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wagtail/docs/topics/pages.md
Andy Chosak e9e1a48b68 Fix broken references in Pages topic documentation
The "Page models" documentation page in the Wagtail usage guide has
several broken links (see current page at
https://docs.wagtail.io/en/stable/topics/pages.html).

These links work when developing the documentation locally, but not when
served on ReadTheDocs (docs.wagtail.io)

The broken links are all of the form /some/page.html#anchor - somehow
this format doesn't translate properly to get the necessary RTD prefix
(for example /en/stable/).

I've modified these links to use RST references, which will also make
them more robust to future changes.
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Page models

Each page type (a.k.a. content type) in Wagtail is represented by a Django model. All page models must inherit from the :class:`wagtail.core.models.Page` class.

As all page types are Django models, you can use any field type that Django provides. See Model field reference for a complete list of field types you can use. Wagtail also provides wagtail.core.fields.RichTextField which provides a WYSIWYG editor for editing rich-text content.

.. note::

    If you're not yet familiar with Django models, have a quick look at the following links to get you started:

    * :ref:`Creating models <django:creating-models>`
    * :doc:`Model syntax <django:topics/db/models>`

An example Wagtail page model

This example represents a typical blog post:

from django.db import models

from modelcluster.fields import ParentalKey

from wagtail.core.models import Page, Orderable
from wagtail.core.fields import RichTextField
from wagtail.admin.edit_handlers import FieldPanel, MultiFieldPanel, InlinePanel
from wagtail.images.edit_handlers import ImageChooserPanel
from wagtail.search import index


class BlogPage(Page):

    # Database fields

    body = RichTextField()
    date = models.DateField("Post date")
    feed_image = models.ForeignKey(
        'wagtailimages.Image',
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name='+'
    )


    # Search index configuration

    search_fields = Page.search_fields + [
        index.SearchField('body'),
        index.FilterField('date'),
    ]


    # Editor panels configuration

    content_panels = Page.content_panels + [
        FieldPanel('date'),
        FieldPanel('body', classname="full"),
        InlinePanel('related_links', label="Related links"),
    ]

    promote_panels = [
        MultiFieldPanel(Page.promote_panels, "Common page configuration"),
        ImageChooserPanel('feed_image'),
    ]


    # Parent page / subpage type rules

    parent_page_types = ['blog.BlogIndex']
    subpage_types = []


class BlogPageRelatedLink(Orderable):
    page = ParentalKey(BlogPage, on_delete=models.CASCADE, related_name='related_links')
    name = models.CharField(max_length=255)
    url = models.URLField()

    panels = [
        FieldPanel('name'),
        FieldPanel('url'),
    ]
.. note::

    Ensure that none of your field names are the same as your class names. This will cause errors due to the way Django handles relations (`read more <https://github.com/wagtail/wagtail/issues/503>`_). In our examples we have avoided this by appending "Page" to each model name.

Writing page models

Here we'll describe each section of the above example to help you create your own page models.

Database fields

Each Wagtail page type is a Django model, represented in the database as a separate table.

Each page type can have its own set of fields. For example, a news article may have body text and a published date, whereas an event page may need separate fields for venue and start/finish times.

In Wagtail, you can use any Django field class. Most field classes provided by third party apps should work as well.

Wagtail also provides a couple of field classes of its own:

For tagging, Wagtail fully supports django-taggit so we recommend using that.

The search_fields attribute defines which fields are added to the search index and how they are indexed.

This should be a list of SearchField and FilterField objects. SearchField adds a field for full-text search. FilterField adds a field for filtering the results. A field can be indexed with both SearchField and FilterField at the same time (but only one instance of each).

In the above example, we've indexed body for full-text search and date for filtering.

The arguments that these field types accept are documented in indexing extra fields.

