Michael Bayer ha scritto:
>
> On Jan 29, 2007, at 11:30 AM, Manlio Perillo wrote:
>
>>
>> The problem is that sometimes (at random, but I'm not sure),
>> SQLAlchemy
>> wants to use the lazy loader for comments, when I do session.load
>> (Derived).
>>
>
> thats sometimes due to an "eager degrade". eager loading will
> generally not issue its LEFT OUTER JOIN if constructing the query
> means it will loop back to the originating table in one query...it
> will stop at the point before it gets there. this kind of thing
> actually happens a lot. this can occur when using backrefs...if you
> have A and B with eager refs to each other, and you load an A with
> its B's, hitting the "A" collection on each "B" will incur as a lazy
> load...since the eager loader isnt going to eager load A->B->A->B->A...
>
Ok, I have noted this.
However this is not the case for me.
> but im not sure if thats whats happening here. maybe something up
> with load(), id guess if the instance is already in the session
> maybe.
This should not happen.
I load the object in a transaction (in a thread pool, where I create a
new session and then destroy it).
After loading the object, I try to access to the comments attribute in a
function (in the main thread, in this case).
This happens in a web application, in a POST command.
The full sequence is:
POST /id
1) load object by id {separate thread, transaction with session}
2) access the object attributes (I need this for validation)
{main thread}
3) validate the POST data {main thread}
4) update the object {separate thread, transaction with session}
The problem is in 2)
> it would help if you could show me more fully what youre doing.
>
Now I'm tring to hit the exception, but all works fine.
Thanks and regards Manlio Perillo
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