618 lines
28 KiB
Python
618 lines
28 KiB
Python
from django.core.exceptions import ImproperlyConfigured
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from django.db import connection
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from django.db.models.query import sql, QuerySet, Q
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from django.contrib.gis.db.backend import SpatialBackend
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from django.contrib.gis.db.models.fields import GeometryField, PointField
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from django.contrib.gis.db.models.sql import AreaField, DistanceField, GeomField, GeoQuery, GeoWhereNode
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from django.contrib.gis.measure import Area, Distance
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from django.contrib.gis.models import get_srid_info
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qn = connection.ops.quote_name
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# For backwards-compatibility; Q object should work just fine
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# after queryset-refactor.
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class GeoQ(Q): pass
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class GeomSQL(object):
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"Simple wrapper object for geometric SQL."
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def __init__(self, geo_sql):
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self.sql = geo_sql
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def as_sql(self, *args, **kwargs):
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return self.sql
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class GeoQuerySet(QuerySet):
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"The Geographic QuerySet."
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def __init__(self, model=None, query=None):
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super(GeoQuerySet, self).__init__(model=model, query=query)
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self.query = query or GeoQuery(self.model, connection)
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def area(self, tolerance=0.05, **kwargs):
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"""
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Returns the area of the geographic field in an `area` attribute on
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each element of this GeoQuerySet.
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"""
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# Peforming setup here rather than in `_spatial_attribute` so that
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# we can get the units for `AreaField`.
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procedure_args, geo_field = self._spatial_setup('area', field_name=kwargs.get('field_name', None))
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s = {'procedure_args' : procedure_args,
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'geo_field' : geo_field,
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'setup' : False,
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}
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if SpatialBackend.oracle:
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s['procedure_fmt'] = '%(geo_col)s,%(tolerance)s'
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s['procedure_args']['tolerance'] = tolerance
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s['select_field'] = AreaField('sq_m') # Oracle returns area in units of meters.
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elif SpatialBackend.postgis:
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if not geo_field.geodetic:
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# Getting the area units of the geographic field.
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s['select_field'] = AreaField(Area.unit_attname(geo_field._unit_name))
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else:
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# TODO: Do we want to support raw number areas for geodetic fields?
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raise Exception('Area on geodetic coordinate systems not supported.')
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return self._spatial_attribute('area', s, **kwargs)
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def centroid(self, **kwargs):
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"""
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Returns the centroid of the geographic field in a `centroid`
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attribute on each element of this GeoQuerySet.
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"""
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return self._geom_attribute('centroid', **kwargs)
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def difference(self, geom, **kwargs):
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"""
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Returns the spatial difference of the geographic field in a `difference`
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attribute on each element of this GeoQuerySet.
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"""
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return self._geomset_attribute('difference', geom, **kwargs)
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def distance(self, geom, **kwargs):
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"""
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Returns the distance from the given geographic field name to the
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given geometry in a `distance` attribute on each element of the
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GeoQuerySet.
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Keyword Arguments:
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`spheroid` => If the geometry field is geodetic and PostGIS is
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the spatial database, then the more accurate
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spheroid calculation will be used instead of the
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quicker sphere calculation.
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`tolerance` => Used only for Oracle. The tolerance is
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in meters -- a default of 5 centimeters (0.05)
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is used.
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"""
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return self._distance_attribute('distance', geom, **kwargs)
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def envelope(self, **kwargs):
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"""
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Returns a Geometry representing the bounding box of the
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Geometry field in an `envelope` attribute on each element of
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the GeoQuerySet.
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"""
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return self._geom_attribute('envelope', **kwargs)
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def extent(self, **kwargs):
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"""
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Returns the extent (aggregate) of the features in the GeoQuerySet. The
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extent will be returned as a 4-tuple, consisting of (xmin, ymin, xmax, ymax).
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"""
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convert_extent = None
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if SpatialBackend.postgis:
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def convert_extent(box, geo_field):
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# TODO: Parsing of BOX3D, Oracle support (patches welcome!)
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# Box text will be something like "BOX(-90.0 30.0, -85.0 40.0)";
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# parsing out and returning as a 4-tuple.
