Query in Django to sort in one table based on result of another table-CodePudding

I have two models listing model is:

class listing(models.Model):
    productTitle= models.CharField(max_length=60)
    description = models.TextField()
    category = models.ForeignKey(category,on_delete=models.CASCADE,null=True)
    productPrice = models.FloatField(default=0.0)
    
    def __str__(self):
        return self.productTitle

my watchlist model is:

    item = models.ForeignKey(listing, on_delete= models.CASCADE)
    watchlist = models.BooleanField(default=False)
    user = models.ForeignKey(User, on_delete=models.CASCADE)

    def __str__(self):
        return self.item

In my index.html I want to show the list item if watchlist attribute is False.

Now, my views.py for index.html is as follows:

def index(request):
    if request.user != "AnonymousUser":
        items= listing.objects.exclude(id=watchlist.objects.filter(user=request.user))
    else:
        items = watchlist.objects.all()
    context = {'items':items}
    return render(request, "auctions/index.html", context)

I couldn't filter the items on listing models based on the result of watchlist model i.e if watchlist=True then I do not want to render items on index.html. Because, I want to render watchlist items in separate pages. How to query in django if there are two models used?

CodePudding user response：

You could have probably do something like this

watch_list = watchlist.objects.filter(wishlist=False, user=request.user.id).values('item')

Then if you want to fetch items, you do like this

items = listing.objects.filter(id__in=watch_list)

CodePudding user response：

from django.db.models import Q    
items = listing.objects.filter(watchlist__isnull=True) | listing.objects.filter(Q(watchlist__user=request.user) & Q(watchlist__watchlist=False))

If my understanding is correct you need to list items which are not in watchlist table too. You could use backwards relation in query. watchlist__isnull=True is for listing the entries not in watchlist table. The second part listing.objects.filter(Q(watchlist__user=request.user) & Q(watchlist__watchlist=False) is the watchlist filter