Passing query string to ModelForm hidden field - Django

Question

I want to pass a query string e.g., ?refcode='A1234' to a hidden field called inbound_referral_code in a ModelForm.

My model is as follows:

class User(models.Model):
   email = models.EmailField(max_length=255, blank=False, unique=True)
   inbound_referral_code = models.CharField(max_length=255)

My ModelForm is currently as follows:

class UserForm(forms.ModelForm):
   model = User
   fields = ['email', 'inbound_referral_code']
   widgets = {'inbound_referral_code': forms.HiddenInput()}

My View is:

def register(request):
   if request.method == 'POST':
      form = UserForm(request.POST)
      [...]
   else:
      form = UserForm()
      return render(request, 'register.html', {'form': form})

And my template is currently:

<form action="{% url 'register' %}" method="post">
   {% csrf_token %}
   {{ form.as_p }}
   <input type="submit" value="Submit"/>
</form>

Two questions:

How do I assign ?refcode parameter to inbound_referral_code field?
What happens if ?refcode isn't provided?

Is your problem that you don't know how to set the inbound_referral_code when rendering, or that you don't know how to read it after the post? — fiveclubs
– fiveclubs, Commented Oct 6, 2017 at 16:28
Actually I don't understand either of those! I will update question... — Rob
– Rob, Commented Oct 6, 2017 at 16:35

Rob · Accepted Answer · 2017-10-10 15:11:26Z

2

Combining the different answers, the following solution worked:

Set the "initial" value of the form parameter, and ensure the template renders with the bound form if validation fails. The correct view function is:

def register(request):
   if request.method == 'POST':
      form = UserForm(request.POST)
      if form.is_valid():
         return redirect([...])
   else:
      refcode = request.GET.get('refcode')
      form = UserForm(intial={'inbound_referral_code': refcode)

   return render(request, 'register.html', {'form': form})

Note that the bottom return render(...) needed to be moved so that it is also called with the form from the POST request if it contains validation errors...

answered Oct 10, 2017 at 15:11

Rob

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Comments

NS0 · Accepted Answer · 2017-10-06 17:00:06Z

1

To assign the refcode, you need to pass it into the form, so you pass in something other than request.POST that contains it, change it before

dict = request.POST.copy()
dict["inbound_referral_code"] = request.POST.get("refcode")
form = UserForm(dict)
# ...

or after validating:

if form.is_valid():
    form.cleaned_data["inbound_referral_code"] = request.POST.get("refcode")

If it isn't provided, you can check for that and pass a custom value, or set a default when defining the form/model.

To set it in the template, you can pass an initial value

else:
  form = UserForm(initial={"inbound_referral_code": "ref-value-here"})
  return render(request, 'register.html', {'form': form})

edited Oct 6, 2017 at 17:00

answered Oct 6, 2017 at 16:30

NS0

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3 Comments

Rob Over a year ago

Ok - I am currently doing that, however I have modified the first block of code to work on GET (not POST). However, by doing this, the template is already throwing up a "this field is required" error on the email field immediately...

NS0 Over a year ago

If you want the email to be optional, you can define it in your form and pass required=False

Rob Over a year ago

No the issue isn't the email being optional - it is definitely required. The issue is I need to pass refcode to the form on a GET request... Given the current implementation it results in validation errors being thrown before the user has even tried to enter any data...

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