How to use url variables in class based views

Question

I'm having problems with the url variables and the class based views, but mostly in the html or template because I don't know how to represent it, I'll show you the code so you can understand.

urls.py

app_name = 'app1'

urlpatterns = [
    path('add_post/<str:sym>',AddPostView.as_view(), name='addpost'),
]

views.py

class AddPostView(CreateView):
    model = Post
    form_class = PostForm
    template_name = 'app1/createpost.html'

    def get_queryset(self):
        ala = Post.objects.filter(stock__symbol=self.kwargs['sym'])
        return ala

models.py

class StockNames(models.Model):
    name = models.CharField(max_length=255)
    symbol = models.CharField(max_length=255)

    def __str__(self):
        return self.symbol

        
    

class Post(models.Model):
    title = models.CharField(max_length= 255)
    header_image = models.ImageField(null = True, blank = True, upload_to = 'images/')
    author = models.ForeignKey(User, on_delete=models.CASCADE)
    body = RichTextField(blank = True, null = True)
    #body = models.TextField()
    post_date = models.DateField(auto_now_add=True)
    category = models.CharField(max_length=255, default='coding')
    snippet = models.CharField(max_length=255)
    likes = models.ManyToManyField(User, related_name = 'blog_posts')
    stock = models.ForeignKey(StockNames, null=True, on_delete = models.CASCADE)

    def total_likes(self):
        return self.likes.count()

    def __str__(self):
        return self.title + ' | ' + str(self.author)
    
    def get_absolute_url(self):
        return reverse('app1:article-detail', args=(self.id,))

Template (I'm having problems with Add Post(current) )

{% extends "app1/base.html" %}
    {% block body_block %}
    
    
    {% if stock_sym %}
    <h1> {{sym}} </h1>
    <a href ="{% url 'app1:addpost' StockNames.symbol %}">Add Post<span class="sr-only">(current)</span></a> 
        {% if stocks %}
    
        
        <ul>
        {% for post in stocks %}
        <li><a href="{% url 'app1:article-detail' post.pk %}">{{sym}}</a> -
            {{post.author}} - <small>{{post.post_date}}</small> - 
            {% if user.is_authenticated %}
            <small><a href="{% url 'app1:updatepost' post.pk %}">Edit</a></small><small>
            <a href="{% url 'app1:deletepost' post.pk %}">- Delete</a>  
            </small></li>
            {% endif %}
            {{post.body|slice:":200"|safe}} 
    
        {% endfor %}
        </ul>
    {% else %}
    <h1>No posts yet</h1>
    {% endif %}
    {% else %}
    <h1>hey</h1>
    {% endif %}
    {% endblock %}

trace

Traceback (most recent call last):
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\core\handlers\exception.py", line 47, in inner
    response = get_response(request)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\core\handlers\base.py", line 202, in _get_response
    response = response.render()
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\template\response.py", line 105, in render
    self.content = self.rendered_content
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\template\response.py", line 83, in rendered_content
    return template.render(context, self._request)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\template\backends\django.py", line 61, in render
    return self.template.render(context)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\template\base.py", line 170, in render
    return self._render(context)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\template\base.py", line 162, in _render
    return self.nodelist.render(context)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\template\base.py", line 938, in render
    bit = node.render_annotated(context)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\template\base.py", line 905, in render_annotated
    return self.render(context)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\template\loader_tags.py", line 150, in render
    return compiled_parent._render(context)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\template\base.py", line 162, in _render
    return self.nodelist.render(context)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\template\base.py", line 938, in render
    bit = node.render_annotated(context)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\template\base.py", line 905, in render_annotated
    return self.render(context)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\template\defaulttags.py", line 312, in render
    return nodelist.render(context)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\template\base.py", line 938, in render
    bit = node.render_annotated(context)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\template\base.py", line 905, in render_annotated
    return self.render(context)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\template\defaulttags.s.py", line 446, in render
    url = reverse(view_name, args=args, kwargs=kwargs, current_app=current_app)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\urls\base.py", line 8 87, in reverse
    return iri_to_uri(resolver._reverse_with_prefix(view, prefix, *args, **kwargs))
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\urls\resolvers.py", l line 685, in _reverse_with_prefix
    raise NoReverseMatch(msg)
django.urls.exceptions.NoReverseMatch: Reverse for 'addpost' with no arguments not found. 1 pattttern(s) tried: ['app1/add_post/(?P<sym>[^/]+)$']

Thanks in advance! So the main problem is putting the link in the href of the template, I don't know how to express it.

I updated the trace error

Sebastian Nin
– Sebastian Nin

2020-08-15 18:19:37 +00:00
Commented Aug 15, 2020 at 18:19 — Sebastian Nin
– Sebastian Nin, Commented Aug 15, 2020 at 18:19

Rick · Accepted Answer · 2020-08-16 06:19:12Z

1

**EDIT

Try:

<a href ="{% url 'app1:addpost' sym=sym %}">Add Post<span class="sr-only">(current)</span></a>

Views.py - try switching your method for get_context_data:

class AddPostView(CreateView):
    model = Post
    form_class = PostForm
    template_name = 'app1/createpost.html'

    def get_context_data(self, *args, **kwargs):
        context = super().get_context_data(**kwargs)
        context.update(
            sym=get_object_or_404(StockNames, StockNames.symbol)
        )
        return context

Here is a link to the appropriate Django documentation for more info:

https://docs.djangoproject.com/en/3.1/topics/class-based-views/generic-display/#adding-extra-context

edited Aug 16, 2020 at 6:19

answered Aug 15, 2020 at 18:29

Rick

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1 Comment

Sebastian Nin Over a year ago

It shows an error that says Reverse for 'addpost' with keyword arguments '{'sym': ''}' not found. 1 pattern(s) tried: ['app1/add_post/(?P<sym>[^/]+)$']

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