path: root/docs/themes.rst

.. _theming-pelican:

Creating themes
###############

To generate its HTML output, Pelican uses the `Jinja <http://jinja.pocoo.org/>`_
templating engine due to its flexibility and straightforward syntax. If you want
to create your own theme, feel free to take inspiration from the `"simple" theme
<https://github.com/getpelican/pelican/tree/master/pelican/themes/simple/templates>`_.

To generate your site using a theme you have created (or downloaded manually and
then modified), you can specify that theme via the ``-t`` flag::

    pelican content -s pelicanconf.py -t /projects/your-site/themes/your-theme

If you'd rather not specify the theme on every invocation, you can define
``THEME`` in your settings to point to the location of your preferred theme.


Structure
=========

To make your own theme, you must follow the following structure::

    ├── static
    │   ├── css
    │   └── images
    └── templates
        ├── archives.html         // to display archives
        ├── period_archives.html  // to display time-period archives
        ├── article.html          // processed for each article
        ├── author.html           // processed for each author
        ├── authors.html          // must list all the authors
        ├── categories.html       // must list all the categories
        ├── category.html         // processed for each category
        ├── index.html            // the index (list all the articles)
        ├── page.html             // processed for each page
        ├── tag.html              // processed for each tag
        └── tags.html             // must list all the tags. Can be a tag cloud.

* `static` contains all the static assets, which will be copied to the output
  `theme` folder. The above filesystem layout includes CSS and image folders,
  but those are just examples. Put what you need here.

* `templates` contains all the templates that will be used to generate the content.
  The template files listed above are mandatory; you can add your own templates
  if it helps you keep things organized while creating your theme.


Templates and variables
=======================

The idea is to use a simple syntax that you can embed into your HTML pages.
This document describes which templates should exist in a theme, and which
variables will be passed to each template at generation time.

All templates will receive the variables defined in your settings file, as long
as they are in all-caps. You can access them directly.


Common variables
----------------

All of these settings will be available to all templates.

=============   ===================================================
Variable        Description
=============   ===================================================
output_file     The name of the file currently being generated. For
                instance, when Pelican is rendering the home page,
                output_file will be "index.html".
articles        The list of articles, ordered descending by date.
                All the elements are `Article` objects, so you can
                access their attributes (e.g. title, summary, author
                etc.). Sometimes this is shadowed (for instance in
                the tags page). You will then find info about it
                in the `all_articles` variable.
dates           The same list of articles, but ordered by date,
                ascending.
tags            A list of (tag, articles) tuples, containing all
                the tags.
categories      A list of (category, articles) tuples, containing
                all the categories and corresponding articles (values)
pages           The list of pages
=============   ===================================================


Sorting
-------

URL wrappers (currently categories, tags, and authors), have
comparison methods that allow them to be easily sorted by name::

    {% for tag, articles in tags|sort %}

If you want to sort based on different criteria, `Jinja's sort
command`__ has a number of options.

__ http://jinja.pocoo.org/docs/templates/#sort


Date Formatting
---------------

Pelican formats the date according to your settings and locale
(``DATE_FORMATS``/``DEFAULT_DATE_FORMAT``) and provides a
``locale_date`` attribute. On the other hand, the ``date`` attribute will
be a `datetime`_ object. If you need custom formatting for a date
different than your settings, use the Jinja filter ``strftime``
that comes with Pelican. Usage is same as Python `strftime`_ format,
but the filter will do the right thing and format your date according
to the locale given in your settings::

    {{ article.date|strftime('%d %B %Y') }}

.. _datetime: http://docs.python.org/2/library/datetime.html#datetime-objects
.. _strftime: http://docs.python.org/2/library/datetime.html#strftime-strptime-behavior


index.html
----------

This is the home page or index of your blog, generated at ``index.html``.

If pagination is active, subsequent pages will reside in ``index{number}.html``.

======================  ===================================================
Variable                Description
======================  ===================================================
articles_paginator      A paginator object for the list of articles
articles_page           The current page of articles
articles_previous_page  The previous page of articles (``None`` if page does
                        not exist)
articles_next_page      The next page of articles (``None`` if page does
                        not exist)
dates_paginator         A paginator object for the article list, ordered by
                        date, ascending.
dates_page              The current page of articles, ordered by date,
                        ascending.
dates_previous_page     The previous page of articles, ordered by date,
                        ascending (``None`` if page does not exist)
dates_next_page         The next page of articles, ordered by date,
                        ascending (``None`` if page does not exist)
page_name               'index' -- useful for pagination links
======================  ===================================================


author.html
-------------

This template will be processed for each of the existing authors, with
output generated according to the ``AUTHOR_SAVE_AS`` setting (`Default:`
``author/{author_name}.html``). If pagination is active, subsequent pages will by
default reside at ``author/{author_name}{number}.html``.

======================  ===================================================
Variable                Description
======================  ===================================================
author                  The name of the author being processed
articles                Articles by this author
dates                   Articles by this author, but ordered by date,
                        ascending
articles_paginator      A paginator object for the list of articles
articles_page           The current page of articles
articles_previous_page  The previous page of articles (``None`` if page does
                        not exist)
articles_next_page      The next page of articles (``None`` if page does
                        not exist)
dates_paginator         A paginator object for the article list, ordered by
                        date, ascending.
dates_page              The current page of articles, ordered by date,
                        ascending.
dates_previous_page     The previous page of articles, ordered by date,
                        ascending (``None`` if page does not exist)
dates_next_page         The next page of articles, ordered by date,
                        ascending (``None`` if page does not exist)
page_name               AUTHOR_URL where everything after `{slug}` is
                        removed -- useful for pagination links
======================  ===================================================


category.html
-------------

This template will be processed for each of the existing categories, with
output generated according to the ``CATEGORY_SAVE_AS`` setting (`Default:`
``category/{category_name}.html``). If pagination is active, subsequent pages will by
default reside at ``category/{category_name}{number}.html``.

======================  ===================================================
Variable                Description
======================  ===================================================
category                The name of the category being processed
articles                Articles for this category
dates                   Articles for this category, but ordered by date,
                        ascending
articles_paginator      A paginator object for the list of articles
articles_page           The current page of articles
articles_previous_page  The previous page of articles (``None`` if page does
                        not exist)
articles_next_page      The next page of articles (``None`` if page does
                        not exist)
dates_paginator         A paginator object for the list of articles,
                        ordered by date, ascending
dates_page              The current page of articles, ordered by date,
                        ascending
dates_previous_page     The previous page of articles, ordered by date,
                        ascending (``None`` if page does not exist)
dates_next_page         The next page of articles, ordered by date,
                        ascending (``None`` if page does not exist)
page_name               CATEGORY_URL where everything after `{slug}` is
                        removed -- useful for pagination links
======================  ===================================================


article.html
-------------

This template will be processed for each article, with
output generated according to the ``ARTICLE_SAVE_AS`` setting (`Default:`
``{article_name}.html``). The following variables are available when
rendering.

=============   ===================================================
Variable        Description
=============   ===================================================
article         The article object to be displayed
category        The name of the category for the current article
=============   ===================================================

Any metadata that you put in the header of the article source file
will be available as fields on the ``article`` object. The field name will be
the same as the name of the metadata field, except in all-lowercase characters.

For example, you could add a field called `FacebookImage` to your article
metadata, as shown below:

.. code-block:: markdown

    Title: I love Python more than music
    Date: 2013-11-06 10:06
    Tags: personal, python
    Category: Tech
    Slug: python-je-l-aime-a-mourir
    Author: Francis Cabrel
    FacebookImage: http://franciscabrel.com/images/pythonlove.png

This new metadata will be made available as `article.facebookimage` in your
`article.html` template. This would allow you, for example, to specify an
image for the Facebook open graph tags that will change for each article:

.. code-block:: html+jinja

    <meta property="og:image" content="{{ article.facebookimage }}"/>


page.html
---------

This template will be processed for each page, with
output generated according to the ``PAGE_SAVE_AS`` setting (`Default:`
``pages/{page_name}.html``). The following variables are available when
rendering.

=============   ===================================================
Variable        Description
=============   ===================================================
page            The page object to be displayed. You can access its
                title, slug, and content.
=============   ===================================================


tag.html
--------

This template will be processed for each tag, with
output generated according to the ``TAG_SAVE_AS`` setting (`Default:`
``tag/{tag_name}.html``). If pagination is active, subsequent pages will by
default reside at ``tag/{tag_name}{number}.html``.

======================  ===================================================
Variable                Description
======================  ===================================================
tag                     The name of the tag being processed
articles                Articles related to this tag
dates                   Articles related to this tag, but ordered by date,
                        ascending
articles_paginator      A paginator object for the list of articles
articles_page           The current page of articles
articles_previous_page  The previous page of articles (``None`` if page does
                        not exist)
articles_next_page      The next page of articles (``None`` if page does
                        not exist)
dates_paginator         A paginator object for the list of articles,
                        ordered by date, ascending
dates_page              The current page of articles, ordered by date,
                        ascending
dates_previous_page     The previous page of articles, ordered by date,
                        ascending (``None`` if page does not exist)
dates_next_page         The next page of articles, ordered by date,
                        ascending (``None`` if page does not exist)
page_name               TAG_URL where everything after `{slug}` is removed
                        -- useful for pagination links
======================  ===================================================


period_archives.html
--------------------

This template will be processed for each year of your posts if a path
for ``YEAR_ARCHIVE_SAVE_AS`` is defined, each month if ``MONTH_ARCHIVE_SAVE_AS``
is defined, and each day if ``DAY_ARCHIVE_SAVE_AS`` is defined.

