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Python Django ORM Total Control Annotate

Itai Mutemeri
Itai Mutemeri
111 Points
Posted by Itai Mutemeri
Itai Mutemeri
111 Points

Annotate returning incorrect avg

I'm trying to get the average of each product's reviews. Seems straightforward enough, but feedback keeps telling me I'm wrong. Here's the line of code I added:

review = models.Product.objects.annotate(avg_rating=Avg('review'))

Any suggestions?

products/views.py 
import datetime

from django.db.models import Q, Avg
from django.shortcuts import render, get_object_or_404

from . import models


def good_reviews(request):
    reviews = models.Review.objects.filter(rating__gte=3)
    return render(request, 'products/reviews.html', {'reviews': reviews})


def recent_reviews(request):
    six_months_ago = datetime.datetime.today() - datetime.timedelta(days=180)
    reviews = models.Review.objects.exclude(created_at__lt=six_months_ago)
    return render(request, 'products/reviews.html', {'reviews': reviews})


def product_detail(request, pk):
    product = get_object_or_404(models.Product, pk=pk)
    four_weeks_ago = datetime.datetime.today() - datetime.timedelta(weeks=4)
    reviews = product.review_set.filter(Q(rating__gte=8)|Q(created_at__gte=four_weeks_ago)).order_by('-created_at').all()
    return render(request, 'products/product_detail.html', {'product': product, 'reviews': reviews})


def product_list(request):
    products = models.Product.objects.all()
    review = models.Product.objects.annotate(avg_rating=Avg('review'))
    return render(request, 'products/product_list.html', {'products': products,'review':review})
Richard Li
Richard Li
9,751 Points
Richard Li
Richard Li
9,751 Points

Glad to help

1 Answer

Richard Li
Richard Li
9,751 Points
Richard Li
Richard Li
9,751 Points

Annotation is not a separate set of objects to pass in as context. It is something annotated to each entry of data.

try annotate each model in models.Products.all() with the average of "review__rating" before assigning them to the name 'products'. Then you will get the right answer.

Itai Mutemeri
Itai Mutemeri
111 Points
Itai Mutemeri
Itai Mutemeri
111 Points

Ahhh. I see. Tried it and it worked. Thanks a bunch, Richard.