All Cascade plugins are derived from the same base class CascadeModelBase
, which stores all its model fields inside a dictionary, serialized as JSON string in the database. This makes it much easier to extend the Cascade eco-system, since no database migration is required when adding a new, or extending plugins from this project.
The database model CascadeModelBase
stores all the plugin settings in a single JSON field named glossary
. This in practice behaves like a Django context, but in order to avoid confusion with the latter, it has been named “glossary”.
This plugin is very simple and just renders static content which has been declared in the template.
from cms.plugin_pool import plugin_pool
from cmsplugin_cascade.plugin_base import CascadePluginBase
class StylishPlugin(CascadePluginBase):
name = 'Stylish Element'
render_template = 'myapp/cascade/stylish-element.html'
plugin_pool.register_plugin(StylishPlugin)
If the editor form pops up for this plugin, a dumb message appears: “There are no further settings for this plugin”. This is because no editable fields have been added to that plugin yet.
In order to make the plugin remember its settings and other optional data, the programmer must add a list of special form fields to its plugin. These fields then are used to auto-generate the editor for this DjangoCMS plugin.
Each of those form fields handle a special field value, or in some cases, a list of field values. They all require a widget, which is used when rendering the editors form.
Lets add a simple selector to choose between a red and a green color. Do this by adding a PartialFormField
to a member list named glossary_fields
.
from django.forms import widgets
from cmsplugin_cascade.plugin_base import CascadePluginBase, PartialFormField
class StylishPlugin(CascadePluginBase):
...
glossary_fields = (
PartialFormField('color',
widgets.Select(choices=(('red', 'Red'), ('green', 'Green'),)),
label="Element's Color",
initial='red',
help_text="Specify the color of the DOM element."
),
# more PartialFormField objects
)
In the plugin's editor, the form now pops up with a single select box, where the user can choose between a red and a green element.
A PartialFormField
accepts five arguments:
- The name of the field. It must be unique in the given list of
glossary_fields
. - The widget. This can be a built-in Django widget or any valid widget derived from it.
- The
label
used to describe the field. If omitted, thename
of the partial form field is used. - An optional
initial
value to be used with Radio- or Select fields. - An optional
help_text
to describe the field's purpose.
For single text fields or select boxes, Django's built-in widgets, such as widgets.TextInput
or widgets.RadioSelect
can be used. Sometimes these simple widgets are not enough, therefore some special input widgets have been prepared to be used with DjangoCMS-Cascade. They are all part of the module cmsplugin_cascade.widgets
.
- MultipleTextInputWidget
Use this widget to group a list of text input fields together. This for instance is used, to encapsulate all inline styles into one JSON object.
- NumberInputWidget
The same as Django's
TextInput
-widget, but doing field validation. This checks if the entered input data is a valid number.- MultipleInlineStylesWidget
The same as the
MultipleTextInputWidget
, but doing field validation. This checks if the entered input data ends withpx
orem
.
For the plugin editor, djangocms-cascade automatically creates a form for each PartialFormField
in the list of glossary_fields
. Sometimes however, you might need more control over the fields displayed in the editor, versus the fields stored inside the glossary
.
Similar to the Django's admin.ModelAdmin
, this can be achieved by overriding the plugins form element. Such a customized form can add as many fields as required, while the controlled glossary contains a compact summary.
To override the plugins form, add a member form
to your plugin. This member variable shall refer to a customized form derived from forms.models.ModelForm
. For further details about how to use this feature, refer to the supplied implementations.
Since all djangocms-cascade plugins store their data in a JSON-serializable field, there rarely is a need to add another database field to the common models CascadeElement
and/or SharableCascadeElement
and thus no need for database migrations.
However, quite often there is a need to add or override the methods for these models. Therefore each Cascade plugin creates its own proxy model on the fly. These models are derived from CascadeElement
and/or SharableCascadeElement
and named like the plugin class, with the suffix Model
. By default, their behavior is the same as for their parent model classes.
To extend this behavior, the author of a plugin may declare a tuple of mixin classes, which are injected during the creation of the proxy model. Example:
class MySpecialPropertyMixin(object):
def processed_value(self):
value = self.glossary.get('field_name')
# process value
return value
class MySpecialPlugin(LinkPluginBase):
module = 'My Module'
name = 'My special Plugin'
model_mixins = (MySpecialPropertyMixin,)
render_template = 'my_module/my_special_plugin.html'
glossary_fields = (
PartialFormField('field_name',
widgets.TextInput(),
),
# other partial form fields
)
...
The proxy model created for this plugin class, now contains the extra method content()
, which for instance may be accessed during template rendering.
templates/my_module/my_special_plugin.html
:
<div>{{ instance.processed_value }}</div>
Needless to say, that you can't add any extra database fields to the class named MySpecialPropertyMixin
, since the corresponding model class is marked as proxy.
CascadePluginBase
is derived from CMSPluginBase
, so all CMSPluginBase attributes can also be overridden by plugins derived from CascadePluginBase
. Please refer to their documentation for details.
Additionally BootstrapPluginBase
allows the following attributes:
- name
This name is shown in the pull down menu in structure view. There is not default value.
- tag_type
A HTML element into which this plugin is wrapped. Generic templates can render their content into any ``tag_type. Specialized rendering templates usually have a hard coded tag type, then this attribute can be omitted.
- require_parent
Default:
True
. This differs fromCMSPluginBase
.Is it required that this plugin is a child of another plugin? Otherwise the plugin can be added to any placeholder.
- parent_classes
Default: None.
A list of Plugin Class Names. If this is set, the plugin may only be added to plugins listed here.
- allow_children
Default:
True
. This differs fromCMSPluginBase
.Can this plugin have child plugins? Or can other plugins be placed inside this plugin?
- child_classes
Default: A list of plugins, which are allowed as children of this plugin. This differs from
CMSPluginBase
, where this attribute is None.Do not override this attribute. DjangoCMS-Cascade automatically generates a list of allowed children plugins, by evaluating the list
parent_classes
from the other plugins in the pool.Plugins, which are part of the plugin pool, but which do not specify their parents using the list
parent_classes
, may be added as children to the current plugin by adding them to the attributegeneric_child_classes
.- generic_child_classes
Default: None.
A list of plugins which shall be added as children to a plugin, but which themselves do not declare this plugin in their
parent_classes
.- glossary_fields
Default: None
A list of
PartialFormField
's. See the documentation above for details.- default_css_class
Default: None.
A CSS class which is always added to the wrapping DOM element.
- default_inline_styles
Default: None.
A dictionary of inline styles, which is always added to the wrapping DOM element.
- get_identifier
This is a classmethod, which can be added to a plugin to give it a meaningful name.
Its signature is:
@classmethod def get_identifier(cls, obj): return 'A plugin name'
This method shall be used to name the plugin in structured view.
- form
Override the form used by the plugin editor. This must be a class derived from
forms.models.ModelForm
.- model_mixins
Tuple of mixin classes, with additional methods to be added the auto-generated proxy model for the given plugin class.
Check section “Overriding the Model” for a detailed explanation.