314 lines
14 KiB
Python
314 lines
14 KiB
Python
"""
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This module contains the spatial lookup types, and the get_geo_where_clause()
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routine for PostGIS.
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"""
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import re
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from decimal import Decimal
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from django.db import connection
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from django.conf import settings
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from django.contrib.gis.measure import Distance
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from django.contrib.gis.db.backend.util import SpatialOperation, SpatialFunction
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qn = connection.ops.quote_name
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# Get the PostGIS version information.
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# To avoid the need to do a database query to determine the PostGIS version
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# each time the server starts up, one can optionally specify a
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# POSTGIS_VERSION setting. This setting is intentionally undocumented and
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# should be considered experimental, because an upcoming GIS backend
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# refactoring might remove the need for it.
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if hasattr(settings, 'POSTGIS_VERSION') and settings.POSTGIS_VERSION is not None:
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version_tuple = settings.POSTGIS_VERSION
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else:
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# This import is intentionally within the 'else' so that it isn't executed
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# if the POSTGIS_VERSION setting is available.
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from django.contrib.gis.db.backend.postgis.management import postgis_version_tuple
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version_tuple = postgis_version_tuple()
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POSTGIS_VERSION, MAJOR_VERSION, MINOR_VERSION1, MINOR_VERSION2 = version_tuple
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# The supported PostGIS versions.
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# TODO: Confirm tests with PostGIS versions 1.1.x -- should work.
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# Versions <= 1.0.x do not use GEOS C API, and will not be supported.
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if MAJOR_VERSION != 1 or (MAJOR_VERSION == 1 and MINOR_VERSION1 < 1):
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raise Exception('PostGIS version %s not supported.' % POSTGIS_VERSION)
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# Versions of PostGIS >= 1.2.2 changed their naming convention to be
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# 'SQL-MM-centric' to conform with the ISO standard. Practically, this
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# means that 'ST_' prefixes geometry function names.
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GEOM_FUNC_PREFIX = ''
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if MAJOR_VERSION >= 1:
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if (MINOR_VERSION1 > 2 or
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(MINOR_VERSION1 == 2 and MINOR_VERSION2 >= 2)):
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GEOM_FUNC_PREFIX = 'ST_'
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def get_func(func): return '%s%s' % (GEOM_FUNC_PREFIX, func)
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# Custom selection not needed for PostGIS because GEOS geometries are
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# instantiated directly from the HEXEWKB returned by default. If
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# WKT is needed for some reason in the future, this value may be changed,
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# e.g,, 'AsText(%s)'.
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GEOM_SELECT = None
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# Functions used by the GeoManager & GeoQuerySet
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AREA = get_func('Area')
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ASGEOJSON = get_func('AsGeoJson')
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ASKML = get_func('AsKML')
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ASGML = get_func('AsGML')
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ASSVG = get_func('AsSVG')
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CENTROID = get_func('Centroid')
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COLLECT = get_func('Collect')
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DIFFERENCE = get_func('Difference')
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DISTANCE = get_func('Distance')
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DISTANCE_SPHERE = get_func('distance_sphere')
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DISTANCE_SPHEROID = get_func('distance_spheroid')
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ENVELOPE = get_func('Envelope')
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EXTENT = get_func('Extent')
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EXTENT3D = get_func('Extent3D')
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GEOM_FROM_TEXT = get_func('GeomFromText')
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GEOM_FROM_EWKB = get_func('GeomFromEWKB')
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GEOM_FROM_WKB = get_func('GeomFromWKB')
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INTERSECTION = get_func('Intersection')
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LENGTH = get_func('Length')
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LENGTH3D = get_func('Length3D')
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LENGTH_SPHEROID = get_func('length_spheroid')
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MAKE_LINE = get_func('MakeLine')
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MEM_SIZE = get_func('mem_size')
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NUM_GEOM = get_func('NumGeometries')
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NUM_POINTS = get_func('npoints')
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PERIMETER = get_func('Perimeter')
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PERIMETER3D = get_func('Perimeter3D')
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POINT_ON_SURFACE = get_func('PointOnSurface')
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SCALE = get_func('Scale')
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SNAP_TO_GRID = get_func('SnapToGrid')
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SYM_DIFFERENCE = get_func('SymDifference')
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TRANSFORM = get_func('Transform')
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TRANSLATE = get_func('Translate')
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# Special cases for union, KML, and GeoJSON methods.
