Introducing Google App Engine Paginator

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Tags: appengine, python

Table of contents

Summary

Need a way to paginate through a GQL query easily? gae_paginator handles the generation of next/previous page URLs, paginates on both unique and non-unique properties, and wants to be as efficient and easy to use as possible.

Getting Started

  1. Download the source and copy the gae_paginator/ folder anywhere inside your App Engine project directory.

  2. That's it! Use it like so, in your handlers:

    import os

from google.appengine.ext.webapp import template
import webapp2

from gae_paginator import Paginator

class YourHandler(webapp2.RequestHandler):

  def get(self):
  paginator = Paginator(YourModel, 'some_column = :1 AND other_column = :2',
                        ['some_value', 'other_value'], expect_duplicates=True,
                        per_page=50, paginate_on='-created')
  page = paginator.get_page(request=self.request)
  path = os.path.join(os.path.dirname(__file__), 'index.html')
  self.response.out.write(template.render(path, {
    'objects': list(page),
    'page': page,
  })

  3. In your django template:

    {% if page.has_previous %}
    <a href="{{ page.get_previous_url }}">&laquo; Previous page</a>
{% endif %}
{% if page.has_next %}
    <a href="{{ page.get_next_url }}">Next page &raquo;</a>
{% endif %}

    Or jinja2 template:

    {% if page.has_previous() %}
     <a href="{{ page.get_previous_url() }}">&laquo; Previous page</a>
{% endif %}
{% if page.has_next() %}
    <a href="{{ page.get_next_url() }}">Next page &raquo;</a>
{% endif %}

Features

  • Simple pagination by key

  • Paginate by non-unique properties with a specified tolerance for duplicates.

  • Example: paginate songs by artist name, 10 songs per page, expect 100 duplicates. Set: expect_duplicates=100

  • Order and paginate by a custom column (Date/DateTime and key supported and tested).
  • Show next and previous buttons only when there is actual data before/after.