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Python Django ORM Total Control select_related

Lydia O' Brien
Lydia O' Brien
4,014 Points

I already asked this question, but I believe that now it is too old to find. I am still confused about this question!

Could somebody walk me through this problem and explain theirsteps and how they got it?

products/views.py
import datetime

from django.db.models import Q, Avg
from django.http import Http404
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):
    try:
        product = models.Product.objects.prefetch_related('review_set').get(pk=pk)
    except models.Product.DoesNotExist:
        raise Http404()
    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.annotate(avg_rating=Avg('review__rating')).all()
    return render(request, 'products/product_list.html', {'products': products})


def review_detail(request, product_pk, pk):
    try:
        review = models.Review.objects.get(product_id=product_pk, pk=pk)
    except models.Review.DoesNotExist:
        raise Http404()
    else:
        return render(request, 'products/review_detail.html', {'review': review})

1 Answer

Hi Lydia

You need to get the product for the selected review using select_related.

def review_detail(request, product_pk, pk):
    try:
        review = models.Review.objects.select_related('product').get(pk=pk)
    except models.Review.DoesNotExist:
        raise Http404()
    else:
        return render(request, 'products/review_detail.html', {'review': review})