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 refering to ``models.py`` to infer template names from the models defined therein.
To find a suitable template, Wagtail converts CamelCase names to underscore_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.
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 ``self.``. e.g the page title ``{{ self.title }}`` or another field ``{{ self.author }}``.
Images uploaded to Wagtail by its users (as opposed to a developer's static files, 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 CMS, 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.
In addition to Django's standard tags and filters, Wagtail provides some of its own, which can be ``load``-ed `as you would any other <https://docs.djangoproject.com/en/dev/topics/templates/#custom-tag-and-filter-libraries>`_
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`.
In the above syntax ``[image]`` is the Django object refering to the image. If your page model defined a field called "photo" then ``[image]`` would probably be ``self.photo``. The ``[resize-rule]`` defines how the image is to be resized when inserted into the page; various resizing methods are supported, to cater for different usage cases (e.g. lead images that span the whole width of the page, or thumbnails to be cropped to a fixed size).
The longest edge will be reduced to the equivalent dimension size defined. e.g A portrait image of width 1000, height 2000, treated with the ``max`` dimensions ``1000x500`` (landscape) would result in the image shrunk so the *height* was 500 pixels and the width 250.
This may result in an image slightly **larger** than the dimensions you specify. e.g A square image of width 2000, height 2000, treated with the ``min`` dimensions ``500x200`` (landscape) would have it's height and width changed to 500, i.e matching the width required, but greater than the height.
This can be particularly useful for websites requiring square thumbnails of arbitrary images. For example, a landscape image of width 2000, height 1000, treated with ``fill`` dimensions ``200x200`` would have its height reduced to 200, then its width (ordinarily 400) cropped to 200.
Wagtail does not allow deforming or stretching images. Image dimension ratios will always be kept. Wagtail also *does not support upscaling*. Small images forced to appear at larger sizes will "max out" at their their native dimensions.
In some cases greater control over the ``img`` tag is required, for example to add a custom ``class``. Rather than generating the ``img`` element for you, Wagtail can assign the relevant data to another object using Django's ``as`` syntax:
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.
Wagtail embeds and images are included at their full width, which may overflow the bounds of the content container you've defined in your templates. To make images and embeds responsive -- meaning they'll resize to fit their container -- include the following CSS.
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.
Takes any ``slug`` as defined in a page's "Promote" tab and returns the URL for the matching Page. Like ``pageurl``, will try to provide a relative link if possible, but will default to an absolute link if on a different site. This is most useful when creating shared page furniture e.g top level navigation or site-wide links.
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 local and a live environments.
This tag provides a contextual flyout menu on the top-right of a page for logged-in users. The menu gives editors the ability to edit the current page or add another at the same level. Moderators are also given the ability to accept or reject a page previewed as part of content moderation.
By default the User Bar appears in the top right of the browser window, flush with the edge. If this conflicts with your design it can be moved with a css rule in your own CSS files e.g to move it down from the top:
