Hi!
I considered making `returning: bool` a flag that we are returning data.
That would make it `Foo.objects.update(x=1, y=2, returning=True)` and
avoid some footguns. Or even a new function (`update_returning`?) because I
have mixed feelings about different return types based on parameters.
Returning fields other than ones updated is a valid case IMO: we can update
some records and return the PKs of updated records for logging instead of
having just the number of rows updated. Something like`.values_list('pk',
flat=True)` is useful then.
On Sat, Oct 7, 2023 at 6:46 PM Tom Carrick <t...@carrick.eu> wrote:
> Hi Aivars,
>
> Since we spoke yesterday I've been thinking about this...
>
> I don't really see the value in returning a QuerySet. There are only a
> limited number of options that make sense at this point, and even those are
> tough to justify. Like what would happen if you do `Foo.objects.update(x=1,
> returning=["x"]).values("y")`?
>
> I do see value in returning the model instances, though I feel there is a
> potential footgun here where you can update a field, but not return it, so
> you'd get the old value in the instance. Something like:
>
> `Foo.objects.update(x=1, y=2, returning=["x"])`
>
> Now you have updated y, but the model instance that gets returned still
> has the old value. Maybe this is fine with a warning in the docs.
>
> I think regardless of what we do here, we should stick with the proposed
> and roughly agreed upon API of having an extra argument to `update()`
> rather than creating a new QuerySet method.
>
> Cheers,
> Tom
>
>
> On Tue, 3 Oct 2023 at 23:38, Plamedi klj <plamedikl...@gmail.com> wrote:
>
>> Bien
>>
>> Le lun. 25 sept. 2023 à 17:44, Aivars Kalvāns <aivars.kalv...@gmail.com>
>> a écrit :
>>
>>> Hi!
>>>
>>> I want to implement these changes and I have a PR in the ticket
>>> https://code.djangoproject.com/ticket/32406
>>> At the moment I have a new `update_returning` method but I can easily
>>> replace it with ` (updates=None, *, returning:bool=None, **kwargs)` if you
>>> decide to add functionality to the existing method instead. I did a search
>>> on github and found only a single project with `returning` as model field.
>>> However the returned value in my implementation is a `QuerySet` and I
>>> can do `.get()`, `.only()`, `.defer()` and `.values()` or `.values_list()`
>>> on that. Mainly because my use case is updating and refreshing the model in
>>> a single database operation. The ticket has more examples. What do you
>>> think, do you see any issues with this approach?
>>>
>>> trešdiena, 2021. gada 12. maijs 15:18:50 UTC+3 Tom Carrick rakstīja:
>>>
>>>> Apologies, I had totally forgotten about this, but I'm still interested
>>>> in working on it, but still not sure about a few things.
>>>>
>>>> I've been thinking about the return value a bit. I can foresee cases
>>>> where you wouldn't want the id returned. You might want the user to update
>>>> something by slug, username, or some other identifier without revealing the
>>>> IDs. Of course the user could reformat the return value however they like,
>>>> but I don't see a reason to ask for something that isn't necessary.
>>>>
>>>> So I think a list of some kind of object (namedtuple or dict probably)
>>>> makes the most sense to me. As for also adding the count, I am not sure.
>>>> The return value would then be e.g. (1, [<data>]). I'm guessing this count
>>>> would remain as the number of matched rows, rather than the updated ones -
>>>> I am not sure if returning only gives back rows that were modified or not,
>>>> the Postgres docs are at least unclear on this. If they're always going to
>>>> be the same, I'm not sure there is much reason for returning the count when
>>>> len(return_value) will do.
>>>>
>>>> I'm also not really sure on the data structure though. Namedtuples make
>>>> the most sense to me but a dict might be useful for those wanting to shove
>>>> this directly into JsonResponse, without needing _asdict(), for example.
>>>>
>>>> Cheers,
>>>> Tom
>>>>
>>>> On Wed, 27 Jan 2021 at 10:45, Florian Apolloner <f.apo...@gmail.com>
>>>> wrote:
>>>>
>>>>> Hi Simon,
>>>>>
>>>>> On Wednesday, January 27, 2021 at 5:54:42 AM UTC+1 charettes wrote:
>>>>>
>>>>>> I think that's the best option here if we want to elegantly add
>>>>>> support for this feature while maintaining backward compability.
>>>>>> Something
>>>>>> along the lines of ...
>>>>>>
>>>>>
>>>>> That is certainly an interesting approach. It kinda breaks the "there
>>>>> should be one way of doing things" rule, but…
>>>>>
>>>>> The usage of `returning` bring another set of questions though. Since
>>>>>> UPDATE are not ordered RETURNING data has little value without the
>>>>>> primary
>>>>>> key associated with the updated rows. Maybe the return value of
>>>>>> `returning=[f1, ..., fn]` should be a dict mapping the primary key to
>>>>>> list
>>>>>> of returning values.
>>>>>>
>>>>>
>>>>> I am not sure I like that. For things where you update just one row
>>>>> and want to know the new values the primary key doesn't make much sense.
>>>>> Granted for multiple rows it would maybe easier to have it automatically
>>>>> keyed by the pk, but returning something always (the pk) without having an
>>>>> option to disable it seems kinda wrong to me. Not sure what the best
>>>>> option would be.
>>>>>
>>>>> Cheers,
>>>>> Florian
>>>>>
>>>>> --
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