django vote system failing

Question

I am Confused. I am trying to set a vote system for a post in a blog. But Django always sums on the vote posive side,

/blog/models.py

class Post(models.Model):
    STATUS_CHOICES = (
        ('draft', 'Draft'),
        ('published', 'Published'),
    )
    title = models.CharField(max_length=250)
    slug = models.SlugField(max_length=250,
                            unique_for_date='publish')
    author = models.ForeignKey(User,
                              on_delete=models.CASCADE,
                              related_name='blog_posts')
    body = models.TextField()
    publish = models.DateTimeField(default=timezone.now)
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)
    status = models.CharField(max_length=10,
                              choices=STATUS_CHOICES,
                              default='draft')
    post_pos = models.IntegerField(default=0)
    post_neg = models.IntegerField(default=0)

    objects = models.Manager() # The default manager.
    published = PublishedManager() # Our custom manager.

    class Meta:
        ordering = ('-publish',)

    def __str__(self):
        return self.title

    def get_absolute_url(self):
        return reverse('blog:post_detail',
                       args=[self.publish.year,
                             self.publish.month,
                             self.publish.day, self.slug])

/blog/urls.py

urlpatterns = [
    path('', views.PostListView.as_view(), name='post_list'),
    path('<int:year>/<int:month>/<int:day>/<slug:post>/',
        views.post_detail,
        name='post_detail'),
    path('<int:post_id>/share/',views.post_share, name='post_share'),
    path('<int:post_id>/',views.positive_post, name='positive_post'),
    path('<int:post_id>/',views.negative_post, name='negative_post'),
]

blog/views.py

 def positive_post(request,post_id):
    obj = Post.objects.get(pk=post_id)
    obj.post_pos += 1
    obj.save()
    print ('positive')
    return redirect(obj.get_absolute_url())

    
def negative_post(request,post_id):
    obj = Post.objects.get(pk=post_id)
    obj.post_neg += 1
    obj.save()
    print ('negative')
    return redirect(obj.get_absolute_url())

template:

  <p>
    <a href="{% url 'blog:positive_post' post.id %}">
      VOTE UP {{ post.post_pos}}
  </p>
  <p>
    <a href="{% url 'blog:negative_post' post.id %}">
      VOTE DOWN {{ post.post_neg}}
  </p>

no matter if I click vote up or vote down always sums in obj.post_pos ???????? thanks to those print('positive), and print('negative') of views.py I know it is always taken positive_post func from views.

positive
[14/Sep/2020 19:04:12] "GET /blog/2/ HTTP/1.1" 302 0
[14/Sep/2020 19:04:12] "GET /blog/2020/8/17/post-number-2/ HTTP/1.1" 200 1284

Anyone knows what is happening??

Answer 1

Both paths resolve to the same URL. Indeed if you look at what Django generates for {% url 'blog:positive_post' post.id %} and {% url 'blog:negative_post' post.id %} , it will both return / post.id , with post.id the filled in .id of the post . So Django will fire the first view that matches in the list of paths.

You should make the paths non-overlapping, for example with:

    path('<int:post_id>/',views.positive_post, name='positive_post'),
    path('<int:post_id>/',views.negative_post, name='negative_post'),

---

Note :Section 9 of the HTTP protocol specifies that requests like GET and HEAD should not have side-effets, so you should not change entities with such requests. Normally POST, PUT, PATCH, and DELETE requests are used for this. In that case you make a small <form> that will trigger a POST request, or you use some AJAX calls.