65 lines
2.9 KiB
Python
65 lines
2.9 KiB
Python
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import datetime
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from django.db.models.fields import Field
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from django.db.models.sql.where import WhereNode
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from django.contrib.gis.db.backend import get_geo_where_clause, SpatialBackend
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class GeoAnnotation(object):
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"""
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The annotation used for GeometryFields; basically a placeholder
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for metadata needed by the `get_geo_where_clause` of the spatial
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backend.
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"""
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def __init__(self, field, value, where):
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self.geodetic = field.geodetic
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self.geom_type = field._geom
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self.value = value
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self.where = tuple(where)
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class GeoWhereNode(WhereNode):
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"""
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Used to represent the SQL where-clause for spatial databases --
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these are tied to the GeoQuery class that created it.
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"""
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def add(self, data, connector):
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"""
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This is overridden from the regular WhereNode to handle the
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peculiarties of GeometryFields, because they need a special
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annotation object that contains the spatial metadata from the
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field to generate the spatial SQL.
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"""
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if not isinstance(data, (list, tuple)):
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return super(WhereNode, self).add(data, connector)
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alias, col, field, lookup_type, value = data
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if not hasattr(field, "_geom"):
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# Not a geographic field, so call `WhereNode.add`.
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return super(GeoWhereNode, self).add(data, connector)
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else:
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# `GeometryField.get_db_prep_lookup` returns a where clause
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# substitution array in addition to the parameters.
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where, params = field.get_db_prep_lookup(lookup_type, value)
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# The annotation will be a `GeoAnnotation` object that
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# will contain the necessary geometry field metadata for
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# the `get_geo_where_clause` to construct the appropriate
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# spatial SQL when `make_atom` is called.
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annotation = GeoAnnotation(field, value, where)
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return super(WhereNode, self).add((alias, col, field.db_type(), lookup_type,
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annotation, params), connector)
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def make_atom(self, child, qn):
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table_alias, name, db_type, lookup_type, value_annot, params = child
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if isinstance(value_annot, GeoAnnotation):
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if lookup_type in SpatialBackend.gis_terms:
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# Getting the geographic where clause; substitution parameters
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# will be populated in the GeoFieldSQL object returned by the
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# GeometryField.
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gwc = get_geo_where_clause(table_alias, name, lookup_type, value_annot)
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return gwc % value_annot.where, params
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else:
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raise TypeError('Invalid lookup type: %r' % lookup_type)
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else:
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# If not a GeometryField, call the `make_atom` from the
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# base class.
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return super(GeoWhereNode, self).make_atom(child, qn)
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