Qs -- cannot pass the challenge :( HELP!!!

Question

In this challenge, I have to look for products with

1) rating >= 8

2) created_at in latest 4 weeks in the 'product_detail' function

Here's my code:

def product_detail(request, pk):
    product = get_object_or_404(models.Product, pk=pk)
    fours_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})

I took several discussions as references, but just couldn't pass the challenge!

I'm wondering

1) Is the 'all()' necessary since we are already using 'filter()'?

2) What's the difference between doing 'order()' before and after the 'filter()'?

Above these, I cannot figure out what might be the problem. Even though I've tried to test with these two variables (i.e. I tried not just the above code), it still couldn't pass the challenge. :(

Can anyone help?

Answer 1 · 2019-09-16T20:39:01Z

September 16, 2019 8:39pm

Good job, your code works for me!

Those are good questions to ask. The Django docs don't answer all the questions you might have, but are pretty excellent compared to other frameworks (I'm looking at you Laravel, good framework, bad docs).

When I did the challenge, I used your code and cut-and-pasted and removed the .all() on the end, but it would work just fine if you leave it in. See below:

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')
    return render(request, 'products/product_detail.html', {'product': product, 'reviews': reviews})

Django specifics on queries-- https://docs.djangoproject.com/en/2.2/topics/db/queries/

My take on your questions

1) Like you predicted... all() is not necessary

2) As you would expect, it is a convention not a requirement to always perform the "order_by" last. There are two reasons for this-- the "ORDER BY" clause always comes last in conventional SQL syntax; filtering is by definition "reductionist" so the computer saves work by sorting the fewest number of rows, thus enhancing efficiency.

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oliverchou

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Qs -- cannot pass the challenge :( HELP!!!

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Jeff Muday

Jeff Muday

oliverchou

oliverchou