How to display sum of disctinct items in django? - django

Question

I would like to display sum all the distinct categories of the products that belongs to the user. I searched on the web, but all the things that I tried doensn't work. You may find the models,view and template below. It doesn't give me anything at the html.
Model:
class Product(models.Model):
user = models.ForeignKey(User, on_delete=models.CASCADE,related_name='products')
category = models.CharField(max_length=120)
brand = models.CharField(max_length=120)
product = models.CharField(max_length=120)
price = models.DecimalField(decimal_places=2,max_digits=100)
class Comp_Product(models.Model):
product = models.ForeignKey(Product,on_delete=models.CASCADE, related_name="comp_products")
competitor = models.URLField()
price = models.DecimalField(decimal_places=2,max_digits=100)
change = models.FloatField()
stock = models.BooleanField()
last_update = models.DateField(auto_now_add=True)
View:
class DashboardList(ListView):
template_name='dashboard_by_user.html'
def get_queryset(self):
return Product.objects.filter(user=self.request.user).annotate(count_category=Count('category',distinct=True)).aggregate(sum_category=Sum('count_category'))
template:
{% for product in product_list %}
{{product.sum_category}}
{%endfor%}

Answer 1

welcome to stackoverflow,
I'm assuming that you want to count the number of distinct categories for the given user. This can be done like this:
views.py:
from django.views.generic.list import ListView
from .models import Product
class DashboardList(ListView):
template_name = 'dashboard_by_user.html'
def get_queryset(self):
return Product.objects.filter(user=self.request.user)
def get_context_data(self, **kwargs):
context = super().get_context_data(**kwargs)
Products = context['object_list']
context['distinct_category_count'] = Products.values(
'category').distinct().count()
return context
dashboard_by_user.html:
<h1>Products</h1>
<ul>
{% for product in object_list %}
<li>{{ product.brand }} - {{ product.product }} - {{ product.category }}</li>
{% empty %}
<li>No Producs yet.</li>
{% endfor %}
</ul>
<p> Number of distinct categories: {{ distinct_category_count }} </p>
This should give you an output similar to this one: