Failed to understand syntax

Mayur Bagul

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Apr 12, 2019, 9:25:15 AM4/12/19

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Hello coders,

I'm here to understand line of code which im unable to understand how it work.

i'm looking forward to get help from you.

code is given below :

from django.shortcuts import render

from .models import Question

def index(request):

latest_question_list = Question.objects.order_by('-pub_date')[:5]

context = {'latest_question_list': latest_question_list}

return render(request, 'polls/index.html', context)

- in the code above i'm looking forward to know about bold and highlighted part how it work ?

Test Bot

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Apr 12, 2019, 10:01:49 AM4/12/19

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The part you want to understand is same as ORDER BY clause in SQL. The slicing will provide only the top 5 results. By default the order_by sorts in ascending order only. But providing a "-" would make it to sort in descending order.

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Mayur Bagul

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Apr 13, 2019, 3:38:26 AM4/13/19

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Hello Judge95,

thanks for useful information but i want to know how [:5] is used without . operator and how it is work.

thanking you.

On Friday, April 12, 2019 at 7:31:49 PM UTC+5:30, OnlineJudge95 wrote:

The part you want to understand is same as ORDER BY clause in SQL. The slicing will provide only the top 5 results. By default the order_by sorts in ascending order only. But providing a "-" would make it to sort in descending order.

On Fri, Apr 12, 2019, 6:56 PM Mayur Bagul <mayur...@gmail.com> wrote:

Hello coders,

I'm here to understand line of code which im unable to understand how it work.
i'm looking forward to get help from you.

code is given below :

from django.shortcuts import render

from .models import Question

def index(request):
latest_question_list = Question.objects.order_by('-pub_date')[:5]
context = {'latest_question_list': latest_question_list}
return render(request, 'polls/index.html', context)

- in the code above i'm looking forward to know about bold and highlighted part how it work ?

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For more options, visit https://groups.google.com/d/optout.

On Fri, Apr 12, 2019, 6:56 PM Mayur Bagul <mayur...@gmail.com> wrote:

Hello coders,

I'm here to understand line of code which im unable to understand how it work.
i'm looking forward to get help from you.

code is given below :

from django.shortcuts import render

from .models import Question

def index(request):
latest_question_list = Question.objects.order_by('-pub_date')[:5]
context = {'latest_question_list': latest_question_list}
return render(request, 'polls/index.html', context)

- in the code above i'm looking forward to know about bold and highlighted part how it work ?

--
You received this message because you are subscribed to the Google Groups "Django users" group.

To unsubscribe from this group and stop receiving emails from it, send an email to django...@googlegroups.com.

Test Bot

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Apr 13, 2019, 3:58:39 AM4/13/19

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That is because

Question.objects.order_by("-pub_date")

would give you a list of all records so you can simply apply slicing without the use of . operator.

For understanding purpose, you can break down your code as

result = Question.objects.order_by("-pub_date")
latest_question_list = result[:5]

This is a feature provided by Python itself.

Would suggest going through the Django docs about ORM in case you have not.

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Mayur Bagul

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Apr 14, 2019, 3:01:14 AM4/14/19

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Thank a lot for your valuable information on asked topic. My double is clear now.
Thanks to you and community.

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