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from django.contrib.gis.db.models.fields import ExtentField
from django.db.models import Value
from django.db.models.aggregates import Aggregate
__all__ = ['Collect', 'Extent', 'Extent3D', 'MakeLine', 'Union']
class GeoAggregate(Aggregate):
function = None
is_extent = False
def as_sql(self, compiler, connection):
# this will be called again in parent, but it's needed now - before
# we get the spatial_aggregate_name
connection.ops.check_expression_support(self)
self.function = connection.ops.spatial_aggregate_name(self.name)
return super(GeoAggregate, self).as_sql(compiler, connection)
def as_oracle(self, compiler, connection):
if not self.is_extent:
tolerance = self.extra.get('tolerance') or getattr(self, 'tolerance', 0.05)
clone = self.copy()
expressions = clone.get_source_expressions()
expressions.append(Value(tolerance))
clone.set_source_expressions(expressions)
clone.template = '%(function)s(SDOAGGRTYPE(%(expressions)s))'
return clone.as_sql(compiler, connection)
return self.as_sql(compiler, connection)
def resolve_expression(self, query=None, allow_joins=True, reuse=None, summarize=False, for_save=False):
c = super(GeoAggregate, self).resolve_expression(query, allow_joins, reuse, summarize, for_save)
for expr in c.get_source_expressions():
if not hasattr(expr.field, 'geom_type'):
raise ValueError('Geospatial aggregates only allowed on geometry fields.')
return c
class Collect(GeoAggregate):
name = 'Collect'
class Extent(GeoAggregate):
name = 'Extent'
is_extent = '2D'
def __init__(self, expression, **extra):
super(Extent, self).__init__(expression, output_field=ExtentField(), **extra)
def convert_value(self, value, expression, connection, context):
return connection.ops.convert_extent(value, context.get('transformed_srid'))
class Extent3D(GeoAggregate):
name = 'Extent3D'
is_extent = '3D'
def __init__(self, expression, **extra):
super(Extent3D, self).__init__(expression, output_field=ExtentField(), **extra)
def convert_value(self, value, expression, connection, context):
return connection.ops.convert_extent3d(value, context.get('transformed_srid'))
class MakeLine(GeoAggregate):
name = 'MakeLine'
class Union(GeoAggregate):
name = 'Union'
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