Django image upload

forms.py

from django import forms

from models import ArticleImage

class ArticleImageForm(forms.ModelForm):
	class Meta:
		model = ArticleImage
		fields = ('image', )

models.py

from django.db import models
from django.contrib.auth.models import User


class ArticleImage(models.Model):
	user = models.ForeignKey(User)
	image = models.ImageField(
		height_field="height",
		upload_to='articles/%Y/%m',
		width_field="width",
	)
	datetime = models.DateTimeField(auto_now_add=True)
	width = models.IntegerField(default=0, blank=True)
	height = models.IntegerField(default=0, blank=True)

	def __unicode__(self):
		return self.image.name

views.py

@login_required
def article_upload_image(request):
	response = {
		'error': '',
		'url': '',
		'image_id': '',
	}
	ai = ArticleImage()
	ai.user = request.user

	form = ArticleImageForm(request.POST, request.FILES, instance=ai)

	if form.is_valid():
		ai = form.save()
		response['url'] = '%s%s' % (settings.MEDIA_URL, ai.image.name)
		response['image_id'] = ai.id
	else:
		response['error'] = unicode(form.errors)

	return HttpResponse('%(error)s|%(url)s|%(image_id)s' % response)