Editor panels

There are a few attributes for defining how the page's fields will be arranged in the page editor interface:

  • content_panels - For content, such as main body text
  • promote_panels - For metadata, such as tags, thumbnail image and SEO title
  • settings_panels - For settings, such as publish date

Each of these attributes is set to a list of EditHandler objects, which defines which fields appear on which tabs and how they are structured on each tab.

Here's a summary of the EditHandler classes that Wagtail provides out of the box. See Panel types for full descriptions.

Basic

These allow editing of model fields. The FieldPanel class will choose the correct widget based on the type of the field, though StreamField fields need to use a specialised panel class.

-   :class:`~wagtail.admin.edit_handlers.FieldPanel`
-   :class:`~wagtail.admin.edit_handlers.StreamFieldPanel`

Structural

These are used for structuring fields in the interface.

-   :class:`~wagtail.admin.edit_handlers.MultiFieldPanel`
-   :class:`~wagtail.admin.edit_handlers.InlinePanel`
-   :class:`~wagtail.admin.edit_handlers.FieldRowPanel`

Chooser

ForeignKey fields to certain models can use one of the below ChooserPanel classes. These add a nice modal chooser interface, and the image/document choosers also allow uploading new files without leaving the page editor.

-   :class:`~wagtail.admin.edit_handlers.PageChooserPanel`
-   :class:`~wagtail.images.edit_handlers.ImageChooserPanel`
-   :class:`~wagtail.documents.edit_handlers.DocumentChooserPanel`
-   :class:`~wagtail.snippets.edit_handlers.SnippetChooserPanel`

.. note::

    In order to use one of these choosers, the model being linked to must either be a page, image, document or snippet.

    Linking to any other model type is currently unsupported, you will need to use ``FieldPanel`` which will create a dropdown box.

Customising the page editor interface

The page editor can be customised further. See Customising the editing interface.

.. _page_type_business_rules:

Parent page / subpage type rules

These two attributes allow you to control where page types may be used in your site. It allows you to define rules like "blog entries may only be created under a blog index".

Both take a list of model classes or model names. Model names are of the format app_label.ModelName. If the app_label is omitted, the same app is assumed.

  • parent_page_types limits which page types this type can be created under
  • subpage_types limits which page types can be created under this type

By default, any page type can be created under any page type and it is not necessary to set these attributes if that's the desired behaviour.

Setting parent_page_types to an empty list is a good way of preventing a particular page type from being created in the editor interface.

.. _page_urls:

Page URLs

The most common method of retrieving page URLs is by using the {% pageurl %} template tag. Since it's called from a template, pageurl automatically includes the optimizations mentioned below. For more information, see pageurl.

Page models also include several low-level methods for overriding or accessing page URLs.

Customising URL patterns for a page model

The Page.get_url_parts(request) method will not typically be called directly, but may be overridden to define custom URL routing for a given page model. It should return a tuple of (site_id, root_url, page_path), which are used by get_url and get_full_url (see below) to construct the given type of page URL.

When overriding get_url_parts(), you should accept *args, **kwargs:

def get_url_parts(self, *args, **kwargs):

and pass those through at the point where you are calling get_url_parts on super (if applicable), e.g.:

super().get_url_parts(*args, **kwargs)

While you could pass only the request keyword argument, passing all arguments as-is ensures compatibility with any future changes to these method signatures.

For more information, please see :meth:`wagtail.core.models.Page.get_url_parts`.

Obtaining URLs for page instances

The Page.get_url(request) method can be called whenever a page URL is needed. It defaults to returning local URLs (not including the protocol or domain) if it determines that the page is on the current site (via the hostname in request); otherwise, a full URL including the protocol and domain is returned. Whenever possible, the optional request argument should be included to enable per-request caching of site-level URL information and facilitate the generation of local URLs.

A common use case for get_url(request) is in any custom template tag your project may include for generating navigation menus. When writing such a custom template tag, ensure that it includes takes_context=True and use context.get('request') to safely pass the request or None if no request exists in the context.

