How to extend existing plugins¶
Existing plugins can be extended through two type of class mixins.
djangocms-frontend looks for these mixins in two places:
In the theme module. Its name is specified by the setting
DJANGOCMS_FRONTEND_THEMEand defaults todjangocms_frontend. For a theme app calledthemeand the bootstrap5 framework this would betheme.frontends.bootstrap5.py.In
djangocms_frontend.contrib.*app*.frontends.*framework*.py. For the alert app and the bootstrap5 framework this would bedjangocms_frontend.contrib.alert.frontends.bootstrap5.py.
Both mixins are included if they exist and all methods have to call the super methods to ensure all form extensions and render functionalities are processed.
The theme module is primarily thought to allow for third party extensions in terms of functionality and/or design.
The framework module is primarily thought to allow for adaptation of
djangocms-frontend to other css frameworks besides Bootstrap 5.
RenderMixins¶
The render mixins are called “*PluginName*RenderMixin”, e.g.
AlertRenderMixin and are applied to the plugin class. This allows
for the redefinition of the CMSPlugin.render method, especially to
prepare the context for rendering.
Also it can add fields to the front end editing form by subclassing
CMSPlugin.get_fieldsets. This allows for extension or change of the
plugin’s admin form. The admin form is used to edit or create a plugin.
FormMixins¶
Form mixins are used to add fields to a plugin’s admin form. These fields are available to the render mixins and, of course, to the plugin templates.
Form mixins are called “*PluginName*FormMixin”, e.g. AlertFormMixin and are
applied to the editing form class. Form mixins are a subclass of
entangled.EntangledModelFormMixin.
Working example¶
Let’s say you wanted to extend the GridContainerPlugin to offer the
option for a background image, and say a blur effect. The way to do it
is to create a theme app. You are free to chose its name. For this example
we take it to be “theme”. Please replace “theme” by your own theme’s name.
First, create a directory structure like this:
theme
├── __init__.py
├── forms.py
├── frameworks
│ ├── __init__.py
│ └── bootstrap5.py
├── static
│ └── css
│ └── background_image.css
└── templates
└── djangocms_frontend
└── bootstrap5
└── grid_container.html
All __init__.py files remain empty.
Next, you add some fields to the GridContainerForm (in
theme/forms.py):
from django import forms
from django.db.models import ManyToOneRel
from django.utils.translation import gettext as _
from djangocms_frontend import settings
from entangled.forms import EntangledModelFormMixin
from filer.fields.image import AdminImageFormField, FilerImageField
from filer.models import Image
IMAGE_POSITIONING = (
("center center", _("Fully Centered")),
("left top", _("Top left")),
("center top", _("Top center")),
("right top", _("Top right")),
("left center", _("Center left")),
("right center", _("Center right")),
("left bottom", _("Bottom left")),
("center bottom", _("Bottom center")),
("right bottom", _("Bottom right")),
)
class GridContainerFormMixin(EntangledModelFormMixin):
class Meta:
entangled_fields = {
"config": [
"container_image",
"image_position",
"container_blur",
]
}
container_image = AdminImageFormField(
rel=ManyToOneRel(FilerImageField, Image, "id"),
queryset=Image.objects.all(),
to_field_name="id",
label=_("Image"),
required=False,
help_text=_("If provided used as a cover for container."),
)
image_position = forms.ChoiceField(
required=False,
choices=settings.EMPTY_CHOICE + IMAGE_POSITIONING,
initial="",
label=_("Background image position"),
)
container_blur = forms.IntegerField(
required=False,
initial=0,
min_value=0,
max_value=10,
help_text=_("Blur of container image (in px)."),
)
Warning
These form fields are mixed to the original form. Please make sure to avoid name collisions for the fields.
