Can tornado handle pagination? - rest

Question

Django REST framework let you set a Pagination.
When we make a request it returns a JSON object, with a 'paging' attribute that has 'next' and/or 'previous' attributes containing urls of other pages (if they exist).
Does Tornado provide an option to set Pagination?
I have searched the web for tornado pagination example, but could not find any.
Any help is appreciated.
Thanking you in advance.

Answer 1

Nope, because pagination needs to work pretty closely with the database, and Tornado is DB agnostic.
Here's a UI module that I use; you need a count of your total results, as well as the results for the page (this doesn't limit those results for you, if just builds the pagination links):
from __future__ import division
import math
import urlparse
import urllib
import tornado.web
def update_querystring(url, **kwargs):
base_url = urlparse.urlsplit(url)
query_args = urlparse.parse_qs(base_url.query)
query_args.update(kwargs)
for arg_name, arg_value in kwargs.iteritems():
if arg_value is None:
if query_args.has_key(arg_name):
del query_args[arg_name]
query_string = urllib.urlencode(query_args, True)
return urlparse.urlunsplit((base_url.scheme, base_url.netloc,
base_url.path, query_string, base_url.fragment))
class Paginator(tornado.web.UIModule):
"""Pagination links display."""
def render(self, page, page_size, results_count):
pages = int(math.ceil(results_count / page_size)) if results_count else 0
def get_page_url(page):
# don't allow ?page=1
if page <= 1:
page = None
return update_querystring(self.request.uri, page=page)
next = page + 1 if page < pages else None
previous = page - 1 if page > 1 else None
return self.render_string('uimodules/pagination.html', page=page, pages=pages, next=next,
previous=previous, get_page_url=get_page_url)
Here's the module template (uimodules/pagination.html in the above example):
{% if pages > 1 %}
<div class="pagination pagination-centered">
<ul>
<li{% if previous %}>«{% else %} class="disabled"><span>«</span></li>{% end %}
{% for page_num in xrange(1, pages + 1) %}{# 1-index range #}
<li{% if page_num != page %}>{{ page_num }}{% else %} class="active"><span>{{ page_num }}</span></li>{% end %}
{% end %}
<li{% if next %}>»{% else %} class="disabled"><span>»</span></li>{% end %}
</ul>
</div>
{% end %}
Don't forget to tell your tornado app about the module.
Finally, to actually use it:
{% for result in results %}
<p>{{ result }}</p>
{% end %}
{% module Paginator(page, page_size, results_count) %}
Hope that helps!