Django upload image using page slud/id - django

Question

I'm trying to add the ability to upload an image to a post but having issues.
The image field is in its own model but uses a foreign key to show which post it relates to.
At the moment the upload button does not post the form but also how would I use the post page url/slug/id as the image foreign key.
Would i need to call it in the html post page?
views.py
def designUpload(request):
if request.method == 'POST':
form = ImageForm(request.POST, request.FILES)
if form.is_valid():
form.save()
return render(request, 'users/dashboard.html')
else:
form = ImageForm()
return render(request, 'users/dashboard.html', {
'form': form
})
**models.py**
class Designs(models.Model):
forbrief = models.ForeignKey(Brief, on_delete=CASCADE)
postedby = models.ForeignKey(User, on_delete=models.CASCADE, null=True)
design = models.ImageField(null=True, blank=True)
date = models.DateTimeField(auto_now=True, blank=True)
forms.py
class ImageForm(forms.ModelForm):
class Meta:
model = Designs
fields = ["design",]
HTML Form
<form method="POST" enctype="multipart/form-data">
{% csrf_token %}
<input type="image" name="mydesign">
<button type="submit">Upload</button>
</form>