从Django视图上传图像

from django.db import models
class Image(models.Model):
    advertisement = models.ForeignKey(\'Advertisement\')
    image = ImageWithThumbsField(upload_to=store_path, blank=True)

class Advertisement(models.Model):
    #some code here

class AdvertOne(Advertisement):
    #some code again

class AdvertTwo(Advertisement):
    #and again

from models import Advertisement
from django.forms import *

class AdvertisementForm(ModelForm):
    message = CharField(max_length=400, widget=Textarea)
    image = ImageField(required=False)

def upload_advertisement(request):
    if request.method == \"POST\":
        form =  AdvertisementForm(request.POST,request.FILES, prefix=\'advertisement\')
        if form.is_valid():
            form.save()
            return HttpResponseRedirect(\"/\")
    else:    
        form =  AdvertisementForm(prefix=\'advertisement\')

    return render_to_response(\'advertisementform.html\', {
        \'form\':form,
    }, context_instance=RequestContext(request))