Re: [patch] Updated Patch for fault-join-target-slot and update-objects-joins

I've been trying to use the join slots recently but have run into the
same 'it does not work the way you'd expect' problem.
I'd love to see this 'do the right thing'.  
It's either that or switch to doing this all 'by hand' and maintaining
my own instance <-> db mapping.

- Dominic


On Tue, 01 Nov 2005 09:14:42 -0800, "Drew Crampsie" <[email protected]>
said:
> Aleksandar Bakic wrote:
> >>>Attached is an updated version of my previous patch which also fixes the 
> >>>problems with update-objects-joins when using the :target-slot attribute.
> >>
> >>Thanks for the patch, Drew.
> >>
> >>I've applied it and released CLSQL 3.3.3 with your fix.
> > 
> > 
> > Hi,
> > 
> > What should happen if the target slot is not a join slot at all, but a regular
> > one? I am getting an error at this point in fault-join-target-slot:
> > 
> > 	 (tdbi (view-class-slot-db-info
> > 		(find ts (class-slots (find-class jc)) 
> > 		      :key #'slot-definition-name))) 
> > 	 (retrieval (gethash :retrieval tdbi)) ; tdbi is nil
> 
> What is it that you are trying to do? :target-slot is specifically for 
> many-to-many joins, and i can't see it making sense outside of them. it 
> would probably be trivial to simply return the sql-slot-value of the 
> :target-slot when it is not a join slot, but i can't see what value this 
> gains.
> 
> FWIW, although the patch corrects 'can't find class' issue, f-j-t-s 
> still doesn't work for my purposes as it doesn't fill in the primary 
> keys (when using :deferred, none of the instances actually come from the 
> database. when using :immediate (which i never use) the target class has 
> "real" instances, but the join-class (hosting the many-to-many) just 
> fills the joined keys, but does not get the actual rows from the 
> database. Both of these behaviors i find completely useless. A 'regular' 
> join slot returns 'real' instances that i can manipulate and 
> UPDATE-RECORDS-FROM-INSTACE, where a many-to-many returns these 'pseudo' 
> instances that do me no good at all.
> 
> I've modified my clsql f-j-t-s locally to use the following definition :
> 
> (defun fault-join-target-slot (class object slot-def)
>    (let* ((dbi (view-class-slot-db-info slot-def))
> 	 (ts (gethash :target-slot dbi))
> 	 (jc  (gethash :join-class dbi))
> 	 (foo (warn "~A ~A " (class-slots (find-class jc)) ts ))
> 	 (jc-view-table (view-table (find-class jc)))
> 	 (tdbi (view-class-slot-db-info
> 		(find ts (class-slots (find-class jc))
> 		      :key #'slot-definition-name)))
> 	 (retrieval (gethash :retrieval tdbi))
> 	 (tsc (gethash :join-class tdbi))
> 	 (ts-view-table (view-table (find-class tsc)))
> 	 (jq (join-qualifier class object slot-def))
> 	 (key (slot-value object (gethash :home-key dbi))))
> 
>      (when jq
>        (let ((res
> 		(find-all (list jc)
> 			  :inner-join (sql-expression :table ts-view-table)
> 			  :on (sql-operation
> 			       '==
> 			       (sql-expression
> 				:attribute (gethash :foreign-key tdbi)
> 				:table ts-view-table)
> 			       (sql-expression
> 				:attribute (gethash :home-key tdbi)
> 				:table jc-view-table))
> 			  :where jq
> 			  :result-types :auto
> 			  :database (view-database object))))
> 	   (mapcar #'(lambda (i)
> 		       (setf (slot-value (car i) 'view-database) (view-database object))
> 		       (cons (car
> 			      (select tsc
> 				      :where (sql-= (sql-slot-value tsc (gethash :foreign-key tdbi))
> 						    (slot-value (car i)  (gethash :home-key tdbi)))
> 				      :flatp t))
> 			     i))
> 		   res)))))
> 
> 
> This 'works', although it hits the database a lot. I'd rather do a join, 
> but clsql seems to offer no way of doing what i need to do (although my 
> clsql-internals-fu is quite possibly not up to the task). I'm still 
> hacking on this locally, but am using the above in production (with 
> great success i might add).
> 
> The behavior of f-j-t-s as i've patched it locally, to me, seems the be 
> the right-thing (tm). It is consistent with the rest of the OODML 
> interface, and removes a major source of confusion. I'm not sure what 
> behavior CommonSQL specified here, but the current behavior simply can't 
> be right.
> 
> Does anybody actually use :join-slot with the current behavior and can 
> justify keeping it that way? if not, i'd like to see my version, or 
> something that returns the same instances, in 3.3.4. I'll even volunteer 
> to update the documentation to remove any confusion about :target-slot :)
> 
> Thoughts?
> 
> drewc
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