CODEWITHSUNDEEP
pythonhtmldjango
Ahmed Wagdi
Ahmed Wagdi

Reputation: 4391

Django URL pattern using pk error

I'm using the latest version of python3 and Django2, trying to do an URL pattern that is dynamic and changes for every different variable, Here are the codes:

urls.py 

path('categories/<int:item_category>/', views.item_category, name="item_category"),

views.py 

def item_category(request, pk):
    item_category = get_object_or_404(Categories, pk=pk)

    return render(request, 'items_modal.html', {'item_category': item_category})

models.py 

class Categories(models.Model):
    category_name  = models.CharField(max_length=30)

    def __str__(self):
        return self.category_name

    def item_category(self):
        return reverse('item_category', args=[self.pk])

home.html

    <div class="table-responsive">
   <table class="table table-hover">
  <thead class="thead-dark">
    <tr>
      <th scope="col"><h2 align="center"> محتويات المخزن</h2></th>
    </tr>
  </thead>
  <tbody>
     {% for cat in all_cats %}
    <tr>
      <th scope="row"><a href="{% url 'item_category' item_category.pk %}"" data-toggle="modal" data-target="#exampleModal">{{ cat }}</a></th>

    </tr>
    {% endfor %}
  </tbody>
</table>
</div>

when I try to go to open the home page it gives me the error :

NoReverseMatch at /
Reverse for 'item_category' with arguments '('',)' not found. 1 pattern(s) tried: ['categories\\/(?P<item_category>[0-9]+)\\/$']
Request Method: GET
Request URL:    http://127.0.0.1:8000/
Django Version: 2.0.4
Exception Type: NoReverseMatch
Exception Value:    
Reverse for 'item_category' with arguments '('',)' not found. 1 pattern(s) tried: ['categories\\/(?P<item_category>[0-9]+)\\/$']
Exception Location: C:\Users\Dev3\AppData\Local\Programs\Python\Python36-32\lib\site-packages\django\urls\resolvers.py in _reverse_with_prefix, line 632
Python Executable:  C:\Users\Dev3\AppData\Local\Programs\Python\Python36-32\python.exe
Python Version: 3.6.5
Python Path:    
['C:\\python\\Django\\nothing',
 'C:\\Users\\Dev3\\AppData\\Local\\Programs\\Python\\Python36-32\\python36.zip',
 'C:\\Users\\Dev3\\AppData\\Local\\Programs\\Python\\Python36-32\\DLLs',
 'C:\\Users\\Dev3\\AppData\\Local\\Programs\\Python\\Python36-32\\lib',
 'C:\\Users\\Dev3\\AppData\\Local\\Programs\\Python\\Python36-32',
 'C:\\Users\\Dev3\\AppData\\Local\\Programs\\Python\\Python36-32\\lib\\site-packages']
Server time:    Tue, 24 Apr 2018 09:39:46 +0000

Upvotes: 0

Views: 204

Answers (1)

Alasdair
Alasdair

Reputation: 308849

Reverse for 'item_category' with arguments '('',)' not found. 1 pattern(s) tried: ['categories\\/(?P<item_category>[0-9]+)\\/$']

In the error message, with arguments '('',)' is telling you that the argument in the url tag evaluated to the empty string ''.

Looking at your template, you loop through {% for cat in all_cats %} but then you use item_category.pk inside the loop. You probably want cat.pk:

{% for cat in all_cats %}
<tr>
  <th scope="row"><a href="{% url 'item_category' cat.pk %}" data-toggle="modal" data-target="#exampleModal">{{ cat }}</a></th>
</tr>
{% endfor %}

Upvotes: 2

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