.. _writing_templates:

=================
Writing templates
=================

Wagtail uses Django's templating language. For developers new to Django, start with Django's own template documentation:
:doc:`django:topics/templates`

Python programmers new to Django/Wagtail may prefer more technical documentation:
:doc:`ref/templates/api`

You should be familiar with Django templating basics before continuing with this documentation.

Templates
=========

Every type of page or "content type" in Wagtail is defined as a "model" in a file called ``models.py``. If your site has a blog, you might have a ``BlogPage``  model and another called ``BlogPageListing``. The names of the models are up to the Django developer.

For each page model in ``models.py``, Wagtail assumes an HTML template file exists of (almost) the same name. The Front End developer may need to create these templates themselves by referring to ``models.py`` to infer template names from the models defined therein.

To find a suitable template, Wagtail converts CamelCase names to snake_case. So for a ``BlogPage``, a template ``blog_page.html`` will be expected. The name of the template file can be overridden per model if necessary.

Template files are assumed to exist here::

    name_of_project/
        name_of_app/
            templates/
                name_of_app/
                    blog_page.html
            models.py


For more information, see the Django documentation for the :doc:`application directories template loader <ref/templates/api>`.

Page content
~~~~~~~~~~~~

The data/content entered into each page is accessed/output through Django's ``{{ double-brace }}`` notation. Each field from the model must be accessed by prefixing ``page.``. e.g the page title ``{{ page.title }}`` or another field ``{{ page.author }}``.

A custom variable name can be :attr:`configured on the page model <wagtail.core.models.Page.context_object_name>`. If a custom name is defined, ``page`` is still available for use in shared templates.

Additionally ``request.`` is available and contains Django's request object.

Static assets
=============

Static files e.g CSS, JS and images are typically stored here::

    name_of_project/
        name_of_app/
            static/
                name_of_app/
                    css/
                    js/
                    images/
            models.py

(The names "css", "js" etc aren't important, only their position within the tree.)

Any file within the static folder should be inserted into your HTML using the ``{% static %}`` tag. More about it: :ref:`static_tag`.

User images
~~~~~~~~~~~

Images uploaded to a Wagtail site by its users (as opposed to a developer's static files, mentioned above) go into the image library and from there are added to pages via the :doc:`page editor interface </editor_manual/new_pages/inserting_images>`.

Unlike other CMSs, adding images to a page does not involve choosing a "version" of the image to use. Wagtail has no predefined image "formats" or "sizes". Instead the template developer defines image manipulation to occur *on the fly* when the image is requested, via a special syntax within the template.

Images from the library must be requested using this syntax, but a developer's static images can be added via conventional means e.g ``img`` tags. Only images from the library can be manipulated on the fly.

Read more about the image manipulation syntax here :ref:`image_tag`.

.. _template-tags-and-filters:

Template tags & filters
=======================

In addition to Django's standard tags and filters, Wagtail provides some of its own, which can be ``load``-ed :doc:`just like any other <howto/custom-template-tags>`.


Images (tag)
~~~~~~~~~~~~

The ``image`` tag inserts an XHTML-compatible ``img`` element into the page, setting its ``src``, ``width``, ``height`` and ``alt``. See also :ref:`image_tag_alt`.

The syntax for the ``image`` tag is thus:

.. code-block:: html+django

    {% image [image] [resize-rule] %}

For example:

.. code-block:: html+django

    {% load wagtailimages_tags %}
    ...

    {% image page.photo width-400 %}

    <!-- or a square thumbnail: -->
    {% image page.photo fill-80x80 %}


See :ref:`image_tag` for full documentation.


.. _rich-text-filter:

Rich text (filter)
~~~~~~~~~~~~~~~~~~

This filter takes a chunk of HTML content and renders it as safe HTML in the page. Importantly, it also expands internal shorthand references to embedded images, and links made in the Wagtail editor, into fully-baked HTML ready for display.

Only fields using ``RichTextField`` need this applied in the template.

.. code-block:: html+django

    {% load wagtailcore_tags %}
    ...
    {{ page.body|richtext }}


.. _responsive-embeds:

Responsive Embeds
-----------------

As Wagtail does not impose any styling of its own on templates, images and embedded media will be displayed at a fixed width as determined by the HTML. Images can be made to resize to fit their container using a CSS rule such as the following:

.. code-block:: css

    .body img {
        max-width: 100%;
        height: auto;
    }

where ``body`` is a container element in your template surrounding the images.