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if MINOR_VERSION1 < 3:
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UNIONAGG = 'GeomUnion'
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UNION = 'Union'
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else:
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UNIONAGG = 'ST_Union'
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UNION = 'ST_Union'
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if MINOR_VERSION1 == 1:
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ASKML = False
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# Only 1.3.4+ have AsGeoJson.
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if (MINOR_VERSION1 < 3 or
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(MINOR_VERSION1 == 3 and MINOR_VERSION2 < 4)):
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ASGEOJSON = False
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else:
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raise NotImplementedError('PostGIS versions < 1.0 are not supported.')
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#### Classes used in constructing PostGIS spatial SQL ####
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class PostGISOperator(SpatialOperation):
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"For PostGIS operators (e.g. `&&`, `~`)."
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def __init__(self, operator):
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super(PostGISOperator, self).__init__(operator=operator, beg_subst='%s %s %%s')
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class PostGISFunction(SpatialFunction):
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"For PostGIS function calls (e.g., `ST_Contains(table, geom)`)."
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def __init__(self, function, **kwargs):
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super(PostGISFunction, self).__init__(get_func(function), **kwargs)
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class PostGISFunctionParam(PostGISFunction):
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"For PostGIS functions that take another parameter (e.g. DWithin, Relate)."
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def __init__(self, func):
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super(PostGISFunctionParam, self).__init__(func, end_subst=', %%s)')
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class PostGISDistance(PostGISFunction):
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"For PostGIS distance operations."
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dist_func = 'Distance'
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def __init__(self, operator):
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super(PostGISDistance, self).__init__(self.dist_func, end_subst=') %s %s',
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operator=operator, result='%%s')
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class PostGISSpheroidDistance(PostGISFunction):
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"For PostGIS spherical distance operations (using the spheroid)."
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dist_func = 'distance_spheroid'
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def __init__(self, operator):
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# An extra parameter in `end_subst` is needed for the spheroid string.
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super(PostGISSpheroidDistance, self).__init__(self.dist_func,
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beg_subst='%s(%s, %%s, %%s',
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end_subst=') %s %s',
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operator=operator, result='%%s')
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class PostGISSphereDistance(PostGISFunction):
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"For PostGIS spherical distance operations."
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dist_func = 'distance_sphere'
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def __init__(self, operator):
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super(PostGISSphereDistance, self).__init__(self.dist_func, end_subst=') %s %s',
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operator=operator, result='%%s')
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class PostGISRelate(PostGISFunctionParam):
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"For PostGIS Relate(<geom>, <pattern>) calls."
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pattern_regex = re.compile(r'^[012TF\*]{9}$')
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def __init__(self, pattern):
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if not self.pattern_regex.match(pattern):
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raise ValueError('Invalid intersection matrix pattern "%s".' % pattern)
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super(PostGISRelate, self).__init__('Relate')
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#### Lookup type mapping dictionaries of PostGIS operations. ####
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# PostGIS-specific operators. The commented descriptions of these
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# operators come from Section 6.2.2 of the official PostGIS documentation.
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POSTGIS_OPERATORS = {
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# The "&<" operator returns true if A's bounding box overlaps or
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# is to the left of B's bounding box.
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'overlaps_left' : PostGISOperator('&<'),
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# The "&>" operator returns true if A's bounding box overlaps or
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# is to the right of B's bounding box.