For more information, please see :meth:`wagtail.core.models.Page.get_url`.

In the event a full URL (including the protocol and domain) is needed, Page.get_full_url(request) can be used instead. Whenever possible, the optional request argument should be included to enable per-request caching of site-level URL information.

For more information, please see :meth:`wagtail.core.models.Page.get_full_url`.

Template rendering

Each page model can be given an HTML template which is rendered when a user browses to a page on the site frontend. This is the simplest and most common way to get Wagtail content to end users (but not the only way).

Adding a template for a page model

Wagtail automatically chooses a name for the template based on the app label and model class name.

Format: <app_label>/<model_name (snake cased)>.html

For example, the template for the above blog page will be: blog/blog_page.html

You just need to create a template in a location where it can be accessed with this name.

Template context

Wagtail renders templates with the page variable bound to the page instance being rendered. Use this to access the content of the page. For example, to get the title of the current page, use {{ page.title }}. All variables provided by context processors are also available.

Customising template context

All pages have a get_context method that is called whenever the template is rendered and returns a dictionary of variables to bind into the template.

To add more variables to the template context, you can override this method:

class BlogIndexPage(Page):
    ...

    def get_context(self, request, *args, **kwargs):
        context = super().get_context(request, *args, **kwargs)

        # Add extra variables and return the updated context
        context['blog_entries'] = BlogPage.objects.child_of(self).live()
        return context

The variables can then be used in the template:

{{ page.title }}

{% for entry in blog_entries %}
    {{ entry.title }}
{% endfor %}

Changing the template

Set the template attribute on the class to use a different template file:

class BlogPage(Page):
    ...

    template = 'other_template.html'

Dynamically choosing the template

The template can be changed on a per-instance basis by defining a get_template method on the page class. This method is called every time the page is rendered:

class BlogPage(Page):
    ...

    use_other_template = models.BooleanField()

    def get_template(self, request, *args, **kwargs):
        if self.use_other_template:
            return 'blog/other_blog_page.html'

        return 'blog/blog_page.html'

In this example, pages that have the use_other_template boolean field set will use the blog/other_blog_page.html template. All other pages will use the default blog/blog_page.html.

Ajax Templates

If you want to add AJAX functionality to a page, such as a paginated listing that updates in-place on the page rather than triggering a full page reload, you can set the ajax_template attribute to specify an alternative template to be used when the page is requested via an AJAX call (as indicated by the X-Requested-With: XMLHttpRequest HTTP header):

class BlogPage(Page):
    ...

    ajax_template = 'other_template_fragment.html'
    template = 'other_template.html'

More control over page rendering

All page classes have a serve() method that internally calls the get_context and get_template methods and renders the template. This method is similar to a Django view function, taking a Django Request object and returning a Django Response object.

This method can also be overridden for complete control over page rendering.

For example, here's a way to make a page respond with a JSON representation of itself:

from django.http import JsonResponse


class BlogPage(Page):
    ...

    def serve(self, request):
        return JsonResponse({
            'title': self.title,
            'body': self.body,
            'date': self.date,

            # Resizes the image to 300px width and gets a URL to it
            'feed_image': self.feed_image.get_rendition('width-300').url,
        })

Inline models

Wagtail can nest the content of other models within the page. This is useful for creating repeated fields, such as related links or items to display in a carousel. Inline model content is also versioned with the rest of the page content.

Each inline model requires the following:

-   It must inherit from :class:`wagtail.core.models.Orderable`
-   It must have a `ParentalKey` to the parent model

.. note:: django-modelcluster and ParentalKey

    The model inlining feature is provided by `django-modelcluster <https://github.com/torchbox/django-modelcluster>`_ and the ``ParentalKey`` field type must be imported from there:

    .. code-block:: python

        from modelcluster.fields import ParentalKey

    ``ParentalKey`` is a subclass of Django's ``ForeignKey``, and takes the same arguments.

