add update_fields to FieldFile.save when save=True

[do-rtk]

Code of Conduct

• I agree to follow Django's Code of Conduct

Feature Description

The current implementation of FieldFile.save (ref: https://github.com/django/django/blob/cf1a80fc2d19f359744a20bb6cb1f0a169ef506b/django/db/models/fields/files.py#L96-L105 ) automatically saves all fields when the save argument is True i.e. .save(..., save=True)

This new feature will add support for passing update_fields like one does in Model.save we'll then just forward them to the instance.save

Problem

Currently, it's not possible to limit the scope of which fields are saved when a FieldField.save is called with save=True.

As stated in the docs:

1. This may be desirable if you want to update just one or a few fields on an object.
2. There will be a slight performance benefit from preventing all of the model fields from being updated in the database.

Also, for us, in practice, lacking this worsens the situation when race conditions occur.

Request or proposal

proposal

Additional Details

First time contributor. Please feel free to point things out to me.

Implementation Suggestions

seems to me that a simple passthrough will be sufficient. However, there's a question of whether the field in question should always be included in the update_fields

[github-actions]

Thank you do-rtk for sharing your idea! We have a lot of them so please be patient. You can see the current queue here.

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Reaction Guide

• 👍 This is something I would use
• 👎 This is something that would cause problems for me or Django
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• 🎉 This is an easy win

[shangxiao]

Thanks for the suggestion 🎉 (just one thing though that is helpful for others when referencing the docs it's not a bad idea to link to the section referenced)

Just FYI for others because I think it's important to state the current workaround, this would be:

field_file.save(name, file, save=False)
field_file.instance.save(update_fields=[…])  # (provided this is an update)

[rixx]

After looking around the docs a bit (I can’t be the only one who gets confused with what’s where between the FieldFile docs, the FileField docs, and the “Managing files” topic docs that do not mentions model.file_field.save() at all btw), I think calling out the behaviour a bit more explicitly in the File.save() docs also wouldn’t go amiss in the meantime.

That is to say: the docs say that model.field.save(…, save=True) is the same as model.field.save(…, save=False); model.save(), but a quick mention like “Note that the File.save() method does not pass arguments like update_fields to the instance’s save() method`” might make people more aware that they may want to limit saving to the file field – I know it never occurred to me despite working with Django and user file uploads for an embarrassing number of years.

[LilyAcorn]

A docs change here seems like an easy win to me. I'm also open to passing through update_fields and any other keyword arguments that make sense.