Django：在组上过滤 ListView/在列表上迭代查询集

Question

Given a User can belong to more than one Group, I would like to ask how to filter on Groups in the below scenario.

In Django I have a ListView showing a product list .

• I have two groups: Company_1, Company_2.

• I have 5 users: Worker_1, Worker_2, Worker_3, Worker_4, Inspector

• Worker_1, Worker_2, belongs to "Company_1"

• Worker_3, Worker_4, belongs to "Company_2"
• "Inspector" can inspect all Products from both Companies

Inspector has no superuser status or staff status, It should be seen as a normal user that belongs to two groups ['Company_1', 'Company_2']

Desired functionality:

Worker_1 register their own manufactured products in the application and can see a list of all products manufactured by Company_1.

Inspector can see all products, from Company_1 and Company_2

In the below code attempts, however, Inspector cannot see any products.

As Inspector belongs to ['Company_1', 'Company_2'] I need a way to check each Group membership in the list against the Group registered for a product. Please note that below are simplified into two groups but in reality x number of groups and users.

in models.py

from django.contrib.auth.models import User

class Product(models.Model):
    worker = models.ForeignKey(User, blank=True, on_delete=models.CASCADE)
    company = models.CharField(max_length=100, null=True, blank=True)

    def save(self, *args, **kwargs):
        self.company = list(self.worker.groups.all().values_list('name', flat=True))
        super(Product, self).save(*args, **kwargs)

within views.py

class ProductListView(LoginRequiredMixin, ListView):
    model = Product
    template_name = 'product_list.html'

    def get_queryset(self):
        queryset = super(ProductListView, self).get_queryset()
        return queryset.filter(company__contains=list(self.request.user.groups.all().values_list('name', flat=True)))

Answer 1

Since your definition of the inspector is clear, we can then add some conditions in the get_queryset function. Here is a pseudo-code:

from django.contrib.auth.models import User, Group

class ProductListView(LoginRequiredMixin, ListView):
    model = Product
    template_name = 'product_list.html'

    def get_queryset(self):
        Company1 = Group.objects.get(name='Company1')
        Company2 = Group.objects.get(name='Company2')
        inspectors = User.objects.filter(groups=Company1 and groups=Company2).distinct() 
        if self.request.user in inspectors:
            return queryset.filter(company=Company1 or company=Company2).distinct().values_list('name', flat=True)))
        return queryset.filter(company__contains=list(self.request.user.groups.all().values_list('name', flat=True)))

I hope this helps, let me know if it's not working :)

Answer 2

I came up with a really ugly solution, but have to work for now. Ideally, I need to figure out a dynamic way to express this. The real problem was to dynamically construct filters and combine those, especially with the manual construct of " | ". There might exist a better solution, but for now I couldn't find it, or figure it out.

class ProductListView(LoginRequiredMixin, ListView):
    model = Product
    template_name = 'product_list.html'

    def get_queryset(self):
        queryset = super(ProductListView, self).get_queryset()

        f = []
        for g in self.request.user.groups.all():
            f.append(f'{g}')

        d = len(f)

        if d == 0:
            g = queryset.filter(company__contains=f"")
        elif d == 1:
            g = queryset.filter(company__contains=f[0])
        elif d == 2:
            g = queryset.filter(company__contains=f[0]) | queryset.filter(company__contains=f[1])
        elif d == 3:
            g = queryset.filter(company__contains=f[0]) | queryset.filter(company__contains=f[1]) \
                | queryset.filter(company__contains=f[2])
        elif d == 4:
            g = queryset.filter(company__contains=f[0]) | queryset.filter(company__contains=f[1]) \
                | queryset.filter(company__contains=f[2]) | queryset.filter(company__contains=f[3])
        elif d == 5:
            g = queryset.filter(company__contains=f[0]) | queryset.filter(company__contains=f[1]) \
                | queryset.filter(company__contains=f[2]) | queryset.filter(company__contains=f[3]) \
                | queryset.filter(company__contains=f[4])
        elif d == 6:
            g = queryset.filter(company__contains=f[0]) | queryset.filter(company__contains=f[1]) \
                | queryset.filter(company__contains=f[2]) | queryset.filter(company__contains=f[3]) \
                | queryset.filter(company__contains=f[4]) | queryset.filter(company__contains=f[5])
        else:
            g = queryset

        return g