136 lines
5.9 KiB
Python
136 lines
5.9 KiB
Python
from django.db import connection
|
|
from django.db.models.fields import Field
|
|
from django.db.models.sql.constants import LOOKUP_SEP
|
|
from django.db.models.sql.expressions import SQLEvaluator
|
|
from django.db.models.sql.where import WhereNode
|
|
from django.contrib.gis.db.backend import get_geo_where_clause, SpatialBackend
|
|
from django.contrib.gis.db.models.fields import GeometryField
|
|
qn = connection.ops.quote_name
|
|
|
|
class GeoAnnotation(object):
|
|
"""
|
|
The annotation used for GeometryFields; basically a placeholder
|
|
for metadata needed by the `get_geo_where_clause` of the spatial
|
|
backend.
|
|
"""
|
|
def __init__(self, field, value, where):
|
|
self.geodetic = field.geodetic
|
|
self.geom_type = field._geom
|
|
self.value = value
|
|
self.where = tuple(where)
|
|
|
|
class GeoWhereNode(WhereNode):
|
|
"""
|
|
Used to represent the SQL where-clause for spatial databases --
|
|
these are tied to the GeoQuery class that created it.
|
|
"""
|
|
def add(self, data, connector):
|
|
"""
|
|
This is overridden from the regular WhereNode to handle the
|
|
peculiarties of GeometryFields, because they need a special
|
|
annotation object that contains the spatial metadata from the
|
|
field to generate the spatial SQL.
|
|
"""
|
|
if not isinstance(data, (list, tuple)):
|
|
return super(WhereNode, self).add(data, connector)
|
|
|
|
obj, lookup_type, value = data
|
|
alias, col, field = obj.alias, obj.col, obj.field
|
|
|
|
if not hasattr(field, "_geom"):
|
|
# Not a geographic field, so call `WhereNode.add`.
|
|
return super(GeoWhereNode, self).add(data, connector)
|
|
else:
|
|
if isinstance(value, SQLEvaluator):
|
|
# Getting the geographic field to compare with from the expression.
|
|
geo_fld = self._check_geo_field(value.opts, value.expression.name)
|
|
if not geo_fld:
|
|
raise ValueError('No geographic field found in expression.')
|
|
|
|
# Get the SRID of the geometry field that the expression was meant
|
|
# to operate on -- it's needed to determine whether transformation
|
|
# SQL is necessary.
|
|
srid = geo_fld._srid
|
|
|
|
# Getting the quoted representation of the geometry column that
|
|
# the expression is operating on.
|
|
geo_col = '%s.%s' % tuple(map(qn, value.cols[value.expression]))
|
|
|
|
# If it's in a different SRID, we'll need to wrap in
|
|
# transformation SQL.
|
|
if not srid is None and srid != field._srid and SpatialBackend.transform:
|
|
placeholder = '%s(%%s, %s)' % (SpatialBackend.transform, field._srid)
|
|
else:
|
|
placeholder = '%s'
|
|
|
|
# Setting these up as if we had called `field.get_db_prep_lookup()`.
|
|
where = [placeholder % geo_col]
|
|
params = ()
|
|
else:
|
|
# `GeometryField.get_db_prep_lookup` returns a where clause
|
|
# substitution array in addition to the parameters.
|
|
where, params = field.get_db_prep_lookup(lookup_type, value)
|
|
|
|
# The annotation will be a `GeoAnnotation` object that
|
|
# will contain the necessary geometry field metadata for
|
|
# the `get_geo_where_clause` to construct the appropriate
|
|
# spatial SQL when `make_atom` is called.
|
|
annotation = GeoAnnotation(field, value, where)
|
|
return super(WhereNode, self).add((obj, lookup_type, annotation, params), connector)
|
|
|
|
def make_atom(self, child, qn):
|
|
lvalue, lookup_type, value_annot, params = child
|
|
|
|
if isinstance(value_annot, GeoAnnotation):
|
|
if lookup_type in SpatialBackend.gis_terms:
|
|
# Getting the geographic where clause; substitution parameters
|
|
# will be populated in the GeoFieldSQL object returned by the
|
|
# GeometryField.
|
|
gwc = get_geo_where_clause(lvalue.alias, lvalue.col, lookup_type, value_annot)
|
|
return gwc % value_annot.where, params
|
|
else:
|
|
raise TypeError('Invalid lookup type: %r' % lookup_type)
|
|
else:
|
|
# If not a GeometryField, call the `make_atom` from the
|
|
# base class.
|
|
return super(GeoWhereNode, self).make_atom(child, qn)
|
|
|
|
@classmethod
|
|
def _check_geo_field(cls, opts, lookup):
|
|
"""
|
|
Utility for checking the given lookup with the given model options.
|
|
The lookup is a string either specifying the geographic field, e.g.
|
|
'point, 'the_geom', or a related lookup on a geographic field like
|
|
'address__point'.
|
|
|
|
If a GeometryField exists according to the given lookup on the model
|
|
options, it will be returned. Otherwise returns None.
|
|
"""
|
|
# This takes into account the situation where the lookup is a
|
|
# lookup to a related geographic field, e.g., 'address__point'.
|
|
field_list = lookup.split(LOOKUP_SEP)
|
|
|
|
# Reversing so list operates like a queue of related lookups,
|
|
# and popping the top lookup.
|
|
field_list.reverse()
|
|
fld_name = field_list.pop()
|
|
|
|
try:
|
|
geo_fld = opts.get_field(fld_name)
|
|
# If the field list is still around, then it means that the
|
|
# lookup was for a geometry field across a relationship --
|
|
# thus we keep on getting the related model options and the
|
|
# model field associated with the next field in the list
|
|
# until there's no more left.
|
|
while len(field_list):
|
|
opts = geo_fld.rel.to._meta
|
|
geo_fld = opts.get_field(field_list.pop())
|
|
except (FieldDoesNotExist, AttributeError):
|
|
return False
|
|
|
|
# Finally, make sure we got a Geographic field and return.
|
|
if isinstance(geo_fld, GeometryField):
|
|
return geo_fld
|
|
else:
|
|
return False
|