How do I make Django show the "user already exists" message when someone tries to register with an existing username?

[Tom Tanner]

My `urls.py` has this:

url("^login_register/$", views.login_register, name="login_register"),

url("^register/$", views.register, name="register"),

`views.py` has this:

def login_register(request, template="pages/login_register.html"):
 '''
 Display registration and login forms
 '''
 registration_form= RegisterForm()
 return render(request, template, {"registration_form": registration_form})




def register(request):
 '''
 Process user registration
 '''
 if request.method=="POST":
  form= RegisterForm(request.POST)
  print form.is_valid()
  if form.is_valid():
   form.save()
   email= form.cleaned_data.get("email")
   raw_password= form.cleaned_data.get("password1")
   user= authenticate(username=email, password=raw_password)
   login(request, user)
   return redirect(home_slug())
 else:
  return redirect(reverse("login_register"))

`login_register.html` form HTML looks like this:

 <h2>Register</h2>
 <form method="post" action="{% url 'register' %}">
   {% csrf_token %}
   {{ registration_form.as_p }}
   <button type="submit">Register</button>
 </form>

When I fill out registration with an email that already exists, I get this error: `ValueError: The view theme.views.register didn't return an HttpResponse object. It returned None instead.`. That's because when `form.is_valid()` is False, there is no return value. What do I need to return so that the message on the Registration form states the email already exists?

[Matemática A3K]

`views.py` has this:

def login_register(request, template="pages/login_register.html"):
 '''
 Display registration and login forms
 '''
 registration_form= RegisterForm()
 return render(request, template, {"registration_form": registration_form})




def register(request):
 '''
 Process user registration
 '''
 if request.method=="POST":
  form= RegisterForm(request.POST)
  print form.is_valid()
  if form.is_valid():
   form.save()
   email= form.cleaned_data.get("email")
   raw_password= form.cleaned_data.get("password1")
   user= authenticate(username=email, password=raw_password)
   login(request, user)
   return redirect(home_slug())

 

 else:

 

-> Here you should redirect back to to login_register as fallback option, for this code, try removing this "else"

  return redirect(reverse("login_register"))

 

When I fill out registration with an email that already exists, I get this error: `ValueError: The view theme.views.register didn't return an HttpResponse object. It returned None instead.`. That's because when `form.is_valid()` is False, there is no return value. What do I need to return so that the message on the Registration form states the email already exists?

When you process the form in a different view, when you redirect you will loose the form content, a better approach is to process it in the same view, this way the errors will be shown "automatically":

https://stackoverflow.com/questions/14647723/django-forms-if-not-valid-show-form-with-error-message

Or handle the errors by yourself as shown here:

https://docs.djangoproject.com/en/1.11/intro/tutorial04/

:)

[Tom Tanner]

Thanks for replying. Looks like it'll be easier for me to combine these into one view.