Hi,
I am currently working on adding support for Oracle to GeoAlchemy and
Oracle has some methods [1] that (somehow) are only recognized when a
table alias is used. The function "aliased" [2] seemed to work
perfectly, but then I realized that the compiler extension for my
custom column is not executed anymore.
The compiler extension looks like this [3]:
[..]
class GeometryExtensionColumn(Column):
pass
@compiles(GeometryExtensionColumn)
def compile_column(element, compiler, **kw):
if kw.has_key("within_columns_clause") and
kw["within_columns_clause"] == True:
return compiler.process(functions.wkb(element))
return element.__str__()
[..]
And if I make a query using the original mapped class, it works as
expected:
s = session.query(Spot).get(1)
2010-05-10 11:49:19,957 INFO sqlalchemy.engine.base.Engine.0x...408c
SELECT SDO_UTIL.TO_WKBGEOMETRY(spots.spot_location) AS
spots_spot_location, spots.spot_id AS spots_spot_id, spots.spot_height
AS spots_spot_height
FROM spots
WHERE spots.spot_id = :param_1
2010-05-10 11:49:19,958 INFO sqlalchemy.engine.base.Engine.0x...408c
{'param_1': 1}
But when I create an alias and use this alias in a query,
"compile_column" is not called anymore and in this case
"SDO_UTIL.TO_WKBGEOMETRY" is not added to the query:
spot_alias = aliased(Spot)
s_alias = session.query(spot_alias).filter(spot_alias.spot_id ==
1).first()
2010-05-10 11:49:36,481 INFO sqlalchemy.engine.base.Engine.0x...408c
SELECT spots_1_spot_location, spots_1_spot_id, spots_1_spot_height
FROM (SELECT spots_1_spot_location, spots_1_spot_id,
spots_1_spot_height, ROWNUM AS ora_rn
FROM (SELECT spots_1.spot_location AS spots_1_spot_location,
spots_1.spot_id AS spots_1_spot_id, spots_1.spot_height AS
spots_1_spot_height
FROM spots spots_1
WHERE spots_1.spot_id = :spot_id_1)
WHERE ROWNUM <= :ROWNUM_1)
WHERE ora_rn > :ora_rn_1
What is going wrong?
Thanks,
Tobias
[1]:
http://download.oracle.com/docs/cd/E11882_01/appdev.112/e11830/sdo_objrelschema.htm#insertedID3
[2]: http://www.sqlalchemy.org/docs/ormtutorial.html#using-aliases
[3]:
http://bitbucket.org/geoalchemy/geoalchemy/src/c0bfcd46cb3a/geoalchemy/geometry.py#cl-121
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