app/django/contrib/gis/db/backend/postgis/adaptor.py
author Pawel Solyga <Pawel.Solyga@gmail.com>
Tue, 14 Oct 2008 16:00:59 +0000
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"""
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 This object provides quoting for GEOS geometries into PostgreSQL/PostGIS.
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"""
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from django.contrib.gis.db.backend.postgis.query import GEOM_FROM_WKB
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from psycopg2 import Binary
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from psycopg2.extensions import ISQLQuote
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class PostGISAdaptor(object):
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    def __init__(self, geom):
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        "Initializes on the geometry."
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        # Getting the WKB (in string form, to allow easy pickling of
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        # the adaptor) and the SRID from the geometry.
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        self.wkb = str(geom.wkb)
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        self.srid = geom.srid
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    def __conform__(self, proto):
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        # Does the given protocol conform to what Psycopg2 expects?
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        if proto == ISQLQuote:
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            return self
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        else:
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            raise Exception('Error implementing psycopg2 protocol. Is psycopg2 installed?')
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    def __eq__(self, other):
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        return (self.wkb == other.wkb) and (self.srid == other.srid)
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    def __str__(self):
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        return self.getquoted()
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    def getquoted(self):
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        "Returns a properly quoted string for use in PostgreSQL/PostGIS."
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        # Want to use WKB, so wrap with psycopg2 Binary() to quote properly.
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        return "%s(%s, %s)" % (GEOM_FROM_WKB, Binary(self.wkb), self.srid or -1)