Django utility to retrieve the next or previous object, given a current object and a queryset.
Project description
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Purpose
django-next-prev provides utilities to get the next or previous item within an ordered, filtered queryset. For example, you could display a link to the next featured post on a post detail page, or show chronological next and previous links for all published posts.
Installation
Download the source from https://pypi.python.org/pypi/django-next-prev/ and run python setup.py install, or:
> pip install django-next-prev
Django 1.8 or higher is required.
Quick start
Given this models.py:
from django.db import models class Category(models.Model): title = models.CharField(max_length=100) class Post(models.Model): title = models.CharField(max_length=100) category = models.ForeignKey(Category, on_delete=models.CASCADE) created = models.DateField() featured = models.BooleanField(default=False) text = models.TextField() class Meta: # order on primary key to make sure it's unique ordering = ('created', 'title', 'pk')
You can do the following
from next_prev import next_in_order, prev_in_order from .models import Post # default ordering first = Post.objects.first() second = next_in_order(first) prev_in_order(second) == first # True last = prev_in_order(first, loop=True) # custom ordering qs = Post.objects.all().order_by('-created', '-pk') newest = qs.first() second_newest = next_in_order(newest, qs=qs) oldest = prev_in_order(newest, qs=qs, loop=True) # filtered qs = Post.objects.filter(featured=True) first_featured = qs.first() second_featured = next_in_order(first_featured, qs=qs)
Ordering considerations
Order fields must be non-nullable.
If results are inconsistent with the order of your queryset, you’re probably ordering on a non-unique combination of fields. For example, ordering = ('sort_order', ) with the duplicate sort_order values. To resolve this, add a unique field to your ordering, i.e. ordering = ('sort_order', 'pk')
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