11 KiB
Generic views
Wagtail provides several generic views for handling common tasks such as creating / editing model instances and chooser modals. Since these often involve several related views with shared properties (such as the model that we're working with, and its associated icon) Wagtail also implements the concept of a viewset, which allows a bundle of views to be defined collectively, and their URLs to be registered with the admin app as a single operation through the register_admin_viewset hook.
ModelViewSet
The wagtail.admin.viewsets.model.ModelViewSet class provides the views for listing, creating, editing, and deleting model instances. For example, if we have the following model:
from django.db import models
class Person(models.Model):
first_name = models.CharField(max_length=255)
last_name = models.CharField(max_length=255)
def __str__(self):
return "%s %s" % (self.first_name, self.last_name)
The following definition (to be placed in the same app's views.py) will generate a set of views for managing Person instances:
from wagtail.admin.viewsets.model import ModelViewSet
from .models import Person
class PersonViewSet(ModelViewSet):
model = Person
form_fields = ["first_name", "last_name"]
icon = "user"
person_viewset = PersonViewSet("person") # defines /admin/person/ as the base URL
This viewset can then be registered with the Wagtail admin to make it available under the URL /admin/person/, by adding the following to wagtail_hooks.py:
from wagtail import hooks
from .views import person_viewset
@hooks.register("register_admin_viewset")
def register_viewset():
return person_viewset
Various additional attributes are available to customise the viewset - see .
ChooserViewSet
The wagtail.admin.viewsets.chooser.ChooserViewSet class provides the views that make up a modal chooser interface, allowing users to select from a list of model instances to populate a ForeignKey field. Using the same Person model, the following definition (to be placed in views.py) will generate the views for a person chooser modal:
from wagtail.admin.viewsets.chooser import ChooserViewSet
class PersonChooserViewSet(ChooserViewSet):
# The model can be specified as either the model class or an "app_label.model_name" string;
# using a string avoids circular imports when accessing the StreamField block class (see below)
model = "myapp.Person"
icon = "user"
choose_one_text = "Choose a person"
choose_another_text = "Choose another person"
edit_item_text = "Edit this person"
form_fields = ["first_name", "last_name"] # fields to show in the "Create" tab
person_chooser_viewset = PersonChooserViewSet("person_chooser")
Again this can be registered with the register_admin_viewset hook:
from wagtail import hooks
from .views import person_chooser_viewset
@hooks.register("register_admin_viewset")
def register_viewset():
return person_chooser_viewset
Registering a chooser viewset will also set up a chooser widget to be used whenever a ForeignKey field to that model appears in a WagtailAdminModelForm - see . In particular, this means that a panel definition such as FieldPanel("author"), where author is a foreign key to the Person model, will automatically use this chooser interface. The chooser widget class can also be retrieved directly (for use in ordinary Django forms, for example) as the widget_class property on the viewset. For example, placing the following code in widgets.py will make the chooser widget available to be imported with from myapp.widgets import PersonChooserWidget:
from .views import person_chooser_viewset
PersonChooserWidget = person_chooser_viewset.widget_class
The viewset also makes a StreamField chooser block class available, through the method get_block_class. Placing the following code in blocks.py will make a chooser block available for use in StreamField definitions by importing from myapp.blocks import PersonChooserBlock:
from .views import person_chooser_viewset
PersonChooserBlock = person_chooser_viewset.get_block_class(
name="PersonChooserBlock", module_path="myapp.blocks"
)
Chooser viewsets for non-model datasources
While the generic chooser views are primarily designed to use Django models as the data source, choosers based on other sources such as REST API endpoints can be implemented by overriding the individual methods that deal with data retrieval.
Within wagtail.admin.views.generic.chooser:
BaseChooseView.get_object_list()- returns a list of records to be displayed in the chooser. (In the default implementation, this is a Django QuerySet, and the records are model instances.)BaseChooseView.columns- a list ofwagtail.admin.ui.tables.Columnobjects specifying the fields of the record to display in the final tableBaseChooseView.apply_object_list_ordering(objects)- given a list of records as returned fromget_object_list, returns the list with the desired ordering appliedChosenViewMixin.get_object(pk)- returns the record identified by the given primary keyChosenResponseMixin.get_chosen_response_data(item)- given a record, returns the dictionary of data that will be passed back to the chooser widget to populate it (consisting of itemsidandtitle, unless the chooser widget's JavaScript has been customised)
Within wagtail.admin.widgets:
BaseChooser.get_instance(value)- given a value that may be a record, a primary key, or None, returns the corresponding record or NoneBaseChooser.get_value_data_from_instance(item)- given a record, returns the dictionary of data that will populate the chooser widget (consisting of itemsidandtitle, unless the widget's JavaScript has been customised)
For example, the following code will implement a chooser that runs against a JSON endpoint for the User model at http://localhost:8000/api/users/, set up with Django REST Framework using the default configuration and no pagination:
from django.views.generic.base import View
import requests
from wagtail.admin.ui.tables import Column, TitleColumn
from wagtail.admin.views.generic.chooser import (
BaseChooseView, ChooseViewMixin, ChooseResultsViewMixin, ChosenResponseMixin, ChosenViewMixin, CreationFormMixin
)
from wagtail.admin.viewsets.chooser import ChooserViewSet
from wagtail.admin.widgets import BaseChooser
class BaseUserChooseView(BaseChooseView):
@property
def columns(self):
return [
TitleColumn(
"title",
label="Title",
accessor='username',
id_accessor='id',
url_name=self.chosen_url_name,
link_attrs={"data-chooser-modal-choice": True},
),
Column(
"email", label="Email", accessor="email"
)
]
def get_object_list(self):
r = requests.get("http://localhost:8000/api/users/")
r.raise_for_status()
results = r.json()
return results
def apply_object_list_ordering(self, objects):
return objects
class UserChooseView(ChooseViewMixin, CreationFormMixin, BaseUserChooseView):
pass
class UserChooseResultsView(ChooseResultsViewMixin, CreationFormMixin, BaseUserChooseView):
pass
class UserChosenViewMixin(ChosenViewMixin):
def get_object(self, pk):
r = requests.get("http://localhost:8000/api/users/%d/" % int(pk))
r.raise_for_status()
return r.json()
class UserChosenResponseMixin(ChosenResponseMixin):
def get_chosen_response_data(self, item):
return {
"id": item["id"],
"title": item["username"],
}
class UserChosenView(UserChosenViewMixin, UserChosenResponseMixin, View):
pass
class BaseUserChooserWidget(BaseChooser):
def get_instance(self, value):
if value is None:
return None
elif isinstance(value, dict):
return value
else:
r = requests.get("http://localhost:8000/api/users/%d/" % int(value))
r.raise_for_status()
return r.json()
def get_value_data_from_instance(self, instance):
return {
"id": instance["id"],
"title": instance["username"],
}
class UserChooserViewSet(ChooserViewSet):
icon = "user"
choose_one_text = "Choose a user"
choose_another_text = "Choose another user"
edit_item_text = "Edit this user"
choose_view_class = UserChooseView
choose_results_view_class = UserChooseResultsView
chosen_view_class = UserChosenView
base_widget_class = BaseUserChooserWidget
user_chooser_viewset = UserChooserViewSet("user_chooser", url_prefix="user-chooser")
If the data source implements its own pagination - meaning that the pagination mechanism built into the chooser should be bypassed - the BaseChooseView.get_results_page(request) method can be overridden instead of get_object_list. This should return an instance of django.core.paginator.Page. For example, if the API in the above example followed the conventions of the Wagtail API, implementing pagination with offset and limit URL parameters and returning a dict consisting of meta and results, the BaseUserChooseView implementation could be modified as follows:
from django.core.paginator import Page, Paginator
class APIPaginator(Paginator):
"""
Customisation of Django's Paginator class for use when we don't want it to handle
slicing on the result set, but still want it to generate the page numbering based
on a known result count.
"""
def __init__(self, count, per_page, **kwargs):
self._count = int(count)
super().__init__([], per_page, **kwargs)
@property
def count(self):
return self._count
class BaseUserChooseView(BaseChooseView):
@property
def columns(self):
return [
TitleColumn(
"title",
label="Title",
accessor='username',
id_accessor='id',
url_name=self.chosen_url_name,
link_attrs={"data-chooser-modal-choice": True},
),
Column(
"email", label="Email", accessor="email"
)
]
def get_results_page(self, request):
try:
page_number = int(request.GET.get('p', 1))
except ValueError:
page_number = 1
r = requests.get("http://localhost:8000/api/users/", params={
'offset': (page_number - 1) * self.per_page,
'limit': self.per_page,
})
r.raise_for_status()
result = r.json()
paginator = APIPaginator(result['meta']['total_count'], self.per_page)
page = Page(result['items'], page_number, paginator)
return page