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.
