fix: update pk field only raises unfriendly error

[waketzheng]

Description

Close #1870

Motivation and Context

Explicit raises OptionalError when executing await model.save(update_fields=['id'])

How Has This Been Tested?

make ci

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added the changelog accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[codspeed-hq]

CodSpeed Performance Report

Merging #1873 will not alter performance

_{Comparing waketzheng:update-pk-field-only (981d835) with develop (4e47cff)}

Summary

✅ 16 untouched benchmarks

[coveralls]

Pull Request Test Coverage Report for Build 13179624319

Details

• 5 of 5 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.002%) to 89.236%

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Totals
Change from base Build 13160076672:	0.002%
Covered Lines:	6491
Relevant Lines:	7090

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💛 - Coveralls

[henadzit]

@waketzheng I added benchmarks for updates, let's merge them first so we have a baseline for performance and can be sure that this changes doesn't impact it significantly.

[henadzit]

Can you please rebase on top of the latest changes in develop?

[henadzit]

The current logic assumes that if no values and no expressions, then the user must have been passed pk as part of update_fields. That is a bit hard to follow. What do you think about the version below?

for field in update_fields or self.model._meta.fields_db_projection.keys():
  field_obj = self.model._meta.fields_map[field]
  if field_obj.pk:
    if update_fields:
      raise OperationalError(
                f"Can't update pk field, use `{self.model.__name__}.create` instead."
            )
    continue

[waketzheng]

I think we should allow .update_fields=['id', 'xxx'] as the Django do. And show warning to make sure user want to do that.