Make Model.save() arguments keyword-only

[Jacob Walls]

Following this forum ​discussion, I suggest making Model.save() accept keyword arguments only (following a deprecation period, of course).

For users who need to patch update_fields in an overridden save(), it would be much simpler to only have to drill into **kwargs and not also drill into (and check the length of) *args first.

Implementing this ticket would alleviate a small part of a current inconsistency in the advice for overridding save(). In one portion, the implementer is advised to pass through both *args and **kwargs:

It's also important that you pass through the arguments that can be
passed to the model method -- that's what the ``*args, **kwargs`` bit
does. Django will, from time to time, extend the capabilities of
built-in model methods, adding new arguments. If you use ``*args,
**kwargs`` in your method definitions, you are guaranteed that your
code will automatically support those arguments when they are added.

Then, an example tailored to passing through update_fields, passes through *no* variadic arguments:

        def save(
            self, force_insert=False, force_update=False, using=None, update_fields=None
        ):

We could make the situation better by taking away swallowed *args as a vector for bugs.

[Mariusz Felisiak]

Sounds reasonable.

[Aryan Gholizadeh Mojaveri]

May we create a PR for this now?

[Jacob Walls]

I haven't started, so if you'd like to assign the ticket to yourself, that's fine with me. (Be sure to follow the "Deprecating a feature" instructions and update the two documentation examples I mentioned above.)

[Adam Johnson]

Nice one. If this ticket goes well, it might serve as a template for making some other functions keyword-only, such as models.Field.__init__ (except the first two args, verbose_name and name).

[Mariusz Felisiak]

Replying to Adam Johnson:

Nice one. If this ticket goes well, it might serve as a template for making some other functions keyword-only, such as models.Field.__init__ (except the first two args, verbose_name and name).

We already have "templates" for such deprecations e.g. ad18a0102cc2968914232814c6554763f15abbe3 or b8738aea14446b267a47087b52b38a98b440a6aa.

[Salvo Polizzi]

PR: ​https://github.com/django/django/pull/17667

[Salvo Polizzi]

I'm sorry but some tests do not work, so I temporarily closed PR. I will fix them

[Salvo Polizzi]

Replying to Salvo Polizzi:

I'm sorry but some tests do not work, so I temporarily closed PR. I will fix them

[Mariusz Felisiak <felisiak.mariusz@…>]

In 3915d4c:

Fixed #35060 -- Deprecated passing positional arguments to Model.save()/asave().

[GitHub <noreply@…>]

In 28522c3:

Fixed #35554, Refs #35060 -- Corrected deprecated *args parsing in Model.save()/asave().

The transitional logic added to deprecate the usage of *args for
Model.save()/asave() introduced two issues that this branch fixes:

• Passing extra positional arguments no longer raised TypeError.
• Passing a positional but empty update_fields would save all fields.

Co-authored-by: Natalia <124304+nessita@…>

[Natalia <124304+nessita@…>]

In 38717291:

[5.1.x] Fixed #35554, Refs #35060 -- Corrected deprecated *args parsing in Model.save()/asave().

The transitional logic added to deprecate the usage of *args for
Model.save()/asave() introduced two issues that this branch fixes:

• Passing extra positional arguments no longer raised TypeError.
• Passing a positional but empty update_fields would save all fields.

Co-authored-by: Natalia <124304+nessita@…>

Backport of 28522c3c8d5eb581347aececc3ac61c134528114 from main.

[nessita <124304+nessita@…>]

In 52ed2b64:

Refs #35060 -- Adjusted deprecation warning stacklevel in Model.save()/asave().

[Natalia <124304+nessita@…>]

In c87007ab:

[5.1.x] Refs #35060 -- Adjusted deprecation warning stacklevel in Model.save()/asave().

Backport of 52ed2b645e1dd8c9a874cfd21c4c9f2500032626 from main.

[Sarah Boyce <42296566+sarahboyce@…>]

In 38c20651:

Refs #35060 -- Fixed the update to update_fields in overridden save() method docs.

Regression in 3915d4c70d0d7673abe675525b58117a5099afd3.

[Sarah Boyce <42296566+sarahboyce@…>]

In bf45f067:

[5.1.x] Refs #35060 -- Fixed the update to update_fields in overridden save() method docs.

Regression in 3915d4c70d0d7673abe675525b58117a5099afd3.

Backport of 38c206515494cb28c48f77c10145a8aa9a172629 from main.