Pass current product_id to a Model in Django

I'm trying to give django a try by developing a simple page where people can ask something about a product

This is my model, i can create products in the admin area, display the product page, and the form shows up with the fields email, and text.

class Product(models.Model):
    category = models.ForeignKey(Category)
    title = models.CharField(max_length=100)
    text = models.TextField()

class Question(models.Model):
    email = models.CharField(max_length=100)
    product = models.ForeignKey(Product, default=?, editable=False)
    date = models.DateTimeField(auto_now=True, editable=False)
    text = models.TextField()

class QuestionForm(ModelForm):
    class Meta:
        model = Question

But i don't know how to tell the model which product id the question has to be saved to.

This is my views.py

# other stuff here
def detail(request, product_id):
    p = get_object_or_404(Product, pk=product_id)
    f = QuestionForm()
    return render_to_response('products/detail.html', {'title' : p.title, 'productt': p, 'form' : f},
    context_instance = RequestContext(request))

def question(request, product_id):
    p = get_object_or_404(Product, pk=product_id)
    f = QuestionForm(request.POST)
    new_question = f.save()

    return HttpResponseRedirect(reverse('products.views.detail', args=(p.id,)))

And the URL

urlpatterns = patter开发者_运维问答ns('products.views',
    (r'^products/$', 'index'),
    (r'^products/(?P<product_id>\d+)/$', 'detail'),
    (r'^products/(?P<product_id>\d+)/question/$', 'question')
)

Righ now it works if i put a "1" in the default attribute for the product foreign key in the question model (where the question mark is), it saves the question to the product id 1. But i don't know what to do to make it save to the current product.

You can either:

Send product_id as form value

Make product foreign key in your form a hidden field and set it's value to primary key value of the product in detail view. This way you don't need a product_id in your question view URL and arguments since the ID will be passed with POST data. (see link for examples)

Id would use this option, since you'd have cleaner question URL and you could do more validation in your form on the product.

or

Send product_id through URL

Use reverse in your detail view to build the form action attribute or use url template tag to build the action attribute in form template. This way you need product_id in your question URL and arguments but you don't need product field in your QuestionForm. Then in question view simply get the product instance and set it as FK value on Question.

Example:

Using url template tag in products/detail.html:

<form action="{% url question product.pk %}" method="post">
 .... 
</form>

Or use reverse in detail view:

def detail(request, product_id):
    p = get_object_or_404(Product, pk=product_id)
    f = QuestionForm()
    return render_to_response('products/detail.html', {
        'title' : p.title, 
        'product': p, 
        'action': reverse("question", args=[p.pk,]),
        'form' : f},
    context_instance = RequestContext(request))

your template:

<form action="{{ action }}" method="post">
 .... 
</form>

Either way your question view would need a line added which actually sets product instance to Question attribute:

def question(request, product_id):
    ...
    new_question.product = p