=kwargs.get('field_name', None))
# If geodetic defaulting distance attribute to meters (Oracle and
# PostGIS spherical distances return meters). Otherwise, use the
# units of the geometry field.
if geo_field.geodetic:
dist_att = 'm'
else:
dist_att = Distance.unit_attname(geo_field._unit_name)
# Shortcut booleans for what distance function we're using.
distance = func == 'distance'
length = func == 'length'
perimeter = func == 'perimeter'
if not (distance or length or perimeter):
raise ValueError('Unknown distance function: %s' % func)
# The field's get_db_prep_lookup() is used to get any
# extra distance parameters. Here we set up the
# parameters that will be passed in to field's function.
lookup_params = [geom or 'POINT (0 0)', 0]
# If the spheroid calculation is desired, either by the `spheroid`
# keyword or wehn calculating the length of geodetic field, make
# sure the 'spheroid' distance setting string is passed in so we
# get the correct spatial stored procedure.
if spheroid or (SpatialBackend.postgis and geo_field.geodetic and length):
lookup_params.append('spheroid')
where, params = geo_field.get_db_prep_lookup('distance_lte', lookup_params)
# The `geom_args` flag is set to true if a geometry parameter was
# passed in.
geom_args = bool(geom)
if SpatialBackend.oracle:
if distance:
procedure_fmt = '%(geo_col)s,%(geom)s,%(tolerance)s'
elif length or perimeter:
procedure_fmt = '%(geo_col)s,%(tolerance)s'
procedure_args['tolerance'] = tolerance
else:
# Getting whether this field is in units of degrees since the field may have
# been transformed via the `transform` GeoQuerySet method.
if self.query.transformed_srid:
u, unit_name, s = get_srid_info(self.query.transformed_srid)
geodetic = unit_name in geo_field.geodetic_units
else:
geodetic = geo_field.geodetic
if distance:
if self.query.transformed_srid:
# Setting the `geom_args` flag to false because we want to handle
# transformation SQL here, rather than the way done by default
# (which will transform to the original SRID of the field rather
# than to what was transformed to).
geom_args = False
procedure_fmt = '%s(%%(geo_col)s, %s)' % (SpatialBackend.transform, self.query.transformed_srid)
if geom.srid is None or geom.srid == self.query.transformed_srid:
# If the geom parameter srid is None, it is assumed the coordinates
# are in the transformed units. A placeholder is used for the
# geometry parameter.
procedure_fmt += ', %%s'
else:
# We need to transform the geom to the srid specified in `transform()`,
# so wrapping the geometry placeholder in transformation SQL.
procedure_fmt += ', %s(%%%%s, %s)' % (SpatialBackend.transform, self.query.transformed_srid)
else:
# `transform()` was not used on this GeoQuerySet.
procedure_fmt = '%(geo_col)s,%(geom)s'
if geodetic:
# Spherical distance calculation is needed (because the geographic
# field is geodetic). However, the PostGIS ST_distance_sphere/spheroid()
# procedures may only do queries from point columns to point geometries
# some error checking is required.
if not isinstance(geo_field, PointField):
raise TypeError('Spherical distance calculation only supported on PointFields.')
if not str(SpatialBackend.Geometry(buffer(params[0].wkb)).geom_type) == 'Point':
raise TypeError('Spherical distance calculation only supported with Point Geometry parameters')
# The `function` procedure argument needs to be set differently for
# geodetic distance calculations.
if spheroid:
# Call to distance_spheroid() requires spheroid param as well.
procedure_fmt += ',%(spheroid)s'
procedure_args.update({'function' : SpatialBackend.distance_spheroid, 'spheroid' : where[1]})
else:
procedure_args.update({'function' : SpatialBackend.distance_sphere})
elif length or perimeter:
procedure_fmt = '%(geo_col)s'
if geodetic and length:
# There's no `length_sphere`
procedure_fmt += ',%(spheroid)s'
procedure_args.update({'function' : SpatialBackend.length_spheroid, 'spheroid' : where[1]})
# Setting up the settings for `_spatial_attribute`.
s = {'select_field' : DistanceField(dist_att),
'setup' : False,
'geo_field' : geo_field,
'procedure_args' : procedure_args,
'procedure_fmt' : procedure_fmt,
}
if geom_args:
s['geom_args'] = ('geom',)
s['procedure_args']['geom'] = geom
elif geom:
# The geometry is passed in as a parameter because we handled
# transformation conditions in this routine.
s['select_params'] = [SpatialBackend.Adaptor(geom)]
return self._spatial_attribute(func, s, **kwargs)
