ImageField not populate width/height attributes

[roman-rr]

Create an object with ImageField within REST API are not automatically populated values into width_field and height_field.
Create the same object from django admin - width and heights are properly passed.

I dig deeper issue and found following things.
Dimensions assigned in ImageFileDescriptor setter.
Setter __set__ from ImageFileDescriptor function executed only once, right after model execute .save() method.
When create object from django admin, this setter executed few times before .save() method.

Currently i solve this issue with hack:

class Photo(models.Model):
  photo = models.ImageField(
        height_field='photo_height',
        width_field='photo_width',
  )

  class Meta:
        ordering = ('-created_at',)

  def save(self, *args, **kwargs):
        # add additional setter call before save model to re-assign width/height into our fields
        self.photo = self.photo 
        return super(CommentPhotoRel, self).save(*args, **kwargs)

But i believe that there are some reasons, setter called only one time after save, rather than admin model creation, where setter called few times before save.

Any thoughts ?

Checklist

• This cannot be dealt with as a third party library. (We prefer new functionality to be in the form of third party libraries where possible.)
• I have reduced the issue to the simplest possible case.