[sqlalchemy] Re: Mapper bug involving select with labeled foreign key target and clause default?
Thanks for the response Mike... comments below. On Oct 28, 12:52 am, Michael Bayer [EMAIL PROTECTED] wrote: On Oct 27, 2007, at 8:33 PM, Brian Beck wrote: without trying it yet the first thing that seems wrong is that your select has no join condition between a_table and b_table (nor are you using a join(), which would figure it out for you based on foreign keys, so your foreign key doesn't impact the equation much here on the select side). the select will return the cartesian product between a and b which is definitely not what you want. Doesn't matter -- same thing happens with or without the join condition. (The cartesian product was intentional.) the actual error seems that the b_id column is tripping off a refresh of the instance's row, but when it issues your select(), its still not getting back what it wants. since the mapper seems confused by the primary key of the select (which is likely because you have a_id represented twice), you might want to look into setting up your 'the_id_of_a' property at the mapper level as a synonym() or column_property() attribute. I dont see what good it does embedded into that select(). or, try explicitly setting the mapper's primary_key attribute to the desired columns from your select(). Pretend the Select is more complicated and needs to reference both IDs (which may have come from subqueries) -- in this case any mapper features (like synonym) don't help, the Select needs to exist first! Isn't it an error that b_id trips off a refresh? The correct values are inserted and should be available in last_inserted_ids for the mapper to populate instance with... --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: Mapper bug involving select with labeled foreign key target and clause default?
On Oct 28, 2007, at 4:32 PM, Brian Beck wrote:
Pretend the Select is more complicated and needs to reference both IDs
(which may have come from subqueries) -- in this case any mapper
features (like synonym) don't help, the Select needs to exist first!
the select can reference whatever columns it wishes in its WHERE
clause, ORDER BY clause, whereever, *without* them being in the
columns clause...your columns clause need not reference any columns
whatsoever and it can still locate the correct rows. so you should
be putting only unique columns in the columns clause of your
SELECT.or, if youd like to tell your mapper about both columns
being the same, set up the mapping like this:
ab_mapper = mapper(AB, s, properties={
'id':[s.c.a_id, s.c.the_id_of_a]
})
then the class has a single 'id' attribute mapped to both columns.
Isn't it an error that b_id trips off a refresh? The correct values
are inserted and should be available in last_inserted_ids for the
mapper to populate instance with...
this is a slight issue in that its seeing the inline SQL as a
postfetch trigger when its not, so that is fixed in r3679.
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[sqlalchemy] Re: Mapper bug involving select with labeled foreign key target and clause default?
On Oct 27, 2007, at 8:33 PM, Brian Beck wrote: Sorry for the confusing subject. If I map against a select in which one of the tables has a foreign key whose default value is set to a clause involving another table's column (also in the select), and that column is labeled, the correct values are inserted, but an exception is raised when accessing the foreign key attribute on the instance (the instance is in an invalid state). without trying it yet the first thing that seems wrong is that your select has no join condition between a_table and b_table (nor are you using a join(), which would figure it out for you based on foreign keys, so your foreign key doesn't impact the equation much here on the select side). the select will return the cartesian product between a and b which is definitely not what you want. the actual error seems that the b_id column is tripping off a refresh of the instance's row, but when it issues your select(), its still not getting back what it wants. since the mapper seems confused by the primary key of the select (which is likely because you have a_id represented twice), you might want to look into setting up your 'the_id_of_a' property at the mapper level as a synonym() or column_property() attribute. I dont see what good it does embedded into that select(). or, try explicitly setting the mapper's primary_key attribute to the desired columns from your select(). just some things to try. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