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'overlaps_right' : PostGISOperator('&>'),
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# The "<<" operator returns true if A's bounding box is strictly
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# to the left of B's bounding box.
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'left' : PostGISOperator('<<'),
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# The ">>" operator returns true if A's bounding box is strictly
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# to the right of B's bounding box.
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'right' : PostGISOperator('>>'),
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# The "&<|" operator returns true if A's bounding box overlaps or
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# is below B's bounding box.
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'overlaps_below' : PostGISOperator('&<|'),
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# The "|&>" operator returns true if A's bounding box overlaps or
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# is above B's bounding box.
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'overlaps_above' : PostGISOperator('|&>'),
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# The "<<|" operator returns true if A's bounding box is strictly
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# below B's bounding box.
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'strictly_below' : PostGISOperator('<<|'),
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# The "|>>" operator returns true if A's bounding box is strictly
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# above B's bounding box.
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'strictly_above' : PostGISOperator('|>>'),
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# The "~=" operator is the "same as" operator. It tests actual
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# geometric equality of two features. So if A and B are the same feature,
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# vertex-by-vertex, the operator returns true.
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'same_as' : PostGISOperator('~='),
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'exact' : PostGISOperator('~='),
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# The "@" operator returns true if A's bounding box is completely contained
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# by B's bounding box.
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'contained' : PostGISOperator('@'),
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# The "~" operator returns true if A's bounding box completely contains
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# by B's bounding box.
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'bbcontains' : PostGISOperator('~'),
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# The "&&" operator returns true if A's bounding box overlaps
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# B's bounding box.
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'bboverlaps' : PostGISOperator('&&'),
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}
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# For PostGIS >= 1.2.2 the following lookup types will do a bounding box query
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# first before calling the more computationally expensive GEOS routines (called
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# "inline index magic"):
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# 'touches', 'crosses', 'contains', 'intersects', 'within', 'overlaps', and
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# 'covers'.
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POSTGIS_GEOMETRY_FUNCTIONS = {
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'equals' : PostGISFunction('Equals'),
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'disjoint' : PostGISFunction('Disjoint'),
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'touches' : PostGISFunction('Touches'),
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'crosses' : PostGISFunction('Crosses'),
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'within' : PostGISFunction('Within'),
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'overlaps' : PostGISFunction('Overlaps'),
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'contains' : PostGISFunction('Contains'),
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'intersects' : PostGISFunction('Intersects'),
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'relate' : (PostGISRelate, basestring),
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}
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# Valid distance types and substitutions
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dtypes = (Decimal, Distance, float, int, long)
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def get_dist_ops(operator):
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"Returns operations for both regular and spherical distances."
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return (PostGISDistance(operator), PostGISSphereDistance(operator), PostGISSpheroidDistance(operator))
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DISTANCE_FUNCTIONS = {
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'distance_gt' : (get_dist_ops('>'), dtypes),
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'distance_gte' : (get_dist_ops('>='), dtypes),
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'distance_lt' : (get_dist_ops('<'), dtypes),
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'distance_lte' : (get_dist_ops('<='), dtypes),
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}
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if GEOM_FUNC_PREFIX == 'ST_':
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# The ST_DWithin, ST_CoveredBy, and ST_Covers routines become available in 1.2.2+
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POSTGIS_GEOMETRY_FUNCTIONS.update(
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{'coveredby' : PostGISFunction('CoveredBy'),
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'covers' : PostGISFunction('Covers'),
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})
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DISTANCE_FUNCTIONS['dwithin'] = (PostGISFunctionParam('DWithin'), dtypes)
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# Distance functions are a part of PostGIS geometry functions.
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POSTGIS_GEOMETRY_FUNCTIONS.update(DISTANCE_FUNCTIONS)
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# Any other lookup types that do not require a mapping.
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MISC_TERMS = ['isnull']
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# These are the PostGIS-customized QUERY_TERMS -- a list of the lookup types
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# allowed for geographic queries.