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ll, ur = box[4:-1].split(',')
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xmin, ymin = map(float, ll.split())
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xmax, ymax = map(float, ur.split())
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return (xmin, ymin, xmax, ymax)
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elif SpatialBackend.oracle:
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def convert_extent(wkt, geo_field):
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raise NotImplementedError
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return self._spatial_aggregate('extent', convert_func=convert_extent, **kwargs)
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def gml(self, precision=8, version=2, **kwargs):
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"""
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Returns GML representation of the given field in a `gml` attribute
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on each element of the GeoQuerySet.
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"""
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s = {'desc' : 'GML', 'procedure_args' : {'precision' : precision}}
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if SpatialBackend.postgis:
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# PostGIS AsGML() aggregate function parameter order depends on the
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# version -- uggh.
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major, minor1, minor2 = SpatialBackend.version
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if major >= 1 and (minor1 > 3 or (minor1 == 3 and minor2 > 1)):
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procedure_fmt = '%(version)s,%(geo_col)s,%(precision)s'
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else:
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procedure_fmt = '%(geo_col)s,%(precision)s,%(version)s'
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s['procedure_args'] = {'precision' : precision, 'version' : version}
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return self._spatial_attribute('gml', s, **kwargs)
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def intersection(self, geom, **kwargs):
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"""
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Returns the spatial intersection of the Geometry field in
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an `intersection` attribute on each element of this
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GeoQuerySet.
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"""
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return self._geomset_attribute('intersection', geom, **kwargs)
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def kml(self, **kwargs):
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"""
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Returns KML representation of the geometry field in a `kml`
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attribute on each element of this GeoQuerySet.
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"""
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s = {'desc' : 'KML',
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'procedure_fmt' : '%(geo_col)s,%(precision)s',
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'procedure_args' : {'precision' : kwargs.pop('precision', 8)},
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}
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return self._spatial_attribute('kml', s, **kwargs)
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def length(self, **kwargs):
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"""
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Returns the length of the geometry field as a `Distance` object
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stored in a `length` attribute on each element of this GeoQuerySet.
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"""
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return self._distance_attribute('length', None, **kwargs)
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def make_line(self, **kwargs):
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"""
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Creates a linestring from all of the PointField geometries in the
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this GeoQuerySet and returns it. This is a spatial aggregate
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method, and thus returns a geometry rather than a GeoQuerySet.
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"""
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kwargs['geo_field_type'] = PointField
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kwargs['agg_field'] = GeometryField
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return self._spatial_aggregate('make_line', **kwargs)
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def mem_size(self, **kwargs):
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"""
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Returns the memory size (number of bytes) that the geometry field takes
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in a `mem_size` attribute on each element of this GeoQuerySet.
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"""
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return self._spatial_attribute('mem_size', {}, **kwargs)
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def num_geom(self, **kwargs):
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"""
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Returns the number of geometries if the field is a
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GeometryCollection or Multi* Field in a `num_geom`
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attribute on each element of this GeoQuerySet; otherwise
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the sets with None.
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"""
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return self._spatial_attribute('num_geom', {}, **kwargs)
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def num_points(self, **kwargs):
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"""
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Returns the number of points in the first linestring in the
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Geometry field in a `num_points` attribute on each element of
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this GeoQuerySet; otherwise sets with None.
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"""
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return self._spatial_attribute('num_points', {}, **kwargs)
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def perimeter(self, **kwargs):
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"""
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Returns the perimeter of the geometry field as a `Distance` object
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stored in a `perimeter` attribute on each element of this GeoQuerySet.
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"""
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return self._distance_attribute('perimeter', None, **kwargs)
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def point_on_surface(self, **kwargs):
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"""
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Returns a Point geometry guaranteed to lie on the surface of the
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Geometry field in a `point_on_surface` attribute on each element
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of this GeoQuerySet; otherwise sets with None.
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"""
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return self._geom_attribute('point_on_surface', **kwargs)
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def scale(self, x, y, z=0.0, **kwargs):
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"""
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Scales the geometry to a new size by multiplying the ordinates
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with the given x,y,z scale factors.
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"""
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s = {'procedure_fmt' : '%(geo_col)s,%(x)s,%(y)s,%(z)s',
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'procedure_args' : {'x' : x, 'y' : y, 'z' : z},
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'select_field' : GeomField(),
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}
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return self._spatial_attribute('scale', s, **kwargs)
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def svg(self, **kwargs):
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"""
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Returns SVG representation of the geographic field in a `svg`
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attribute on each element of this GeoQuerySet.
