diff options
Diffstat (limited to 'examples/postgis/postgis.py')
| -rw-r--r-- | examples/postgis/postgis.py | 31 |
1 files changed, 13 insertions, 18 deletions
diff --git a/examples/postgis/postgis.py b/examples/postgis/postgis.py index 1239d66a4..77fcacba1 100644 --- a/examples/postgis/postgis.py +++ b/examples/postgis/postgis.py @@ -38,7 +38,6 @@ class TextualGisElement(GisElement, expression.Function): """ def __init__(self, desc, srid=-1): - assert isinstance(desc, basestring) self.desc = desc expression.Function.__init__(self, "ST_GeomFromText", desc, srid) @@ -63,21 +62,30 @@ class Geometry(UserDefinedType): # override the __eq__() operator def __eq__(self, other): - return self.op('~=')(_to_postgis(other)) + return self.op('~=')(other) # add a custom operator def intersects(self, other): - return self.op('&&')(_to_postgis(other)) + return self.op('&&')(other) # any number of GIS operators can be overridden/added here # using the techniques above. + def _coerce_compared_value(self, op, value): + return self + def get_col_spec(self): return self.name + def bind_expression(self, bindvalue): + return TextualGisElement(bindvalue) + + def column_expression(self, col): + return func.ST_AsText(col, type_=self) + def bind_processor(self, dialect): def process(value): - if value is not None: + if isinstance(value, GisElement): return value.desc else: return value @@ -165,8 +173,6 @@ def setup_ddl_events(): table.columns = table.info.pop('_saved_columns') setup_ddl_events() -# ORM integration - def _to_postgis(value): """Interpret a value as a GIS-compatible construct. @@ -188,17 +194,6 @@ def _to_postgis(value): else: raise Exception("Invalid type") -# without importing "orm", the "attribute_instrument" -# event isn't even set up. -from sqlalchemy import orm - -@event.listens_for(type, "attribute_instrument") -def attribute_instrument(cls, key, inst): - type_ = getattr(inst, "type", None) - if isinstance(type_, Geometry): - @event.listens_for(inst, "set", retval=True) - def set_value(state, value, oldvalue, initiator): - return _to_postgis(value) # illustrate usage @@ -245,7 +240,7 @@ if __name__ == '__main__': session.commit() # after flush and/or commit, all the TextualGisElements become PersistentGisElements. - assert str(r.road_geom) == "01020000000200000000000000B832084100000000E813104100000000283208410000000088601041" + assert str(r.road_geom) == "LINESTRING(198231 263418,198213 268322)" r1 = session.query(Road).filter(Road.road_name=='Graeme Ave').one() |