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POSTGIS_TERMS = POSTGIS_OPERATORS.keys() # Getting the operators first
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POSTGIS_TERMS += POSTGIS_GEOMETRY_FUNCTIONS.keys() # Adding on the Geometry Functions
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POSTGIS_TERMS += MISC_TERMS # Adding any other miscellaneous terms (e.g., 'isnull')
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POSTGIS_TERMS = dict((term, None) for term in POSTGIS_TERMS) # Making a dictionary for fast lookups
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# For checking tuple parameters -- not very pretty but gets job done.
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def exactly_two(val): return val == 2
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def two_to_three(val): return val >= 2 and val <=3
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def num_params(lookup_type, val):
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if lookup_type in DISTANCE_FUNCTIONS and lookup_type != 'dwithin': return two_to_three(val)
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else: return exactly_two(val)
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#### The `get_geo_where_clause` function for PostGIS. ####
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def get_geo_where_clause(table_alias, name, lookup_type, geo_annot):
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"Returns the SQL WHERE clause for use in PostGIS SQL construction."
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# Getting the quoted field as `geo_col`.
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geo_col = '%s.%s' % (qn(table_alias), qn(name))
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if lookup_type in POSTGIS_OPERATORS:
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# See if a PostGIS operator matches the lookup type.
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return POSTGIS_OPERATORS[lookup_type].as_sql(geo_col)
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elif lookup_type in POSTGIS_GEOMETRY_FUNCTIONS:
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# See if a PostGIS geometry function matches the lookup type.
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tmp = POSTGIS_GEOMETRY_FUNCTIONS[lookup_type]
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# Lookup types that are tuples take tuple arguments, e.g., 'relate' and
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# distance lookups.
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if isinstance(tmp, tuple):
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# First element of tuple is the PostGISOperation instance, and the
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# second element is either the type or a tuple of acceptable types
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# that may passed in as further parameters for the lookup type.
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op, arg_type = tmp
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# Ensuring that a tuple _value_ was passed in from the user
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if not isinstance(geo_annot.value, (tuple, list)):
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raise TypeError('Tuple required for `%s` lookup type.' % lookup_type)
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# Number of valid tuple parameters depends on the lookup type.
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nparams = len(geo_annot.value)
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if not num_params(lookup_type, nparams):
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raise ValueError('Incorrect number of parameters given for `%s` lookup type.' % lookup_type)
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# Ensuring the argument type matches what we expect.
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if not isinstance(geo_annot.value[1], arg_type):
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raise TypeError('Argument type should be %s, got %s instead.' % (arg_type, type(geo_annot.value[1])))
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# For lookup type `relate`, the op instance is not yet created (has
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# to be instantiated here to check the pattern parameter).
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if lookup_type == 'relate':
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op = op(geo_annot.value[1])
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elif lookup_type in DISTANCE_FUNCTIONS and lookup_type != 'dwithin':
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if geo_annot.geodetic:
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# Geodetic distances are only availble from Points to PointFields.
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if geo_annot.geom_type != 'POINT':
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raise TypeError('PostGIS spherical operations are only valid on PointFields.')
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if geo_annot.value[0].geom_typeid != 0:
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raise TypeError('PostGIS geometry distance parameter is required to be of type Point.')
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# Setting up the geodetic operation appropriately.
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if nparams == 3 and geo_annot.value[2] == 'spheroid': op = op[2]
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else: op = op[1]
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else:
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op = op[0]
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else:
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op = tmp
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# Calling the `as_sql` function on the operation instance.
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return op.as_sql(geo_col)
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elif lookup_type == 'isnull':
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# Handling 'isnull' lookup type
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return "%s IS %sNULL" % (geo_col, (not geo_annot.value and 'NOT ' or ''))
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raise TypeError("Got invalid lookup_type: %s" % repr(lookup_type))
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