Another question:
I've subclassed Query and overridden populate_existing() to always
perform a flush() something like this:
def populate_existing(self):
# This is extremely important since otherwise changes are lost for
queried objects!
self.session.flush()
return super(CachingQuery, self).populate_existing()
But when you said that sqla uses it as well, I realized I may be
breaking something when I need the orm to "use query._get() to refresh
an existing instance".
However, when I search the sqlalchemy code for "populate_existing()",
it seems you never invoke populate_existing() except in tests. Can I
safely assume sqla will never invoke query.populate_existing()?
If so, my mod is safe. If not, back to the drawing board...
On Oct 25, 2:58 pm, Kent <[email protected]> wrote:
> I'm glad it's there... I need it when doing a refresh where I need to
> keep the current objects (because I've written other things on the
> object that the orm doesn't know about, so I need to keep the original
> instance).
>
> Restating: it's there because its original intent was to deal with
> expiration of attributes, whereas now, there are better ways to
> accomplish expiration and so populate_existing()'s usefulness now is
> only really the fact that it reuses existing objects. Does that sound
> accurate?
>
> On 10/25/2011 2:39 PM, Michael Bayer wrote:
>
>
>
>
>
>
>
> > its used when we use query._get() to refresh an existing instance, and if i
> > take it out some tests fail, so its accomplishing something.
>
> > that said, those operations which use it could certainly set autoflush
> > distinctly, because if i were to use populate_existing() on in userspace
> > (which I don't, the feature was added for 0.1 users before we knew how to
> > expire things) I'd want it to autoflush first. But for now the change
> > would be backwards incompatible with some hypothetical app that is using it
> > and expects pending changes to be erased.
>
> > On Oct 25, 2011, at 2:18 PM, Kent wrote:
>
> >> Mike,
> >> What is the rationale for making populate_existing() skip the
> >> autoflush?
>
> >> Thanks,
> >> Kent
>
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