How to load a separate image into the model?

Question

Django

Good afternoon.
There is this form:

class Layout(forms.Form):
    img = forms.ImageField()
    comment = forms.CharField(required=False, widget=forms.Textarea)

It is displayed on the page and it can be filled. After filling the data AJAX'om sent to the server. Through new FormData.
On the server, the file is written to disk like this:

with open(os.path.join(settings.MEDIA_ROOT, 'mockup', request.FILES['img'].name), 'wb+') as file:
    for chunk in request.FILES['img'].chunks():
        file.write(chunk)

It seems to me that there should be a more elegant way, but I simply did not find another.
After that, the file name and full path to it are written to session.
After some time, you need to write this data to the database, to the model, which has a field:

mockup = models.ImageField('Макет', blank=True, null=True)

Here's what I do (I read it on some forum):

d_f = File(open(c._mockup['img']['url']))
new_order.mockup.save(c._mockup['img']['name'], d_f, save=True)

But nothing works. Question:
How to do it right?
UPD:
The bug has been fixed. I forgot to add open flags to the open
function Then, if possible, answer another question - how to make loading more elegant.