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"""
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s = {'desc' : 'SVG',
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'procedure_fmt' : '%(geo_col)s,%(rel)s,%(precision)s',
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'procedure_args' : {'rel' : int(kwargs.pop('relative', 0)),
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'precision' : kwargs.pop('precision', 8)},
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}
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return self._spatial_attribute('svg', s, **kwargs)
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def sym_difference(self, geom, **kwargs):
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"""
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Returns the symmetric difference of the geographic field in a
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`sym_difference` attribute on each element of this GeoQuerySet.
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"""
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return self._geomset_attribute('sym_difference', geom, **kwargs)
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def translate(self, x, y, z=0.0, **kwargs):
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"""
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Translates the geometry to a new location using the given numeric
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parameters as offsets.
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"""
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s = {'procedure_fmt' : '%(geo_col)s,%(x)s,%(y)s,%(z)s',
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'procedure_args' : {'x' : x, 'y' : y, 'z' : z},
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'select_field' : GeomField(),
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}
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return self._spatial_attribute('translate', s, **kwargs)
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def transform(self, srid=4326, **kwargs):
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"""
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Transforms the given geometry field to the given SRID. If no SRID is
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provided, the transformation will default to using 4326 (WGS84).
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"""
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if not isinstance(srid, (int, long)):
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raise TypeError('An integer SRID must be provided.')
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field_name = kwargs.get('field_name', None)
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tmp, geo_field = self._spatial_setup('transform', field_name=field_name)
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# Getting the selection SQL for the given geographic field.
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field_col = self._geocol_select(geo_field, field_name)
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# Why cascading substitutions? Because spatial backends like
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# Oracle and MySQL already require a function call to convert to text, thus
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# when there's also a transformation we need to cascade the substitutions.
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# For example, 'SDO_UTIL.TO_WKTGEOMETRY(SDO_CS.TRANSFORM( ... )'
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geo_col = self.query.custom_select.get(geo_field, field_col)
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# Setting the key for the field's column with the custom SELECT SQL to
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# override the geometry column returned from the database.
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custom_sel = '%s(%s, %s)' % (SpatialBackend.transform, geo_col, srid)
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# TODO: Should we have this as an alias?
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# custom_sel = '(%s(%s, %s)) AS %s' % (SpatialBackend.transform, geo_col, srid, qn(geo_field.name))
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self.query.transformed_srid = srid # So other GeoQuerySet methods
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self.query.custom_select[geo_field] = custom_sel
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return self._clone()
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def union(self, geom, **kwargs):
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"""
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Returns the union of the geographic field with the given
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Geometry in a `union` attribute on each element of this GeoQuerySet.
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"""
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return self._geomset_attribute('union', geom, **kwargs)
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def unionagg(self, **kwargs):
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"""
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Performs an aggregate union on the given geometry field. Returns
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None if the GeoQuerySet is empty. The `tolerance` keyword is for
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Oracle backends only.
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"""
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kwargs['agg_field'] = GeometryField
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return self._spatial_aggregate('unionagg', **kwargs)
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### Private API -- Abstracted DRY routines. ###
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def _spatial_setup(self, att, aggregate=False, desc=None, field_name=None, geo_field_type=None):
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"""
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Performs set up for executing the spatial function.
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"""
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# Does the spatial backend support this?
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func = getattr(SpatialBackend, att, False)
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if desc is None: desc = att
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if not func: raise ImproperlyConfigured('%s stored procedure not available.' % desc)
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# Initializing the procedure arguments.
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procedure_args = {'function' : func}
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# Is there a geographic field in the model to perform this
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# operation on?
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geo_field = self.query._geo_field(field_name)
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if not geo_field:
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raise TypeError('%s output only available on GeometryFields.' % func)
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# If the `geo_field_type` keyword was used, then enforce that
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# type limitation.
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if not geo_field_type is None and not isinstance(geo_field, geo_field_type):
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raise TypeError('"%s" stored procedures may only be called on %ss.' % (func, geo_field_type.__name__))
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# Setting the procedure args.
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procedure_args['geo_col'] = self._geocol_select(geo_field, field_name, aggregate)
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return procedure_args, geo_field
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def _spatial_aggregate(self, att, field_name=None,
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agg_field=None, convert_func=None,
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geo_field_type=None, tolerance=0.0005):
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"""
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DRY routine for calling aggregate spatial stored procedures and
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returning their result to the caller of the function.
