def register_user(request):
    if request.method == 'POST':
        form = UserCreationForm(request.POST)
        if form.is_valid():
            form.save()
            username = form.cleaned_data['username']
            password = form.cleaned_data['password1']
            return JsonResponse({'username': username, 'password': password})
        else:
            return JsonResponse({
                'error': 'Form not valid',
                'messages': form.error_messages,
                'cleaned_data': form.cleaned_data,
                'data': form.data,
                })

{"error": "Form not valid",
 "messages": {"password_mismatch": "The two password fields didn't match."},
 "cleaned_data": {"username": "test",
                  "password1": "qwe"},
 "data": {"csrfmiddlewaretoken": "long string:)",
          "username": "test",
          "password1": "qwe",
          "password2": "qwe"}}