from django.db.models.sql.aggregates import *
from django.contrib.gis.db.models.fields import GeometryField
from django.contrib.gis.db.models.sql.conversion import GeomField
class GeoAggregate(Aggregate):
# Default SQL template for spatial aggregates.
sql_template = '%(function)s(%(field)s)'
# Conversion class, if necessary.
conversion_class = None
# Flags for indicating the type of the aggregate.
is_extent = False
def __init__(self, col, source=None, is_summary=False, tolerance=0.05, **extra):
super(GeoAggregate, self).__init__(col, source, is_summary, **extra)
# Required by some Oracle aggregates.
self.tolerance = tolerance
# Can't use geographic aggregates on non-geometry fields.
if not isinstance(self.source, GeometryField):
raise ValueError('Geospatial aggregates only allowed on geometry fields.')
def as_sql(self, qn, connection):
"Return the aggregate, rendered as SQL."
if connection.ops.oracle:
self.extra['tolerance'] = self.tolerance
if hasattr(self.col, 'as_sql'):
field_name = self.col.as_sql(qn, connection)
elif isinstance(self.col, (list, tuple)):
field_name = '.'.join([qn(c) for c in self.col])
else:
field_name = self.col
sql_template, sql_function = connection.ops.spatial_aggregate_sql(self)
params = {
'function': sql_function,
'field': field_name
}
params.update(self.extra)
return sql_template % params
class Collect(GeoAggregate):
pass
class Extent(GeoAggregate):
is_extent = '2D'
class Extent3D(GeoAggregate):
is_extent = '3D'
class MakeLine(GeoAggregate):
pass
class Union(GeoAggregate):
pass
|