Note
If you need to add many form mixins, consider turning forms.py into a
package, i.e. create a directory forms and distribute the mixins over
several files, e.g., forms/marketing_forms.py etc., and importing the
all mixins relevant to djangocms-frontend into the directory’s
__init__.py.
Rendering should be done with the Bootstrap 5 framework. Hence all rendering
mixins go into theme/bootstrap5.py. Since we are extending the
GridContainer plugin the appropriate mixin to define is
GridContainerMixin:
from django.utils.translation import gettext as _
from djangocms_frontend.helpers import insert_fields
class GridContainerRenderMixin:
render_template = "djangocms_frontend/bootstrap5/grid_container.html"
def get_fieldsets(self, request, obj=None):
"""Extend the fieldset of the plugin to contain the new fields
defined in forms.py"""
return insert_fields(
super().get_fieldsets(request, obj),
(
"container_image",
(
"image_position",
"container_blur",
),
),
block=None, # Create a new fieldset (called block here)
position=1, # at position 1 (i.e. directly after the mail fieldset)
blockname=_("Image"), # and call the fieldset "Image"
)
def render(self, context, instance, placeholder):
"""Render should process the form fields and turn them into appropriate
context items or add corresponding classes to the instance"""
if getattr(instance, "container_image", None):
instance.add_classes("imagecontainer")
context["bg_color"] = (
f"bg-{instance.background_context}"
if getattr(instance, "background_context", False)
else ""
)
return super().render(context, instance, placeholder)
Warning
Do not forget to call super() in both the get_fieldsets and the
render method.
The render method provides required context data for the extended
functionality. In this case it adds imagecontainer to the list of
classes for the container, processes the background colors since it should
appear above the image (and not below), as well as blur.
The get_fieldsets method is used to make django CMS show the new
form fields in the plugin’s edit modal (admin form, technically
speaking).
Then, a new template is needed (in
theme/templates/djangocms_frontend/bootstrap5/grid_container.html):
{% load cms_tags sekizai_tags static %}{% spaceless %}
<{{ instance.tag_type }}{{ instance.get_attributes }}
{% if instance.background_opacity and not instance.image %}
{% if instance.container_blur %}
backdrop-filter: blur({{ instance.container_blur }}px);
{% endif %}"
{% endif %}>
{% if instance.image %}
<div class="image"
style="background-image: url('{{ instance.image.url }}');
background-position: {{ instance.image_position|default:'center center' }};
background-repeat: no-repeat;background-size: cover;
{% if instance.container_blur %}
filter: blur({{ instance.container_blur }}px);
{% endif %}">
</div>
{% elif instance.container_image %}
<div class="image placeholder placeholder-wave"></div>
{% endif %}
{% if bg_color %}
<div class="cover {{ bg_color }}"{% if instance.background_opacity %}
style="opacity: {{ instance.background_opacity }}%"{% endif %}></div>
{% endif %}
{% if instance.container_image %}
<div class="content">
{% endif %}
{% for plugin in instance.child_plugin_instances %}
{% render_plugin plugin %}
{% endfor %}
{% if instance.container_image %}</div>{% endif %}
</{{ instance.tag_type }}>{% endspaceless %}
{# Only add if the css is not included in your site's global css #}
{% addtoblock 'css' %}
<link rel="stylesheet" href="{% static 'css/background_image.css' %}">
{% endaddtoblock %}
Finally, a set of css style complement the new template. The styles can either be added to the css block in the template (if used scarcely and as done in the above example) or directly to your project’s css files.
The required styles are:
/* Image Container */
div.imagecontainer {
position: relative;
min-height: 112px;
}
div.imagecontainer > div.cover,
div.imagecontainer > div.image {
position: absolute;
left:0;
right:0;
top:0;
bottom:0;
}
div.imagecontainer > div.content {
position: relative;
}
With these three additions, all grid container plugins will now have additional fields to define background images to cover the container area.
If the theme is taken out of the path djangocms-frontend will fall back to its basic functionality, i.e. the background images will not be shown. As long as plugins are not edited the background image information will be preserved.
Note
A few suggestions on extending djangocms-frontend:
You may think of customizing bootstrap by including a folder
sassin your theme app. For more see Bootstrap 5 documentation on customizing.If you need entirely new plugins, create a file
cms_plugins.pyand importCMSUIPlugin(import fromdjangocms_frontend.cms_plugins) as base class for the plugins.Create
models.pyfile for the models (which need to be proxy models ofFrontendUIItem(import fromdjangocms_frontend.models).