62 lines
1.8 KiB
Python
62 lines
1.8 KiB
Python
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.models.sql.conversion import GeomField
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class GeoAggregate(Aggregate):
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# Default SQL template for spatial aggregates.
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sql_template = '%(function)s(%(field)s)'
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# Conversion class, if necessary.
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conversion_class = None
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# Flags for indicating the type of the aggregate.
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is_extent = False
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def __init__(self, col, source=None, is_summary=False, tolerance=0.05, **extra):
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super(GeoAggregate, self).__init__(col, source, is_summary, **extra)
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# Required by some Oracle aggregates.
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self.tolerance = tolerance
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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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def as_sql(self, qn, connection):
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"Return the aggregate, rendered as SQL."
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if connection.ops.oracle:
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self.extra['tolerance'] = self.tolerance
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if hasattr(self.col, 'as_sql'):
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field_name = self.col.as_sql(qn, connection)
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elif isinstance(self.col, (list, tuple)):
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field_name = '.'.join([qn(c) for c in self.col])
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else:
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field_name = self.col
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sql_template, sql_function = connection.ops.spatial_aggregate_sql(self)
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params = {
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'function': sql_function,
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'field': field_name
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}
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params.update(self.extra)
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return sql_template % params
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class Collect(GeoAggregate):
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pass
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class Extent(GeoAggregate):
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is_extent = '2D'
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class Extent3D(GeoAggregate):
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is_extent = '3D'
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class MakeLine(GeoAggregate):
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pass
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class Union(GeoAggregate):
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pass
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