For example, the following inline model can be used to add related links (a list of name, url pairs) to the BlogPage model:

from django.db import models
from modelcluster.fields import ParentalKey
from wagtail.core.models import Orderable


class BlogPageRelatedLink(Orderable):
    page = ParentalKey(BlogPage, on_delete=models.CASCADE, related_name='related_links')
    name = models.CharField(max_length=255)
    url = models.URLField()

    panels = [
        FieldPanel('name'),
        FieldPanel('url'),
    ]
To add this to the admin interface, use the :class:`~wagtail.admin.edit_handlers.InlinePanel` edit panel class:
content_panels = [
    ...

    InlinePanel('related_links', label="Related links"),
]

The first argument must match the value of the related_name attribute of the ParentalKey.

Working with pages

Wagtail uses Django's multi-table inheritance feature to allow multiple page models to be used in the same tree.

Each page is added to both Wagtail's builtin :class:`~wagtail.core.models.Page` model as well as its user-defined model (such as the `BlogPage` model created earlier).

Pages can exist in Python code in two forms, an instance of Page or an instance of the page model.

When working with multiple page types together, you will typically use instances of Wagtail's Page model, which don't give you access to any fields specific to their type.

# Get all pages in the database
>>> from wagtail.core.models import Page
>>> Page.objects.all()
[<Page: Homepage>, <Page: About us>, <Page: Blog>, <Page: A Blog post>, <Page: Another Blog post>]

When working with a single page type, you can work with instances of the user-defined model. These give access to all the fields available in Page, along with any user-defined fields for that type.

# Get all blog entries in the database
>>> BlogPage.objects.all()
[<BlogPage: A Blog post>, <BlogPage: Another Blog post>]

You can convert a Page object to its more specific user-defined equivalent using the .specific property. This may cause an additional database lookup.

>>> page = Page.objects.get(title="A Blog post")
>>> page
<Page: A Blog post>

# Note: the blog post is an instance of Page so we cannot access body, date or feed_image

>>> page.specific
<BlogPage: A Blog post>

Tips

Friendly model names

You can make your model names more friendly to users of Wagtail by using Django's internal Meta class with a verbose_name, e.g.:

class HomePage(Page):
    ...

    class Meta:
        verbose_name = "homepage"

When users are given a choice of pages to create, the list of page types is generated by splitting your model names on each of their capital letters. Thus a HomePage model would be named "Home Page" which is a little clumsy. Defining verbose_name as in the example above would change this to read "Homepage", which is slightly more conventional.

Page QuerySet ordering

Page-derived models cannot be given a default ordering by using the standard Django approach of adding an ordering attribute to the internal Meta class.

class NewsItemPage(Page):
    publication_date = models.DateField()
    ...

    class Meta:
        ordering = ('-publication_date', )  # will not work

This is because Page enforces ordering QuerySets by path. Instead, you must apply the ordering explicitly when constructing a QuerySet:

news_items = NewsItemPage.objects.live().order_by('-publication_date')
.. _custom_page_managers:

Custom Page managers

You can add a custom Manager to your Page class. Any custom Managers should inherit from wagtail.core.models.PageManager:

from django.db import models
from wagtail.core.models import Page, PageManager

class EventPageManager(PageManager):
    """ Custom manager for Event pages """

class EventPage(Page):
    start_date = models.DateField()

    objects = EventPageManager()

Alternately, if you only need to add extra QuerySet methods, you can inherit from wagtail.core.models.PageQuerySet to build a custom Manager:

from django.db import models
from django.utils import timezone
from wagtail.core.models import Page, PageManager, PageQuerySet

class EventPageQuerySet(PageQuerySet):
    def future(self):
        today = timezone.localtime(timezone.now()).date()
        return self.filter(start_date__gte=today)

EventPageManager = PageManager.from_queryset(EventPageQuerySet)

class EventPage(Page):
    start_date = models.DateField()

    objects = EventPageManager()