Handling Form Submissions with Post-Redirect-Get Pattern in Django

The issue you're experiencing is a common one in web development. When you submit a form and then refresh the page, the browser tries to resubmit the form data. This is because you're using a direct render after POST submission rather than following the Post-Redirect-Get (PRG) pattern.

The Problem with Your Current Approach

Your current implementation renders the template directly after processing the form, which means the POST request remains "active" in the browser's history. When refreshing, the browser will attempt to resubmit this POST request.

Solution: Using Django Sessions

The best approach is to use Django's session framework to store the result temporarily and then redirect to a GET request:

PYTHONCopied
def abc(request):
    if request.method == "POST":
        stop = request.POST["stop"]
        data_res = rnd.randrange(int(stop))
        
        # Store the result in the session
        request.session['result'] = data_res
        
        # Redirect to the same page (as a GET request)
        return redirect('abc')
    
    # For GET requests, retrieve the result from session if it exists
    result = request.session.get('result', None)
    
    # Optionally clear the result from session after retrieving it
    if 'result' in request.session:
        del request.session['result']
    
    return render(request, 'abc/mypage.html', {'result': result})

Why Your Redirect Approach Didn't Work

The error you received was because the redirect() function doesn't accept a context dictionary as its second argument. The correct usage for redirect() is:

PYTHONCopied
redirect('view_name')  # Using the name from urls.py
# or
redirect('/some/url/')  # Using a URL path

Using Class-Based Views

Alternatively, you could implement this using Django's class-based views, which can make form handling more structured:

PYTHONCopied
from django.views import View
from django.shortcuts import render, redirect

class AbcView(View):
    template_name = 'abc/mypage.html'
    
    def get(self, request, *args, **kwargs):
        result = request.session.get('result', None)
        if 'result' in request.session:
            del request.session['result']
        return render(request, self.template_name, {'result': result})
    
    def post(self, request, *args, **kwargs):
        stop = request.POST.get("stop")
        data_res = rnd.randrange(int(stop))
        request.session['result'] = data_res
        return redirect('abc')

Then update your urls.py:

PYTHONCopied
path('abc', views.AbcView.as_view(), name='abc'),

This approach follows Django's recommended pattern for form handling, separating the GET and POST logic clearly while preventing form resubmission on page refresh.