Yes I know the question was a bit vague, but i couldn't think of a simple way to show some code. A test case would probably require some major surgery; I'll consider it though.
It is possible that the second instance is associated with a different session, i'd have to check. What actually happens if you add the same instance to a second session? CL On Mon, Sep 2, 2013 at 8:23 PM, Simon King <[email protected]> wrote: > Without knowing your application it's very difficult to know... > > Is there any chance that the second object is already associated with a > different session? Perhaps from a different thread, or retrieved from a > cache or something similar? > > Producing a standalone test script would help in diagnosing the problem. > > Simon > > > On 2 Sep 2013, at 18:56, Lars van Gemerden <[email protected]> wrote: > > > Well, from the message yes, but i am not setting any primary keys > manually, so where could the second instance come from? > > > > CL > > > > ==================================== > > Lars van Gemerden > > [email protected] > > +31 6 26 88 55 39 > > ==================================== > > > > On 2 sep. 2013, at 17:39, Simon King <[email protected]> wrote: > > > >> On Mon, Sep 2, 2013 at 4:01 PM, lars van gemerden <[email protected]> > wrote: > >>> Hi all, > >>> > >>> I have a one-to-one and many-to-one relationship (with an association > table > >>> in the middle; Report.author-assoctable-Person.reports; why the table > in the > >>> middle, you might ask, well it's a long story) and i am setting the > author > >>> on a specific Report twice to the same value. This gives the following > >>> error: > >>> > >>> InvalidRequestError: Can't attach instance <person at > 0x36a9350>; > >>> another instance with key (<class 'models.data.classes.person'>, (2,)) > is > >>> already present in this session. > >>> > >>> The first time i set the author, it works and if i change the author it > >>> works as well. > >>> > >>> This seems i little strange to me, why not be able to set the > attribute to > >>> the same value twice? > >>> > >>> Otherwise i have to check whether the new and old values are equal > (which > >>> through the peculiarties of my code is somewhat wastefull) > >>> > >> > >> I think the message is actually telling you that you have 2 different > >> instances of your "person" class with the same primary key. SQLAlchemy > >> uses an identity map to ensure that a particular row in the database > >> is only identified by a single instance within a particular session. > >> If you violate that assumption (eg. by loading one instance of > >> "person" from the database, then creating another instance and setting > >> its primary key), you will get errors like this. > >> > >> Does that sound plausible? > >> > >> Simon > >> > >> -- > >> You received this message because you are subscribed to a topic in the > Google Groups "sqlalchemy" group. > >> To unsubscribe from this topic, visit > https://groups.google.com/d/topic/sqlalchemy/bkm3-nB6d1o/unsubscribe. > >> To unsubscribe from this group and all its topics, send an email to > [email protected]. > >> To post to this group, send email to [email protected]. > >> Visit this group at http://groups.google.com/group/sqlalchemy. > >> For more options, visit https://groups.google.com/groups/opt_out. > > > > -- > > You received this message because you are subscribed to the Google > Groups "sqlalchemy" group. > > To unsubscribe from this group and stop receiving emails from it, send > an email to [email protected]. > > To post to this group, send email to [email protected]. > > Visit this group at http://groups.google.com/group/sqlalchemy. > > For more options, visit https://groups.google.com/groups/opt_out. > > -- > You received this message because you are subscribed to a topic in the > Google Groups "sqlalchemy" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/sqlalchemy/bkm3-nB6d1o/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/sqlalchemy. > For more options, visit https://groups.google.com/groups/opt_out. > -- ==================================== Lars van Gemerden [email protected] +31 6 26 88 55 39 ==================================== -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/groups/opt_out.