Making embedded media resizable is also possible, but typically requires custom style rules matching the media's aspect ratio. To assist in this, Wagtail provides built-in support for responsive embeds, which can be enabled by setting ``WAGTAILEMBEDS_RESPONSIVE_HTML = True`` in your project settings. This adds a CSS class of ``responsive-object`` and an inline ``padding-bottom`` style to the embed, to be used in conjunction with the following CSS:

.. code-block:: css

    .responsive-object {
        position: relative;
    }

    .responsive-object iframe,
    .responsive-object object,
    .responsive-object embed {
        position: absolute;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
    }


Internal links (tag)
~~~~~~~~~~~~~~~~~~~~

.. _pageurl_tag:

``pageurl``
-----------

Takes a Page object and returns a relative URL (``/foo/bar/``) if within the same Site as the current page, or absolute (``http://example.com/foo/bar/``) if not.

.. code-block:: html+django

    {% load wagtailcore_tags %}
    ...
    <a href="{% pageurl page.get_parent %}">Back to index</a>


A ``fallback`` keyword argument can be provided - this should be a URL route name that takes no parameters, and will be used as a substitute URL when the passed page is ``None``.

.. code-block:: html+django

    {% load wagtailcore_tags %}

    {% for publication in page.related_publications.all %}
        <li>
            <a href="{% pageurl publication.detail_page fallback='coming_soon' %}">
                {{ publication.title }}
            </a>
        </li>
    {% endfor %}


.. _slugurl_tag:

``slugurl``
------------

Takes any ``slug`` as defined in a page's "Promote" tab and returns the URL for the matching Page. If multiple pages exist with the same slug, the page chosen is undetermined.

Like ``pageurl``, this will try to provide a relative link if possible, but will default to an absolute link if the Page is on a different Site. This is most useful when creating shared page furniture, e.g. top level navigation or site-wide links.

.. code-block:: html+django

    {% load wagtailcore_tags %}
    ...
    <a href="{% slugurl 'news' %}">News index</a>


.. _static_tag:

Static files (tag)
~~~~~~~~~~~~~~~~~~

Used to load anything from your static files directory. Use of this tag avoids rewriting all static paths if hosting arrangements change, as they might between development and live environments.

.. code-block:: html+django

    {% load static %}
    ...
    <img src="{% static "name_of_app/myimage.jpg" %}" alt="My image"/>

Notice that the full path name is not required and the path snippet you enter only need begin with the parent app's directory name.


Multi-site support
~~~~~~~~~~~~~~~~~~

.. _wagtail_site_tag:

``wagtail_site``
----------------

Returns the Site object corresponding to the current request.

.. code-block:: html+django

    {% load wagtailcore_tags %}

    {% wagtail_site as current_site %}

.. _wagtailuserbar_tag:

Wagtail User Bar
================

This tag provides a contextual flyout menu for logged-in users. The menu gives editors the ability to edit the current page or add a child page, besides the options to show the page in the Wagtail page explorer or jump to the Wagtail admin dashboard. Moderators are also given the ability to accept or reject a page being previewed as part of content moderation.

This tag may be used on regular Django views, without page object. The user bar will contain one item pointing to the admin.

.. code-block:: html+django

    {% load wagtailuserbar %}
    ...
    {% wagtailuserbar %}

By default the User Bar appears in the bottom right of the browser window, inset from the edge. If this conflicts with your design it can be moved by passing a parameter to the template tag. These examples show you how to position the userbar in each corner of the screen:

.. code-block:: html+django

    ...
    {% wagtailuserbar 'top-left' %}
    {% wagtailuserbar 'top-right' %}
    {% wagtailuserbar 'bottom-left' %}
    {% wagtailuserbar 'bottom-right' %}
    ...

The userbar can be positioned where it works best with your design. Alternatively, you can position it with a CSS rule in your own CSS files, for example:

.. code-block:: css

    .wagtail-userbar {
         top: 200px !important;
         left: 10px !important;
    }


Varying output between preview and live
=======================================

Sometimes you may wish to vary the template output depending on whether the page is being previewed or viewed live. For example, if you have visitor tracking code such as Google Analytics in place on your site, it's a good idea to leave this out when previewing, so that editor activity doesn't appear in your analytics reports. Wagtail provides a ``request.is_preview`` variable to distinguish between preview and live:

.. code-block:: html+django

    {% if not request.is_preview %}
        <script>
          (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
          ...
        </script>
    {% endif %}
