Setting initial field value in generic form through URL parameter

Question

I'm struggling to set an initial value in a form instance based on the URL parameter in Django 3.0.

I have a Claim model:

# models.py

class Claim(models.Model):
    product = models.ForeignKey(Product, on_delete=models.CASCADE)
    text = models.TextField()
    date_added = models.DateTimeField(default=timezone.now)
    member = models.ForeignKey(User, on_delete=models.CASCADE)

I have a NewClaimForm based on ModelForm:

# forms.py

class NewClaimForm(forms.ModelForm):
    class Meta:
        model = Claim
        fields = ['product', 'text']

I have a NewClaimView based on CreateView:

# views.py

class NewClaimView(LoginRequiredMixin, CreateView):
    model = Claim
    form_class = NewClaimForm
    template_name = 'portal/new_claim.html'

    def form_valid(self, form):
        form.instance.member = self.request.user
        return super(NewClaimView, self).form_valid(form)

And using the following template fragment on the index page...

# index.html

    <div class="card-deck">
        {% for product in products %}
            <div class="card text-center">
                <div class="card-header">
                    <h5 class="card-title text-primary">{{ product }}</h5>
                </div>
                <div class="card-body">
                    <ol class="card-text text-left">
                        <li>Fill in the {{ product }} form</li>
                        <li>Attach your medical records</li>
                        <li>Get your claim reviewed within 48 hours</li>
                    </ol>
                    <a href="{% url 'portal:new_claim_product' product_id=product.id %}" class="btn btn-primary">Online Form</a>
                </div>
            </div>
        {% endfor %}
    </div>

...I pass the product_id parameter to the URL:

# urls.py

app_name = 'portal'
urlpatterns = [
    path('new_claim/<int:product_id>/', NewClaimView.as_view(), name='new_claim_product'),
]

And lastly, this is what my new_claim template looks like:

# new_claim.html

{% extends "portal/base.html" %}
{% load bootstrap4 %}

{% block content %}
    <p>Submit a new claim</p>

    <form action="{% url 'portal:new_claim' %}" method='post' class="form" enctype="multipart/form-data">
        {% csrf_token %}
        {% bootstrap_form form %}
        {% buttons %}
            <button name="submit">Submit claim</button>
        {% endbuttons %}
    </form>

{% endblock content %}

I would like to now use the product_id to set the initial value of the product field in the form instance according to product_id . How can I achieve this?

Answer 1

Figured out how to do this by modifying the get method for my class-based view:

# views.py

class NewClaimView(LoginRequiredMixin, CreateView):
    model = Claim
    form_class = NewClaimForm
    template_name = 'portal/new_claim.html'

    def get(self, request, product_id=None, *args, **kwargs):
        form = self.form_class(initial={'product': product_id})
        return render(request, self.template_name, {'form': form})

    def form_valid(self, form):
        form.instance.member = self.request.user
        return super(NewClaimView, self).form_valid(form)

Here's a link to the relevant documentation .

Is this an optimal way to solve this?

Do I need the *args and **kwargs in the modified get method? I'm not using them in my code but perhaps it would be useful to keep them there for other purposes in the future?