CODEWITHSUNDEEP
pythondjango
Pike D.
Pike D.

Reputation: 691

Django Error: Reverse for 'blog_detail_url' with arguments '('',)' and keyword arguments '{}' not found. 1 pattern(s) tried: ['blog/(?P<id>\\d+)$']

On my blog, I am trying to create a URL pager system where I can link to the previous and next post by the ID of the Post model. Right now, every time I try to go to a blog web page I get this error: 

NoReverseMatch at /blog/2
Reverse for 'blog_detail_url' with arguments '('',)' and keyword arguments '{}' not found. 1 pattern(s) tried: ['blog/(?P<id>\\d+)$']

views.py:

def blog_detail(request, id):
    # post request from the url
    return render(request, "BlogHome/pages/post.html")
    post = Post.objects.get(id)

    # Next Post
    try:
        Next_Post_id = (post.id + 1)
        Next_Post = Post.objects.get(id=Next_Post_id)
    except ObjectDoesNotExist:
        Next_Post = None

    # Previous Post
    try:
        Previous_Post_id = (post.id - 1)
        Previous_Post = Post.objects.get(id=Previous_Post_id)
    except ObjectDoesNotExist:
        Previous_Post = None

    context = {'post': post, 'Next_Post': Next_Post, 'Previous_Post': Previous_Post}
    return render(request, "BlogHome/pages/post.html", context)

urls.py:

urlpatterns = [
url(r'^$', views.blog_list),
url(r'^(?P<id>\d+)$', views.blog_detail, name='blog_detail_url'),
]

post.html:

{% extends "BlogHome/includes/WELL.html" %}

{% block content %}
<script>
document.title = "Pike Dzurny | {{post.title}}"
</script>

<div class="container-fluid text-center">

    <center>

        <div class="well" id="WellPost">

            <div class="container-fluid">

                <h2 align="center" id="TitleText">{{post.title}}</h2>
                <h3 align="center" id="BodyText">{{ post.date|date:"m-d"}}</h3>
                <h3 align="left">{{ post.body|safe }}</h3>

                {% if Next_Post is defined and Previous_Post is defined %}
                <ul class="pager">
                    <li class="previous"><a href="{% url 'blog:blog_detail_url' Post.id %}"><span
                            aria-hidden="true">&larr;</span> Older</a></li>
                    <li class="next "><a href="{% url 'blog:blog_detail_url' Next_Post.id %}">Newer <span
                            aria-hidden="true">&rarr;</span></a></li>
                    <h1>1</h1>
                </ul>

                {% elif Next_Post is defined %}
                <ul class="pager">
                    <li class="previous disabled"><a href=""><span aria-hidden="true">&larr;</span> Older</a></li>
                    <li class="next"><a href="{% url 'blog:blog_detail_url' Next_Post.id %}">Newer <span aria-hidden="true">&rarr;</span></a>
                    </li>
                </ul>
                <h1>2</h1>

                {% elif Previous_Post is defined %}
                <ul class="pager">
                    <li class="previous"><a href="{% url 'blog:blog_detail_url' Post.id %}"><span aria-hidden="true">&larr;</span>
                        Older</a></li>
                    <li class="next disabled"><a href="">Newer <span aria-hidden="true">&rarr;</span></a></li>
                </ul>
                <h1>3</h1>

                {% else %}
                <ul class="pager">
                    <li class="previous disabled"><a href="{% url 'blog:blog_detail_url' Post.id %}"><span aria-hidden="true">&larr;</span> Older</a></li>
                    <li class="next disabled"><a href="{% url 'blog:blog_detail_url' Next_Post.id %}">Newer <span aria-hidden="true">&rarr;</span></a></li>
                </ul>
                <h1>4</h1>
                {% endif %}


            </div>
    </center>
</div>

{% endblock %}

The error is happening at line 22 in post.html (<li class="previous"><a href="{% url 'blog:blog_detail_url' Post.id %}"><span aria-hidden="true">&larr;</span> Older</a></li>). I'm guessing, I imporperly set up the jinja2 href?

Upvotes: 0

Views: 92

Answers (1)

denvaar
denvaar

Reputation: 2214

Change your links from 

"{% url 'blog:blog_detail_url' Next_Post.id %}"

to

"{% url 'blog:blog_detail_url' id=Next_Post.id %}"

Notice the id=. Your url pattern specifies id as a url kwarg.

Also, as a rule of thumb, you should not name your variables with upper-case letters. In Python, it's standard to use lower-case variable names, and then have upper case names for classes. When this is done consistently, it helps make your code more readable.

EDIT

This also seems a little fishy to me: {% if Next_Post is defined and Previous_Post is defined %} what is defined ? I don't see it in the context or anywhere else. I would do this:

{% if next_post %}
    {# ... #}
{% endif %}

Upvotes: 1

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