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0c7633178f
Refactored compiler SELECT, GROUP BY and ORDER BY generation. While there, also refactored select_related() implementation (get_cached_row() and get_klass_info() are now gone!). Made get_db_converters() method work on expressions instead of internal_type. This allows the backend converters to target specific expressions if need be. Added query.context, this can be used to set per-query state. Also changed the signature of database converters. They now accept context as an argument.
75 lines
1.9 KiB
Python
75 lines
1.9 KiB
Python
"""
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This module holds simple classes to convert geospatial values from the
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database.
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"""
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from django.contrib.gis.db.models.fields import GeoSelectFormatMixin
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from django.contrib.gis.geometry.backend import Geometry
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from django.contrib.gis.measure import Area, Distance
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class BaseField(object):
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empty_strings_allowed = True
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def get_db_converters(self, connection):
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return [self.from_db_value]
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def select_format(self, compiler, sql, params):
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return sql, params
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class AreaField(BaseField):
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"Wrapper for Area values."
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def __init__(self, area_att):
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self.area_att = area_att
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def from_db_value(self, value, connection, context):
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if value is not None:
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value = Area(**{self.area_att: value})
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return value
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def get_internal_type(self):
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return 'AreaField'
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class DistanceField(BaseField):
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"Wrapper for Distance values."
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def __init__(self, distance_att):
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self.distance_att = distance_att
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def from_db_value(self, value, connection, context):
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if value is not None:
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value = Distance(**{self.distance_att: value})
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return value
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def get_internal_type(self):
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return 'DistanceField'
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class GeomField(GeoSelectFormatMixin, BaseField):
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"""
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Wrapper for Geometry values. It is a lightweight alternative to
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using GeometryField (which requires an SQL query upon instantiation).
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"""
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# Hacky marker for get_db_converters()
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geom_type = None
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def from_db_value(self, value, connection, context):
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if value is not None:
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value = Geometry(value)
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return value
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def get_internal_type(self):
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return 'GeometryField'
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class GMLField(BaseField):
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"""
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Wrapper for GML to be used by Oracle to ensure Database.LOB conversion.
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"""
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def get_internal_type(self):
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return 'GMLField'
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def from_db_value(self, value, connection, context):
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return value
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