Using Templates

HTML embedded in code is messy and difficult to maintain. It’s better to use a templating system, where the HTML is kept in a separate file with special syntax to indicate where the data from the application appears. There are many templating systems for Python: EZT, Cheetah, ClearSilver, Quixote, and Django are just a few. You can use your template engine of choice by bundling it with your application code.

For your convenience, the webapp2 module includes Django’s templating engine. Versions 1.2 and 0.96 are included with the SDK and are part of App Engine, so you do not need to bundle Django yourself to use it.

See the Django section of Third-party libraries for information on using supported Django versions.

Using Django Templates

Add the following import statements at the top of helloworld/

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

Replace the MainPage handler with code that resembles the following:

class MainPage(webapp2.RequestHandler):
    def get(self):
        greetings_query = Greeting.all().ancestor(
        greetings = greetings_query.fetch(10)

        if users.get_current_user():
            url = users.create_logout_url(self.request.uri)
            url_linktext = 'Logout'
            url = users.create_login_url(self.request.uri)
            url_linktext = 'Login'

        template_values = {
            'greetings': greetings,
            'url': url,
            'url_linktext': url_linktext,

        path = os.path.join(os.path.dirname(__file__), 'index.html')
        self.response.out.write(template.render(path, template_values))

Finally, create a new file in the helloworld directory named index.html, with the following contents:

    {% for greeting in greetings %}
      {% if %}
        <b>{{ }}</b> wrote:
      {% else %}
        An anonymous person wrote:
      {% endif %}
      <blockquote>{{ greeting.content|escape }}</blockquote>
    {% endfor %}

    <form action="/sign" method="post">
      <div><textarea name="content" rows="3" cols="60"></textarea></div>
      <div><input type="submit" value="Sign Guestbook"></div>

    <a href="{{ url }}">{{ url_linktext }}</a>

Reload the page, and try it out.

template.render(path, template_values) takes a file path to the template file and a dictionary of values, and returns the rendered text. The template uses Django templating syntax to access and iterate over the values, and can refer to properties of those values. In many cases, you can pass datastore model objects directly as values, and access their properties from templates.


An App Engine application has read-only access to all of the files uploaded with the project, the library modules, and no other files. The current working directory is the application root directory, so the path to index.html is simply "index.html".