Using forms in admin views¶
Django’s forms framework can be used within Wagtail admin views just like in any other Django app. However, Wagtail also provides various admin-specific form widgets, such as date/time pickers and choosers for pages, documents, images, and snippets. By constructing forms using wagtail.admin.forms.models.WagtailAdminModelForm
as the base class instead of django.forms.models.ModelForm
, the most appropriate widget will be selected for each model field. For example, given the model and form definition:
from django.db import models
from wagtail.admin.forms.models import WagtailAdminModelForm
from wagtail.images.models import Image
class FeaturedImage(models.Model):
date = models.DateField()
image = models.ForeignKey(Image, on_delete=models.CASCADE)
class FeaturedImageForm(WagtailAdminModelForm):
class Meta:
model = FeaturedImage
the date
and image
fields on the form will use a date picker and image chooser widget respectively.
Defining admin form widgets¶
If you have implemented a form widget of your own, you can configure WagtailAdminModelForm
to select it for a given model field type. This is done by calling the wagtail.admin.forms.models.register_form_field_override
function, typically in an AppConfig.ready
method.
- register_form_field_override(model_field_class, to=None, override=None, exact_class=False)¶
Specify a set of options that will override the form field’s defaults when
WagtailAdminModelForm
encounters a given model field type.- Parameters:
model_field_class – Specifies a model field class, such as
models.CharField
; the override will take effect on fields that are instances of this class.to – For
ForeignKey
fields, indicates the model that the field must point to for the override to take effect.override – A dict of keyword arguments to be passed to the form field’s
__init__
method, such aswidget
.exact_class – If true, the override will only take effect for model fields that are of the exact type given by
model_field_class
, and not a subclass of it.
For example, if the app wagtail.videos
implements a Video
model and a VideoChooser
form widget, the following AppConfig definition will ensure that WagtailAdminModelForm
selects VideoChooser
as the form widget for any foreign keys pointing to Video
:
from django.apps import AppConfig
from django.db.models import ForeignKey
class WagtailVideosAppConfig(AppConfig):
name = 'wagtail.videos'
label = 'wagtailvideos'
def ready(self):
from wagtail.admin.forms.models import register_form_field_override
from .models import Video
from .widgets import VideoChooser
register_form_field_override(ForeignKey, to=Video, override={'widget': VideoChooser})
Wagtail’s edit views for pages and snippets use WagtailAdminModelForm
as standard, so this change will take effect across the Wagtail admin; a foreign key to Video
on a page model will automatically use the VideoChooser
widget, with no need to specify this explicitly.
Panels¶
Panels (also known as edit handlers until Wagtail 3.0) are Wagtail’s mechanism for specifying the content and layout of a model form without having to write a template. They are used for the editing interface for pages and snippets, as well as the site settings contrib module.
See Panel types for the set of panel types provided by Wagtail. All panels inherit from the base class wagtail.admin.panels.Panel
. A single panel object (usually ObjectList
or TabbedInterface
) exists at the top level and is the only one directly accessed by the view code; panels containing child panels inherit from the base class wagtail.admin.panels.PanelGroup
and take care of recursively calling methods on their child panels where appropriate.
A view performs the following steps to render a model form through the panels mechanism:
The top-level panel object for the model is retrieved. Usually, this is done by looking up the model’s
edit_handler
property and falling back on anObjectList
consisting of children given by the model’spanels
property. However, it may come from elsewhere - for example, snippets can define their panels via theSnippetViewSet
class.If the
PanelsGroup
s permissions do not allow a user to see this panel, then nothing more will be done.This can be modified using the
permission
keyword argument, see examples of this usage in Customizing the tabbed interface and Permissions.
The view calls
bind_to_model
on the top-level panel, passing the model class, and this returns a clone of the panel with amodel
property. As part of this process, theon_model_bound
method is invoked on each child panel, to allow it to perform additional initialization that requires access to the model (for example, this is whereFieldPanel
retrieves the model field definition).The view then calls
get_form_class
on the top-level panel to retrieve a ModelForm subclass that can be used to edit the model. This proceeds as follows:Retrieve a base form class from the model’s
base_form_class
property, falling back onwagtail.admin.forms.WagtailAdminModelForm
Call
get_form_options
on each child panel - which returns a dictionary of properties includingfields
andwidgets
- and merge the results into a single dictionaryConstruct a subclass of the base form class, with the options dict forming the attributes of the inner
Meta
class.
An instance of the form class is created as per a normal Django form view.
The view then calls
get_bound_panel
on the top-level panel, passinginstance
,form
andrequest
as keyword arguments. This returns aBoundPanel
object, which follows the template component API. Finally, theBoundPanel
object (and its media definition) is rendered onto the template.
New panel types can be defined by subclassing wagtail.admin.panels.Panel
- see Panel API.