无法在django中进行简单计算

# views.py
from django.shortcuts import render

def calculate(request):
    if request.method == 'POST':
        num1 = int(request.POST['num1'])
        num2 = int(request.POST['num2'])
        result = num1 + num2
        return render(request, 'result.html', {'result': result})
    return render(request, 'calculate.html')

# urls.py
from django.urls import path
from . import views

urlpatterns = [
    path('calculate/', views.calculate, name='calculate'),
]

# calculate.html
<form method="post" action="{% url 'calculate' %}">
    {% csrf_token %}
    <input type="text" name="num1">
    <input type="text" name="num2">
    <button type="submit">Calculate</button>
</form>

# result.html
<p>Result: {{ result }}</p>