NoReverseMatch at / django python:Reverse for '*' not found. tried - django

Question

Reverse for 'details' with arguments '('',)' not found. 1 pattern(s) tried: ['details/(?P[.\-\w]+)$']
I am getting this error when I open the home page. All other pages seem to work.
urls.py
app_name = 'main'
urlpatterns = [
url(r'^$', views.home, name='home'),
url(r'ask-question/$', views.question, name='ask-question'),
url(r'^details/(?P<slug>[.\-\w]+)$', views.details, name='details'),
]
views.py for the home page
def home(request):
questions = Question.objects.all().order_by("-date")
numbers = Question.objects.all().count()
numbers2 = Answer.objects.all().count()
total_users = User.objects.all().count()
# counting answers on specific questions
results = Question.objects.annotate(num_answers=Count('answer')).order_by("-date")
# PAGINATION ===============================
page = request.GET.get('page', 1)
paginator = Paginator(results,10)
try:
results = paginator.page(page)
except PageNotAnInteger:
results = paginator.page(1)
except EmptyPage:
results = paginator.page(paginator.num_pages)
# end of counting
empty = []
for a in Answer.objects.all():
idd = a.id
question_id = (a.question_id)
empty.append(str(question_id))
repeatition = Counter(empty)
# i = 0
# trend_list = []
# for x in range(len(repeatition)):
# new = repeatition.most_common()[i][0]
# trend_list.append(new)
# i += 1
# if len(trend_list) != 0:
# trend = Question.objects.get(id=trend_list[0])
# else:
# trend = 'No Trending Category'
# getting the answers to all questions in the front page
# search the questions ============
query= request.GET.get("q")
if query:
short_list = Question.objects.all()
questions = short_list.filter(title__icontains=query)
resulted = questions.annotate(num_answers=Count('answer'))
counted = questions.count()
context1 = {
'questions': questions,
'query': query,
'counted': counted,
'resulted': resulted,
}
return render(request, 'main/search.html',context1)
context = {
'questions': questions,
'numbers': numbers,
'numbers2': numbers2,
'total_users': total_users,
# 'trend': trend,
'results': results,
}
return render(request, 'main/index.html', context)
index.html
{% extends 'main/base.html' %} {% block content %}
<div class="container">
{% for message in messages %}
<div class="alert alert-{{ message.tags }} alert-dismissible" role="alert">
<button type="button" class="close" data-dismiss="alert" aria-label="Close">
<span aria-hidden="true">×</span>
</button> {{ message }}
</div>
{% endfor %}
</div>
<!-- end of the message container -->
<!-- start of the actual questions -->
<div class="container-fluid">
<h1 class="text-left" id="brand"> Recently Added Questions</h1>
<div class="row">
<div class="col-md-8">
<div id="qtns">
{% for q in results %}
<a href="{% url 'main:details' q.slug %}" id="questions">
<h4 id="titleq">{{ q.title }}</h4>
</a>
<a href="{% url 'main:filter' q.category %}">
<p class="badge badge-info">{{ q.category }}</p>
</a>
<p id="titleq">{{ q.date |timesince }} ago. {{ q.user }}</p>
<div class="text-right">
<p>Answers: {{q.num_answers}}</p>
</div>
<hr> {% endfor %}
</div>
</div>
<div class="col-md-3">
<div id="qtns1">
<br> {% if not user.is_authenticated %}
Ask Question<br><br> {% else %}
Ask Quesiton<br><br> {% endif %}
<div class="qtns2">
<h1 id="titleq">Statistics</h1>
<p>Questions asked: {{numbers}} </p>
<p>Answers: {{ numbers2 }}</p>
<p>Total Users: {{ total_users }}</p>
</div> <br>
<div class="qtns2">
Most answered:
<a href="{% url 'main:details' trend.slug %}" style="text-decoration:none;">
<p>{{ trend }}</a> - <i>{{ trend.user }}</i></p>
<p><i>Posted On: </i>{{ trend.date}}</p>
</div>
<br>
<div class="qtns2">
Most Questions By:
<a href="{% url 'accounts:profile' trend.user %}" style="text-decoration:none;">
<p>{{ trend.user }}</p>
</a>
</div>
</div>
</div>
</div>
<br>
<!-- pagination for the limited display of questions -->
<nav aria-label='pagination'>
{% if results.has_other_pages %}
<ul class="pagination">
{% if results.has_previous %}
<li class="page-item"><a class="page-link" href="?page={{ results.previous_page_number }}">«</a></li>
{% else %}
<li class="page-item disabled"><span class="page-link">«</span></li>
{% endif %} {% for i in results.paginator.page_range %} {% if results.number == i %}
<li class=" page-item active"><span class="page-link">{{ i }} <span class="sr-only">(current)</span></span>
</li>
{% else %}
<li class="page-item"><a class="page-link" href="?page={{ i }}">{{ i }}</a></li>
{% endif %} {% endfor %} {% if questions.has_next %}
<li class="page-item"><a class="page-link" href="?page={{ results.next_page_number }}">»</a></li>
{% else %}
<li class=" page-item disabled"><span class="page-link">»</span></li>
{% endif %}
</ul>
</nav>
</div>
{% endif %} {% endblock %}
All other pages are working, but the home page is returning reverse for 'details' ..... not found. What seems to be the problem, I can't figure it out. Can anyone please look at my code and tell me my mistake. Thanks in advance.

Answer 1

Every time you encounter an error you need to have a debugging strategy. In NoReverseMatch case the strategy would be:
Find all the cases where reverse for 'details' is called.
Check that cases validate by asking yourself three questions:
Is object in the context?
Is field (or key/value) you're trying to get part of this object?
Is value as expected?
All answers must be yes. If the answer is no, fix it.
Cases where reverse for 'details' is called are:
<a href="{% url 'main:details' q.slug %}" id="questions">
<a href="{% url 'main:details' trend.slug %}" style="text-decoration:none;">
Are q and trend in the context? q is as part of results object, that is a yes and trend isn't in the context, because you commented that part of the code in your views. trend.slug thus returns nothing and reverse for 'details' with nothing is not found, because slug is expected.
If you fix this, this error should go away.