68 lines
2.2 KiB
Python
68 lines
2.2 KiB
Python
"""
|
|
This object provides quoting for GEOS geometries into PostgreSQL/PostGIS.
|
|
"""
|
|
from psycopg2 import Binary
|
|
from psycopg2.extensions import ISQLQuote
|
|
|
|
from django.contrib.gis.db.backends.postgis.pgraster import to_pgraster
|
|
from django.contrib.gis.geometry.backend import Geometry
|
|
|
|
|
|
class PostGISAdapter(object):
|
|
def __init__(self, obj, geography=False):
|
|
"""
|
|
Initialize on the spatial object.
|
|
"""
|
|
self.is_geometry = isinstance(obj, (Geometry, PostGISAdapter))
|
|
|
|
# Getting the WKB (in string form, to allow easy pickling of
|
|
# the adaptor) and the SRID from the geometry or raster.
|
|
if self.is_geometry:
|
|
self.ewkb = bytes(obj.ewkb)
|
|
self._adapter = Binary(self.ewkb)
|
|
else:
|
|
self.ewkb = to_pgraster(obj)
|
|
|
|
self.srid = obj.srid
|
|
self.geography = geography
|
|
|
|
def __conform__(self, proto):
|
|
# Does the given protocol conform to what Psycopg2 expects?
|
|
if proto == ISQLQuote:
|
|
return self
|
|
else:
|
|
raise Exception('Error implementing psycopg2 protocol. Is psycopg2 installed?')
|
|
|
|
def __eq__(self, other):
|
|
if not isinstance(other, PostGISAdapter):
|
|
return False
|
|
return (self.ewkb == other.ewkb) and (self.srid == other.srid)
|
|
|
|
def __hash__(self):
|
|
return hash((self.ewkb, self.srid))
|
|
|
|
def __str__(self):
|
|
return self.getquoted()
|
|
|
|
def prepare(self, conn):
|
|
"""
|
|
This method allows escaping the binary in the style required by the
|
|
server's `standard_conforming_string` setting.
|
|
"""
|
|
if self.is_geometry:
|
|
self._adapter.prepare(conn)
|
|
|
|
def getquoted(self):
|
|
"""
|
|
Return a properly quoted string for use in PostgreSQL/PostGIS.
|
|
"""
|
|
if self.is_geometry:
|
|
# Psycopg will figure out whether to use E'\\000' or '\000'.
|
|
return str('%s(%s)' % (
|
|
'ST_GeogFromWKB' if self.geography else 'ST_GeomFromEWKB',
|
|
self._adapter.getquoted().decode())
|
|
)
|
|
else:
|
|
# For rasters, add explicit type cast to WKB string.
|
|
return "'%s'::raster" % self.ewkb
|