Hello Mike.
Thanks for this fix, works fine now.
Jürgen
Michael Bayer wrote:
I just committed this change, and re-tested the
examples/polymorph/polymorph.py example against mysql for it:
Index: lib/sqlalchemy/orm/util.py
===================================================================
--- lib/sqlalchemy/orm/util.py (revision 1468)
+++ lib/sqlalchemy/orm/util.py (revision 1469)
@@ -24,7 +24,15 @@
def polymorphic_union(table_map, typecolname, aliasname='p_union'):
colnames = sets.Set()
colnamemaps = {}
- for table in table_map.values():
+
+ for key in table_map.keys():
+ table = table_map[key]
+
+ # mysql doesnt like selecting from a select; make it an alias
of the select
+ if isinstance(table, sql.Select):
+ table = table.alias()
+ table_map[key] = table
+
m = {}
for c in table.c:
colnames.add(c.name)
this does something roughly equivalent to changing the polymorph.py
example to say:
# create a union that represents both types of joins.
person_join = polymorphic_union(
{
'engineer':people.join(engineers),
'manager':people.join(managers),
'person':people.select(people.c.type=='person').alias('plain_people'),
}, None, 'pjoin')
I thought there must be something simple like this.
SA can definitely do to much :)
On May 17, 2006, at 2:30 AM, j.kartnaller wrote:
This is for the actual Schema branch (Sa 0.2 rev. 1468).
Using polymorphism as it is shown in the examples
creates a SQL query like this :
SELECT pjoin.info AS pjoin_info,
pjoin.parent_id AS pjoin_parent_id,
pjoin.type AS pjoin_type,
pjoin.id AS pjoin_id
FROM (
SELECT info.info AS info,
contained.parent_id AS parent_id,
contained.type AS type,
info.id AS id
FROM contained JOIN info ON contained.id = info.id
UNION ALL
SELECT NULL AS info,
parent_id,
type,
id
FROM (
SELECT contained.id AS id,
contained.parent_id AS parent_id,
contained.type AS type
FROM contained
WHERE contained.type = "contained"
)
) AS pjoin
ORDER BY pjoin.id
Everything works fine with SQLite.
With MySQL this produces :
SQLError: (OperationalError) (1248, 'Every derived table must have its
own alias')
Using an alias in the select of the UNION ALL solves the problem :
SELECT pjoin.info AS pjoin_info,
pjoin.parent_id AS pjoin_parent_id,
pjoin.type AS pjoin_type,
pjoin.id AS pjoin_id
FROM (
SELECT info.info AS info,
contained.parent_id AS parent_id,
contained.type AS type,
info.id AS id
FROM contained JOIN info ON contained.id = info.id
UNION ALL
SELECT NULL AS info,
pjoin_1.parent_id,
pjoin_1.type,
pjoin_1.id
FROM (
SELECT contained.id AS id,
contained.parent_id AS parent_id,
contained.type AS type
FROM contained
WHERE contained.type = "contained"
) as pjoin_1 <----------------------------
) AS pjoin
ORDER BY pjoin.id
Jürgen
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-------------------------------------------------------
Using Tomcat but need to do more? Need to support web services, security?
Get stuff done quickly with pre-integrated technology to make your job
easier
Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
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-------------------------------------------------------
Using Tomcat but need to do more? Need to support web services, security?
Get stuff done quickly with pre-integrated technology to make your job easier
Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
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