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@mishudark
Created April 23, 2011 15:51
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paginator compatible with pymongo and mongoengine
# pagination.py
class Paginator(object):
def __init__(self, query, per_page):
"""Initialize a paginator.
Arguments:
- query -- queryset from pymongo or mongoengine
- per_page -- number of items per page
Usage: ::
latest_blog_posts = BlogPost.objects()
paginator = Paginator(latest_blog_posts, 10)
# get first page of blog posts
page = paginator.page(1)
for post in page.object_list:
# do something with BlogPost instance
"""
from math import ceil
self.query = query
self.per_page = per_page
self._count = query.count()
self.page_count = int(ceil(float(self._count) / per_page))
def page_range(self):
"""Return a 1-based list of page numbers valid for this ``Paginator``.
"""
return range(1, self.page_count + 1)
def page(self, page_number):
"""1-based access to pages.
"""
if not isinstance(page_number, int):
try:
page_number = int(page_number)
except:
raise Exception("Page numbers must be integers.")
if page_number < 1:
raise Exception("%s is less than 1." % page_number)
if page_number > self.page_count:
raise Exception("Page %s contains no results." \
% page_number)
# apply pagination offsets and limits
start_offset = self.per_page * (page_number-1)
end_offset = self.per_page + start_offset
query = self.query[start_offset:end_offset]
# return Page object
object_list = list(query)
return Page(page_number, self.page_count, object_list, self._count)
class Page(object):
def __init__(self, object_list, page_number, page_count, all_objects_count):
"""A page of data generated by ``Paginator``.
"""
self.object_list = object_list
self.page_number = page_number
self.page_count = page_count
self.all_objects_count = all_objects_count
def __repr__(self):
return u"<Page %s of %s>" % (self.page_number, self.page_count)
def has_previous(self):
return self.page_number > 1
def has_next(self):
return self.page_number < self.page_count
def has_other_pages(self):
return self.has_next() or self.has_previous()
def next_page_number(self):
return self.page_number + 1
def previous_page_number(self):
return self.page_number - 1
# pagination_tests.py
import unittest
from mongoengine.document import Document
from mongoengine import fields, connect
from pagination import Paginator
class PaginationTest(unittest.TestCase):
def setUp(self):
connect(db='me_pagination_tests')
class BlogPost(Document):
title = fields.StringField()
self.BlogPost = BlogPost
post_1 = BlogPost(title="Post #1")
post_1.save()
post_2 = BlogPost(title="Post #2")
post_2.save()
post_3 = BlogPost(title="Post #3")
post_3.save()
post_4 = BlogPost(title="Post #4")
post_4.save()
post_5 = BlogPost(title="Post #5")
post_5.save()
def test_paginator(self):
"""Ensure paginator page counts and ranges are correct.
"""
query = self.BlogPost.objects()
paginator = Paginator(query, 2)
# test count and range
self.assertEqual(paginator.page_count, 3)
self.assertEqual(paginator.page_range(), [1, 2, 3])
def test_page(self):
"""Ensure a ``Page`` returned by a ``Paginator`` is correct.
"""
# get some pages
first_page = Paginator(self.BlogPost.objects(), 2).page(1)
second_page = Paginator(self.BlogPost.objects(), 2).page(2)
third_page = Paginator(self.BlogPost.objects(), 2).page(3)
# validate object list's length
# self.assertEqual(len(first_page.object_list), 2)
self.assertEqual(len(second_page.object_list), 2)
self.assertEqual(len(third_page.object_list), 1)
# validate first page's directions
self.assertEqual(first_page.has_next(), True)
self.assertEqual(first_page.has_previous(), False)
self.assertEqual(first_page.has_other_pages(), True)
self.assertEqual(first_page.next_page_number(), 2)
self.assertEqual(first_page.previous_page_number(), 0)
# validate second page
self.assertEqual(second_page.has_next(), True)
self.assertEqual(second_page.has_previous(), True)
self.assertEqual(second_page.has_other_pages(), True)
self.assertEqual(second_page.next_page_number(), 3)
self.assertEqual(second_page.previous_page_number(), 1)
# validate third page
self.assertEqual(third_page.has_next(), False)
self.assertEqual(third_page.has_previous(), True)
self.assertEqual(third_page.has_other_pages(), True)
self.assertEqual(third_page.next_page_number(), 4)
self.assertEqual(third_page.previous_page_number(), 2)
def tearDown(self):
self.BlogPost.drop_collection()
if __name__ == '__main__':
unittest.main()
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