37 lines
1.3 KiB
Python
37 lines
1.3 KiB
Python
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from django.db.models.sql.aggregates import *
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from django.contrib.gis.db.models.fields import GeometryField
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from django.contrib.gis.db.backend import SpatialBackend
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if SpatialBackend.oracle:
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geo_template = '%(function)s(SDOAGGRTYPE(%(field)s,%(tolerance)s))'
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else:
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geo_template = '%(function)s(%(field)s)'
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class GeoAggregate(Aggregate):
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# Overriding the SQL template with the geographic one.
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sql_template = geo_template
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is_extent = False
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def __init__(self, col, source=None, is_summary=False, **extra):
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super(GeoAggregate, self).__init__(col, source, is_summary, **extra)
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# Can't use geographic aggregates on non-geometry fields.
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if not isinstance(self.source, GeometryField):
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raise ValueError('Geospatial aggregates only allowed on geometry fields.')
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# Making sure the SQL function is available for this spatial backend.
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if not self.sql_function:
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raise NotImplementedError('This aggregate functionality not implemented for your spatial backend.')
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class Extent(GeoAggregate):
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is_extent = True
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sql_function = SpatialBackend.extent
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class MakeLine(GeoAggregate):
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sql_function = SpatialBackend.make_line
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class Union(GeoAggregate):
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sql_function = SpatialBackend.unionagg
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