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"""
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# Constructing the setup keyword arguments.
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setup_kwargs = {'aggregate' : True,
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'field_name' : field_name,
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'geo_field_type' : geo_field_type,
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}
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procedure_args, geo_field = self._spatial_setup(att, **setup_kwargs)
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if SpatialBackend.oracle:
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procedure_args['tolerance'] = tolerance
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# Adding in selection SQL for Oracle geometry columns.
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if agg_field is GeometryField:
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agg_sql = '%s' % SpatialBackend.select
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else:
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agg_sql = '%s'
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agg_sql = agg_sql % ('%(function)s(SDOAGGRTYPE(%(geo_col)s,%(tolerance)s))' % procedure_args)
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else:
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agg_sql = '%(function)s(%(geo_col)s)' % procedure_args
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# Wrapping our selection SQL in `GeomSQL` to bypass quoting, and
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# specifying the type of the aggregate field.
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self.query.select = [GeomSQL(agg_sql)]
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self.query.select_fields = [agg_field]
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try:
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# `asql` => not overriding `sql` module.
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asql, params = self.query.as_sql()
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except sql.datastructures.EmptyResultSet:
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return None
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# Getting a cursor, executing the query, and extracting the returned
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# value from the aggregate function.
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cursor = connection.cursor()
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cursor.execute(asql, params)
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result = cursor.fetchone()[0]
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# If the `agg_field` is specified as a GeometryField, then autmatically
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# set up the conversion function.
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if agg_field is GeometryField and not callable(convert_func):
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if SpatialBackend.postgis:
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def convert_geom(hex, geo_field):
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if hex: return SpatialBackend.Geometry(hex)
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else: return None
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elif SpatialBackend.oracle:
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def convert_geom(clob, geo_field):
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if clob: return SpatialBackend.Geometry(clob.read(), geo_field._srid)
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else: return None
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convert_func = convert_geom
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# Returning the callback function evaluated on the result culled
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# from the executed cursor.
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if callable(convert_func):
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return convert_func(result, geo_field)
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else:
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return result
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def _spatial_attribute(self, att, settings, field_name=None, model_att=None):
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"""
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DRY routine for calling a spatial stored procedure on a geometry column
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and attaching its output as an attribute of the model.
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Arguments:
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att:
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The name of the spatial attribute that holds the spatial
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SQL function to call.
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settings:
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Dictonary of internal settings to customize for the spatial procedure.
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Public Keyword Arguments:
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field_name:
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The name of the geographic field to call the spatial
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function on. May also be a lookup to a geometry field
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as part of a foreign key relation.
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model_att:
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The name of the model attribute to attach the output of
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the spatial function to.
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"""
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# Default settings.
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settings.setdefault('desc', None)
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settings.setdefault('geom_args', ())
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settings.setdefault('geom_field', None)
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settings.setdefault('procedure_args', {})
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settings.setdefault('procedure_fmt', '%(geo_col)s')
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settings.setdefault('select_params', [])
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# Performing setup for the spatial column, unless told not to.
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if settings.get('setup', True):
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default_args, geo_field = self._spatial_setup(att, desc=settings['desc'], field_name=field_name)
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for k, v in default_args.iteritems(): settings['procedure_args'].setdefault(k, v)
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else:
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geo_field = settings['geo_field']
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# The attribute to attach to the model.
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if not isinstance(model_att, basestring): model_att = att
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# Special handling for any argument that is a geometry.
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for name in settings['geom_args']:
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# Using the field's get_db_prep_lookup() to get any needed
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# transformation SQL -- we pass in a 'dummy' `contains` lookup.
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where, params = geo_field.get_db_prep_lookup('contains', settings['procedure_args'][name])
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# Replacing the procedure format with that of any needed
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# transformation SQL.
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old_fmt = '%%(%s)s' % name
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new_fmt = where[0] % '%%s'
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settings['procedure_fmt'] = settings['procedure_fmt'].replace(old_fmt, new_fmt)
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settings['select_params'].extend(params)
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# Getting the format for the stored procedure.
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fmt = '%%(function)s(%s)' % settings['procedure_fmt']
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# If the result of this function needs to be converted.
