| .. _tutorials.gettingstarted.templates: |
| |
| 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 <http://code.google.com/appengine/docs/python/tools/libraries.html#Django>`_ |
| for information on using supported Django versions. |
| |
| |
| Using Django Templates |
| ---------------------- |
| Add the following import statements at the top of helloworld/helloworld.py:: |
| |
| 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): |
| guestbook_name=self.request.get('guestbook_name') |
| greetings_query = Greeting.all().ancestor( |
| guestbook_key(guestbook_name)).order('-date') |
| greetings = greetings_query.fetch(10) |
| |
| if users.get_current_user(): |
| url = users.create_logout_url(self.request.uri) |
| url_linktext = 'Logout' |
| else: |
| 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: |
| |
| .. code-block:: html+django |
| |
| <html> |
| <body> |
| {% for greeting in greetings %} |
| {% if greeting.author %} |
| <b>{{ greeting.author.nickname }}</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> |
| </form> |
| |
| <a href="{{ url }}">{{ url_linktext }}</a> |
| </body> |
| </html> |
| |
| 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. |
| |
| .. note:: |
| 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"``. |
| |
| |
| Next... |
| ------- |
| Every web application returns dynamically generated HTML from the application |
| code, via templates or some other mechanism. Most web applications also need |
| to serve static content, such as images, CSS stylesheets, or JavaScript files. |
| For efficiency, App Engine treats static files differently from application |
| source and data files. You can use App Engine's static files feature to serve |
| a CSS stylesheet for this application. |
| |
| Continue to :ref:`tutorials.gettingstarted.staticfiles`. |
