NoReverseMatch at / when trying to add href in Django-CodePudding

I have a list of items and I am trying to add a link to the item's title to direct the user to the item's own page. However, I am getting Reverse for 'listing' with arguments '('',)' not found. 1 pattern(s) tried: ['listing/(?P<listing_id>[0-9] )\\Z'] error and I couldn't figure out what I did wrong.

The error is in line<h2><a href="{% url 'listing' listing.id %}">{{auction.title}}</a></h2> of index.html

urls.py:

from django.urls import path
from . import views

urlpatterns = [
    path("", views.index, name="index"),
    path("login", views.login_view, name="login"),
    path("logout", views.logout_view, name="logout"),
    path("register", views.register, name="register"),
    path("create", views.create_listing, name="create"),
    path("listing/<int:listing_id>", views.listing, name = "listing"),
]

views.py:

def listing(request,listing_id):
    listing = AuctionItem.objects.get(id = listing_id)
    return render(request, "auctions/listing.html",{
        "listing":listing
    })

index.html:

{% extends "auctions/layout.html" %}

{% block body %}
    <h2>Active Listings</h2>

    {% for auction in auctions %}
    <div class = "frame">
        <img src="{{auction.image}}" style= "width: 30vw;">
        <h2><a href="{% url 'listing' listing.id %}">{{auction.title}}</a></h2>
        <div id="text"><strong>Price:</strong> ${{auction.price}}</div>
        <div id="text"><strong>Description:</strong> {{auction.description}}</div>
        <div id="text"><strong>Category:</strong> {{auction.category}}</div><br>
        <div id="date">Created {{auction.date}}</div>
    </div>

        {% empty %}
        <li>No item.</li>
    {% endfor %}
{% endblock %}

CodePudding user response：

The object is named auction in the context when rendering, so:

<h2><a href="{% url 'listing' auction.id %}">{{auction.title}}</a></h2>

or perhaps better to use the .pk:

<h2><a href="{% url 'listing' auction.pk %}">{{auction.title}}</a></h2>