Django: Adding 2 variables and getting a response on the same page - django

Question

Any help would be greatly appreciated
index.html
{% extends 'base.html' %}
{% block content %}
<div>
<h1>Welcome Home</h1>
<form action="{% url 'calc:home' %}" method="GET">
<!-- {% csrf_token %} -->
Enter 1st Number : <input type="text" name="num1"><br><br>
Enter 2nd Number : <input type="text" name="num2"><br>
<input type="submit" name="" value="Add"><br><br>
</form>
Result of the game is : {{result}}
</div>
{% endblock %}
views.py
from django.shortcuts import render
from django.http import HttpResponse
def home_view(request):
if request.GET.get('num1'):
val1 = int(request.GET.get("num1"))
val2 = int(request.GET.get("num2"))
res = val1 + val2
return render(request, 'calc/index.html',{'result':res})
urls.py
from django.urls import path
from . import views
app_name = 'calc'
urlpatterns = [
path('', views.home_view, name='home'),
]
i get this error when running the server: UnboundLocalError: local variable 'res' referenced before assignment

Answer 1

I hope this will help. Basically you are using a variable outside of it's scope. you defined res in "if" block but called outside "if" though it was not present in that scope.So you should first assign a default value.
def home_view(request):
res=0
if request.GET.get('num1'):
val1 = int(request.GET.get("num1"))
val2 = int(request.GET.get("num2"))
res = val1 + val2
return render(request, 'calc/index.html',{'result':res})