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if settings.get('select_field', False):
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sel_fld = settings['select_field']
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if isinstance(sel_fld, GeomField) and SpatialBackend.select:
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self.query.custom_select[model_att] = SpatialBackend.select
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self.query.extra_select_fields[model_att] = sel_fld
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# Finally, setting the extra selection attribute with
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# the format string expanded with the stored procedure
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# arguments.
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return self.extra(select={model_att : fmt % settings['procedure_args']},
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select_params=settings['select_params'])
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def _distance_attribute(self, func, geom=None, tolerance=0.05, spheroid=False, **kwargs):
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"""
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DRY routine for GeoQuerySet distance attribute routines.
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"""
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# Setting up the distance procedure arguments.
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procedure_args, geo_field = self._spatial_setup(func, field_name=kwargs.get('field_name', None))
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# If geodetic defaulting distance attribute to meters (Oracle and
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# PostGIS spherical distances return meters). Otherwise, use the
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# units of the geometry field.
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if geo_field.geodetic:
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dist_att = 'm'
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else:
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dist_att = Distance.unit_attname(geo_field._unit_name)
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# Shortcut booleans for what distance function we're using.
|
|
distance = func == 'distance'
|
|
length = func == 'length'
|
|
perimeter = func == 'perimeter'
|
|
if not (distance or length or perimeter):
|
|
raise ValueError('Unknown distance function: %s' % func)
|
|
|
|
# The field's get_db_prep_lookup() is used to get any
|
|
# extra distance parameters. Here we set up the
|
|
# parameters that will be passed in to field's function.
|
|
lookup_params = [geom or 'POINT (0 0)', 0]
|
|
|
|
# If the spheroid calculation is desired, either by the `spheroid`
|
|
# keyword or wehn calculating the length of geodetic field, make
|
|
# sure the 'spheroid' distance setting string is passed in so we
|
|
# get the correct spatial stored procedure.
|
|
if spheroid or (SpatialBackend.postgis and geo_field.geodetic and length):
|
|
lookup_params.append('spheroid')
|
|
where, params = geo_field.get_db_prep_lookup('distance_lte', lookup_params)
|
|
|
|
# The `geom_args` flag is set to true if a geometry parameter was
|
|
# passed in.
|
|
geom_args = bool(geom)
|
|
|
|
if SpatialBackend.oracle:
|
|
if distance:
|
|
procedure_fmt = '%(geo_col)s,%(geom)s,%(tolerance)s'
|
|
elif length or perimeter:
|
|
procedure_fmt = '%(geo_col)s,%(tolerance)s'
|
|
procedure_args['tolerance'] = tolerance
|
|
else:
|
|
# Getting whether this field is in units of degrees since the field may have
|
|
# been transformed via the `transform` GeoQuerySet method.
|
|
if self.query.transformed_srid:
|
|
u, unit_name, s = get_srid_info(self.query.transformed_srid)
|
|
geodetic = unit_name in geo_field.geodetic_units
|
|
else:
|
|
geodetic = geo_field.geodetic
|
|
|
|
if distance:
|
|
if self.query.transformed_srid:
|
|
# Setting the `geom_args` flag to false because we want to handle
|
|
# transformation SQL here, rather than the way done by default
|
|
# (which will transform to the original SRID of the field rather
|
|
# than to what was transformed to).
|
|
geom_args = False
|
|
procedure_fmt = '%s(%%(geo_col)s, %s)' % (SpatialBackend.transform, self.query.transformed_srid)
|
|
if geom.srid is None or geom.srid == self.query.transformed_srid:
|
|
# If the geom parameter srid is None, it is assumed the coordinates
|
|
# are in the transformed units. A placeholder is used for the
|
|
# geometry parameter.
|
|
procedure_fmt += ', %%s'
|
|
else:
|
|
# We need to transform the geom to the srid specified in `transform()`,
|
|
# so wrapping the geometry placeholder in transformation SQL.
|
|
procedure_fmt += ', %s(%%%%s, %s)' % (SpatialBackend.transform, self.query.transformed_srid)
|
|
else:
|
|
# `transform()` was not used on this GeoQuerySet.
|
|
procedure_fmt = '%(geo_col)s,%(geom)s'
|
|
|
|
if geodetic:
|
|
# Spherical distance calculation is needed (because the geographic
|
|
# field is geodetic). However, the PostGIS ST_distance_sphere/spheroid()
|
|
# procedures may only do queries from point columns to point geometries
|
|
# some error checking is required.
|
|
if not isinstance(geo_field, PointField):
|
|
raise TypeError('Spherical distance calculation only supported on PointFields.')