===================     ===================================================
Variable                Description
===================     ===================================================
period                  A tuple of the form (`year`, `month`, `day`) that
                        indicates the current time period. `year` and `day`
                        are numbers while `month` is a string. This tuple
                        only contains `year` if the time period is a
                        given year. It contains both `year` and `month`
                        if the time period is over years and months and
                        so on.

===================     ===================================================

You can see an example of how to use `period` in the `"simple" theme
<https://github.com/getpelican/pelican/blob/master/pelican/themes/simple/templates/period_archives.html>`_.


Feeds
=====

The feed variables changed in 3.0. Each variable now explicitly lists ATOM or
RSS in the name. ATOM is still the default. Old themes will need to be updated.
Here is a complete list of the feed variables::

    FEED_ATOM
    FEED_RSS
    FEED_ALL_ATOM
    FEED_ALL_RSS
    CATEGORY_FEED_ATOM
    CATEGORY_FEED_RSS
    TAG_FEED_ATOM
    TAG_FEED_RSS
    TRANSLATION_FEED_ATOM
    TRANSLATION_FEED_RSS

.. _theme_inheritance:

Theme inheritance
=================

Since version 3.6, Pelican supports both implicit and explicit
inheritance from any theme specified in the ``THEMES`` setting. By
default the special ``simple`` theme is inherited both implicitly and
explicitly, so you can re-use its theme templates in your own themes.

Implicit Inheritance
--------------------

If one of the mandatory files in the ``templates/`` directory of your
theme is missing, it will be replaced by a matching template from any
of the implicitly inherited themes.  So if the HTML structure of a
template in the by default inherited ``simple`` theme is right for you,
you don't have to write a new template from scratch.

Explicit Inheritance
--------------------

You explicitly extend templates from explicitly inherited themes in
your own themes by using the ``{% extends %}`` directive as in the
following example:

With the following ``THEMES`` setting which is the default plus an
extra explicitly inherited theme

.. code-block:: python

    THEMES = ['simple', ['!simple', 'simple'], ['!foo', 'foo']]

You can extend parent (inherited) or sibling (your own theme) templates

.. code-block:: html+jinja

    {% extends "!simple/index.html" %}   <!-- extends the ``index.html`` template from the ``simple`` theme -->

    {% extends "!foo/index.html" %}   <!-- extends the ``index.html`` template from the ``foo`` theme -->

    {% extends "index.html" %}   <!-- "regular" extending, either finds a sibling template or one in an implicitly inherited theme -->


Example
-------

With this system, it is possible to create a theme with just two files.

base.html
"""""""""

The first file is the ``templates/base.html`` template:

.. code-block:: html+jinja

    {% extends "!simple/base.html" %}

    {% block head %}
    {{ super() }}
       <link rel="stylesheet" type="text/css" href="{{ SITEURL }}/theme/css/style.css" />
    {% endblock %}

1. On the first line, we extend the ``base.html`` template from the ``simple``
   theme, so we don't have to rewrite the entire file.
2. On the third line, we open the ``head`` block which has already been defined
   in the ``simple`` theme.
3. On the fourth line, the function ``super()`` keeps the content previously
   inserted in the ``head`` block.
4. On the fifth line, we append a stylesheet to the page.
5. On the last line, we close the ``head`` block.

This file will be extended by all the other templates, so the stylesheet will
be linked from all pages.

style.css
"""""""""

The second file is the ``static/css/style.css`` CSS stylesheet:

.. code-block:: css

    body {
        font-family : monospace ;
        font-size : 100% ;
        background-color : white ;
        color : #111 ;
        width : 80% ;
        min-width : 400px ;
        min-height : 200px ;
        padding : 1em ;
        margin : 5% 10% ;
        border : thin solid gray ;
        border-radius : 5px ;
        display : block ;
    }

    a:link    { color : blue ; text-decoration : none ;      }
    a:hover   { color : blue ; text-decoration : underline ; }
    a:visited { color : blue ;                               }

    h1 a { color : inherit !important }
    h2 a { color : inherit !important }
    h3 a { color : inherit !important }
    h4 a { color : inherit !important }
    h5 a { color : inherit !important }
    h6 a { color : inherit !important }

    pre {
        margin : 2em 1em 2em 4em ;
    }

    #menu li {
        display : inline ;
    }

    #post-list {
        margin-bottom : 1em ;
        margin-top : 1em ;
    }

Download
""""""""

You can download this example theme :download:`here <_static/theme-basic.zip>`.