Django No Reverse Match Error - django

Question

I've been working on this error for the better part of a week and this is the error I keep receiving:
>
NoReverseMatch at /practice/practice/2/saleinfoedit/
Reverse for 'car_detail' with keyword arguments '{'pk': ''}' not found. 1 pattern(s) tried: ['practice/practice/(?P<pk>\\d)$']
I've simplified the code to what are the relevant parts of the error, I think. The idea is to have a list page of cars and when you click on the car link you can edit the Sale History of the vehicle. Eventually I'll setup formsets for this part, but babysteps. Here's the relevant code:
models.py
class Car(models.Model):
car_name = models.CharField(max_length=200)
color = models.CharField(max_length=200)
age = models.CharField(max_length=200)
def get_absolute_url(self):
return reverse('practice:car_detail',kwargs={'pk':self.pk})
def __str__(self):
return '%s' %(self.car_name)
class SaleInfo(models.Model):
car_name = models.ForeignKey(Car, on_delete=models.CASCADE,)
price = models.CharField(max_length=100)
date = models.CharField(max_length=100)
comments = models.CharField(max_length=200)
def __str__(self):
return '%s' %(self.car_name)
def get_absolute_url(self):
return reverse('practice:car_detail',kwargs={'pk':self.pk})
views.py
class IndexView(generic.ListView):
template_name = 'practice/carlist.html'
context_object_name = 'latest_car_list'
def get_queryset(self):
return Car.objects.all()
class DetailView(generic.DetailView):
model = Car
form_class = CarForm
template_name = 'practice/car_detail.html'
class UpdateView(generic.UpdateView):
model = Car
form_class = CarFormEdit
class SaleInfoUpdateView(generic.UpdateView):
model = SaleInfo
form_class = SaleInfoFormEdit
template_name = 'practice/saleinfo_form.html'
urls.py
app_name = 'practice'
urlpatterns = [
url(r'^$', views.IndexView.as_view(), name='index'), # shows lists of Cars via Car Name
url(r'^practice/(?P<pk>\d)$', views.DetailView.as_view(), name='car_detail'),
url(r'^practice/(?P<pk>\d)/edit/$', views.UpdateView.as_view(), name='car_edit'),
url(r'^practice/(?P<pk>\d)/saleinfoedit/$', views.SaleInfoUpdateView.as_view(), name='saleinfo_edit'),
]
car_detail.html
{% extends 'practice/car_base.html' %}
{% block post_content %}
<div class="col-md-8">
<a class='btn btn-primary' href="{% url 'practice:car_edit' pk=car.pk %}">
<span class='glyphicon glyphicon-pencil'></span>
</a>
<p>{{ car.car_name|safe }}</p>
<p>{{ car.color|safe }} {{ car.age|safe }} </p>
<a class='btn btn-primary' href="{% url 'practice:saleinfo_edit' pk=car.pk %}">
<span class='glyphicon glyphicon-pencil'> SaleInfo</span>
</a>
</div>
{% endblock %}
saleinfo_form.html
{% extends 'practice/car_base.html' %}
{% block post_content %}
{% load bootstrap3 %}
<form class="" action="" method="post">
{% csrf_token %}
{% bootstrap_form form %}
<!-- {{form.as_p}} -->
<input type="submit" name="" value="Update">
</form>
{% endblock %}
I can post my templates too if necessary. I'm sure it's something simple I keep looking past, but after a few days I'm lost.

Answer 1

According to the error message, the parameter pk you have given to the {% url %} tag is empty:
...with keyword arguments '{'pk': ''}'
There are two common reasons for that:
You have a typo in your variable name in your template.
You are creating a new object, so it doesn't have an ID/PK yet.
Your templates look fine though, so here is how I would debug it:
Remove {% url %} tags one after the other until you find the actual culprit.
Print out the variable you pass as keyword argument pk.
One more thing: \d matches exactly one digit, so your URL patterns will stop working once you have more than 9 cars. You have to add a + to match one or more digits:
url(r'^practice/(?P<pk>\d+)/edit/$', views.UpdateView.as_view(), name='car_edit'),
Also, like #wencakisa remarked, URLs in Django usually end with a slash, but that isn't mandatory.
Edit: I just noticed two more things:
your SaleInfo.get_absolute_url method uses practice:car_detail. Shouldn't that be saleinfo_edit?
in the car_detail.html template, you use {% url 'practice:saleinfo_edit' pk=car.pk %}. That won't work. If there is only one SaleInfo per car, use a OneToOneField instead of a ForeignKey in your model. Then you can do something like:
{% if car.sale_info %}
{% url 'practice:saleinfo_edit' pk=car.sale_info.pk %}
{% endif %}