On Wednesday, August 27, 2014 4:58:50 PM UTC-7, Michael Bayer wrote: > > > On Aug 27, 2014, at 6:17 PM, Gerald Thibault <diesel...@gmail.com > <javascript:>> wrote: > > > I have a pretty simple goal, so simple I probably don't even need > example code. > > > > I have 2 classes, and I want to pull the identity key from an instance > of one class, and use the values to create an instance of the second, > without requiring (or introspecting) things like the PK names, FK names > linking them, etc. Something like: > > > > instance1 = Class1() > > cls, vals = identity_key(instance=instance1) > > instance2 = Class2.from_identity_key(vals) # that method doesn't exist > > > > I am trying to do this without requiring any of the PK column names or > FK info linking the 2 tables together (they are a 1-to-1 relationship). > given only an instance of Class1 and the class "Class2", I want to create > the instance of Class2. > > > > Is this possible? Is there a way to "reverse" identity_key, so instead > of instance -> (cls, vals) I could do (cls, vals) -> instance? > > OK well how to the primary key attributes of Class1 and Class2 relate? > If Class1’s primary key columns are “a”, “b”, and Class2’s primary key > columns are, “id”, how is that mapping done? are we assuming same number > of columns in the PK of both, in the same order, or same names, or what? > > The pks are named differently in every case, which is why i was looking for a way that didn't involve use of keys at all. For every case, the length of the pks are the same, and the columns comprising the key are in the same order.
The mapping is done by a standard relationship, but I was thinking I wouldn't need the mapping at all if i am just pulling and pushing a pk value. The name of the relationship is different in every case. -- 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 sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
