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/usr/share/doc/python3-jinja2/html/_sources/

/usr/share/doc/python3-jinja2/html/_sources

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api.rst.txt	33344	0644	edit dl rm
changelog.rst.txt	48	0644	edit dl rm
extensions.rst.txt	11238	0644	edit dl rm
faq.rst.txt	8119	0644	edit dl rm
index.rst.txt	995	0644	edit dl rm
integration.rst.txt	3565	0644	edit dl rm
intro.rst.txt	4158	0644	edit dl rm
latexindex.rst.txt	83	0644	edit dl rm
nativetypes.rst.txt	1565	0644	edit dl rm
sandbox.rst.txt	3536	0644	edit dl rm
switching.rst.txt	7067	0644	edit dl rm
templates.rst.txt	54540	0644	edit dl rm
tricks.rst.txt	3213	0644	edit dl rm

Edit: /usr/share/doc/python3-jinja2/html/_sources/tricks.rst.txt (3213B)

Tips and Tricks
===============

.. highlight:: html+jinja

This part of the documentation shows some tips and tricks for Jinja2
templates.

.. _null-master-fallback:

Null-Master Fallback
--------------------

Jinja2 supports dynamic inheritance and does not distinguish between parent
and child template as long as no `extends` tag is visited.  While this leads
to the surprising behavior that everything before the first `extends` tag
including whitespace is printed out instead of being ignored, it can be used
for a neat trick.

Usually child templates extend from one template that adds a basic HTML
skeleton.  However it's possible to put the `extends` tag into an `if` tag to
only extend from the layout template if the `standalone` variable evaluates
to false which it does per default if it's not defined.  Additionally a very
basic skeleton is added to the file so that if it's indeed rendered with
`standalone` set to `True` a very basic HTML skeleton is added::

{% if not standalone %}{% extends 'master.html' %}{% endif -%}
    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
    <title>{% block title %}The Page Title{% endblock %}</title>
    <link rel="stylesheet" href="style.css" type="text/css">
    {% block body %}
      <p>This is the page body.</p>
    {% endblock %}

Alternating Rows
----------------

If you want to have different styles for each row of a table or
list you can use the `cycle` method on the `loop` object::

<ul>
    {% for row in rows %}
      <li class="{{ loop.cycle('odd', 'even') }}">{{ row }}</li>
    {% endfor %}
    </ul>

`cycle` can take an unlimited amount of strings.  Each time this
tag is encountered the next item from the list is rendered.

Highlighting Active Menu Items
------------------------------

Often you want to have a navigation bar with an active navigation
item.  This is really simple to achieve.  Because assignments outside
of `block`\s in child templates are global and executed before the layout
template is evaluated it's possible to define the active menu item in the
child template::

{% extends "layout.html" %}
    {% set active_page = "index" %}

The layout template can then access `active_page`.  Additionally it makes
sense to define a default for that variable::

{% set navigation_bar = [
        ('/', 'index', 'Index'),
        ('/downloads/', 'downloads', 'Downloads'),
        ('/about/', 'about', 'About')
    ] -%}
    {% set active_page = active_page|default('index') -%}
    ...
    <ul id="navigation">
    {% for href, id, caption in navigation_bar %}
      <li{% if id == active_page %} class="active"{% endif
      %}><a href="{{ href|e }}">{{ caption|e }}</a></li>
    {% endfor %}
    </ul>
    ...

.. _accessing-the-parent-loop:

Accessing the parent Loop
-------------------------

The special `loop` variable always points to the innermost loop.  If it's
desired to have access to an outer loop it's possible to alias it::

<table>
    {% for row in table %}
      <tr>
      {% set rowloop = loop %}
      {% for cell in row %}
        <td id="cell-{{ rowloop.index }}-{{ loop.index }}">{{ cell }}</td>
      {% endfor %}
      </tr>
    {% endfor %}
    </table>

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