#24048: only() doesn't override fields included in defer() as documented
-------------------------------------+-------------------------------------
     Reporter:  wearp                |                    Owner:  nobody
         Type:  Bug                  |                   Status:  new
    Component:  Database layer       |                  Version:  master
  (models, ORM)                      |
     Severity:  Normal               |               Resolution:
     Keywords:  defer, only,         |             Triage Stage:  Accepted
  QuerySet, DeferredAttribute        |
    Has patch:  0                    |      Needs documentation:  0
  Needs tests:  0                    |  Patch needs improvement:  0
Easy pickings:  0                    |                    UI/UX:  0
-------------------------------------+-------------------------------------

Comment (by wearp):

 Replying to [comment:1 timgraham]:
 > I checked back to 29050ef999e1931efb6c62471c7e07d2ea5e96ea where
 `defer()` was added and this assertion in `tests/defer` (or its equivalent
 in the original doc test) fails,
 `self.assert_delayed(qs.defer("name").only("value", "name")[0], 1)` as
 "name" is indeed deferred despite its inclusion in `only()`. It seems
 expected to me that `only()` would override `defer()` so we should see
 about making that change, but if we can't due to backwards compatibility
 or implementation, we should definitely correct the docs.

 Looking at the comment for `only()` it says,
        `Only the fields passed into this method and that are not already
 specified as deferred are loaded immediately when the queryset is
 evaluated.`

 This would mean that the method behaves as intended and the documentation
 is incorrect. `add_immediate_loading()` (which is called by `only()`) also
 behaves in the same way, not overriding  deferred fields passed to it.

--
Ticket URL: <https://code.djangoproject.com/ticket/24048#comment:3>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.

-- 
You received this message because you are subscribed to the Google Groups 
"Django updates" 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].
To view this discussion on the web visit 
https://groups.google.com/d/msgid/django-updates/063.771a2b8bb0e9dfabba43d70ee5dc94a7%40djangoproject.com.
For more options, visit https://groups.google.com/d/optout.

Reply via email to