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Python Django ORM Total Control select_related

Posted by Pridemore Viriri
Pridemore Viriri
10,570 Points

Django ORM

The view for an individual Review always has to talk about the Product that it relates to. This means we have to do at least two queries, one for the Review and one for the Product.

Can you use select_related on the review_detail view to get the Product at the same time and reduce our queries to 1?

kindly assist guys

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