|
|
if not str(SpatialBackend.Geometry(buffer(params[0].wkb)).geom_type) == 'Point':
|
|
raise TypeError('Spherical distance calculation only supported with Point Geometry parameters')
|
|
# The `function` procedure argument needs to be set differently for
|
|
# geodetic distance calculations.
|
|
if spheroid:
|
|
# Call to distance_spheroid() requires spheroid param as well.
|
|
procedure_fmt += ',%(spheroid)s'
|
|
procedure_args.update({'function' : SpatialBackend.distance_spheroid, 'spheroid' : where[1]})
|
|
else:
|
|
procedure_args.update({'function' : SpatialBackend.distance_sphere})
|
|
elif length or perimeter:
|
|
procedure_fmt = '%(geo_col)s'
|
|
if geodetic and length:
|
|
# There's no `length_sphere`
|
|
procedure_fmt += ',%(spheroid)s'
|
|
procedure_args.update({'function' : SpatialBackend.length_spheroid, 'spheroid' : where[1]})
|
|
|
|
# Setting up the settings for `_spatial_attribute`.
|
|
s = {'select_field' : DistanceField(dist_att),
|
|
'setup' : False,
|
|
'geo_field' : geo_field,
|
|
'procedure_args' : procedure_args,
|
|
'procedure_fmt' : procedure_fmt,
|
|
}
|
|
if geom_args:
|
|
s['geom_args'] = ('geom',)
|
|
s['procedure_args']['geom'] = geom
|
|
elif geom:
|
|
# The geometry is passed in as a parameter because we handled
|
|
# transformation conditions in this routine.
|
|
s['select_params'] = [SpatialBackend.Adaptor(geom)]
|
|
return self._spatial_attribute(func, s, **kwargs)
|
|
|
|
def _geom_attribute(self, func, tolerance=0.05, **kwargs):
|
|
"""
|
|
DRY routine for setting up a GeoQuerySet method that attaches a
|
|
Geometry attribute (e.g., `centroid`, `point_on_surface`).
|
|
"""
|
|
s = {'select_field' : GeomField(),}
|
|
if SpatialBackend.oracle:
|
|
s['procedure_fmt'] = '%(geo_col)s,%(tolerance)s'
|
|
s['procedure_args'] = {'tolerance' : tolerance}
|
|
return self._spatial_attribute(func, s, **kwargs)
|
|
|
|
def _geomset_attribute(self, func, geom, tolerance=0.05, **kwargs):
|
|
"""
|
|
DRY routine for setting up a GeoQuerySet method that attaches a
|
|
Geometry attribute and takes a Geoemtry parameter. This is used
|
|
for geometry set-like operations (e.g., intersection, difference,
|
|
union, sym_difference).
|
|
"""
|
|
s = {'geom_args' : ('geom',),
|
|
'select_field' : GeomField(),
|
|
'procedure_fmt' : '%(geo_col)s,%(geom)s',
|
|
'procedure_args' : {'geom' : geom},
|
|
}
|
|
if SpatialBackend.oracle:
|
|
s['procedure_fmt'] += ',%(tolerance)s'
|
|
s['procedure_args']['tolerance'] = tolerance
|
|
return self._spatial_attribute(func, s, **kwargs)
|
|
|
|
def _geocol_select(self, geo_field, field_name, aggregate=False):
|
|
"""
|
|
Helper routine for constructing the SQL to select the geographic
|
|
column. Takes into account if the geographic field is in a
|
|
ForeignKey relation to the current model.
|
|
"""
|
|
# If this is an aggregate spatial query, the flag needs to be
|
|
# set on the `GeoQuery` object of this queryset.
|
|
if aggregate: self.query.aggregate = True
|
|
|
|
# Is this operation going to be on a related geographic field?
|
|
if not geo_field in self.model._meta.fields:
|
|
# If so, it'll have to be added to the select related information
|
|
# (e.g., if 'location__point' was given as the field name).
|
|
self.query.add_select_related([field_name])
|
|
self.query.pre_sql_setup()
|
|
rel_table, rel_col = self.query.related_select_cols[self.query.related_select_fields.index(geo_field)]
|
|
return self.query._field_column(geo_field, rel_table)
|
|
else:
|
|
return self.query._field_column(geo_field)
|