add on_delete argument to ParentalKey & ForeignKey

docs/advanced_topics/api/v2/configuration.rst

@@ -114,7 +114,7 @@ For example:
     from wagtail.api import APIField
 
     class BlogPageAuthor(Orderable):
-        page = models.ForeignKey('blog.BlogPage', related_name='authors')
+        page = models.ForeignKey('blog.BlogPage', on_delete=models.CASCADE, related_name='authors')
         name = models.CharField(max_length=255)
 
         api_fields = [
@@ -125,7 +125,7 @@ For example:
     class BlogPage(Page):
         published_date = models.DateTimeField()
         body = RichTextField()
-        feed_image = models.ForeignKey('wagtailimages.Image', ...)
+        feed_image = models.ForeignKey('wagtailimages.Image', on_delete=models.CASCADE, ...)
         private_field = models.CharField(max_length=255)
 
         # Export fields over the API

docs/advanced_topics/i18n/index.rst

@@ -143,7 +143,7 @@ For each field you would like to be translatable, duplicate it for every languag
         body_fr = StreamField(...)
 
         # Language-independent fields don't need to be duplicated
-        thumbnail_image = models.ForeignKey('wagtailimages.image', ...)
+        thumbnail_image = models.ForeignKey('wagtailimages.image', on_delete=models.CASCADE, ...)
 
 .. note::
 

docs/advanced_topics/images/custom_image_model.rst

@@ -39,7 +39,7 @@ Here's an example:
 
 
     class CustomRendition(AbstractRendition):
-        image = models.ForeignKey(CustomImage, related_name='renditions')
+        image = models.ForeignKey(CustomImage, on_delete=models.CASCADE, related_name='renditions')
 
         class Meta:
             unique_together = (

docs/getting_started/tutorial.rst

@@ -436,7 +436,7 @@ Add a new ``BlogPageGalleryImage`` model to ``models.py``:
 
 
     class BlogPageGalleryImage(Orderable):
-        page = ParentalKey(BlogPage, related_name='gallery_images')
+        page = ParentalKey(BlogPage, on_delete=models.CASCADE, related_name='gallery_images')
         image = models.ForeignKey(
             'wagtailimages.Image', on_delete=models.CASCADE, related_name='+'
         )

docs/reference/contrib/forms/customisation.rst

@@ -23,7 +23,7 @@ You can do this as shown below.
 
 
     class FormField(AbstractFormField):
-        page = ParentalKey('FormPage', related_name='custom_form_fields')
+        page = ParentalKey('FormPage', on_delete=models.CASCADE, related_name='custom_form_fields')
 
 
     class FormPage(AbstractEmailForm):
@@ -74,7 +74,7 @@ Example:
 
 
     class FormField(AbstractFormField):
-        page = ParentalKey('FormPage', related_name='form_fields')
+        page = ParentalKey('FormPage', on_delete=models.CASCADE, related_name='form_fields')
 
 
     class FormPage(AbstractEmailForm):
@@ -135,7 +135,7 @@ The following example shows how to add a username to the CSV export:
 
 
     class FormField(AbstractFormField):
-        page = ParentalKey('FormPage', related_name='form_fields')
+        page = ParentalKey('FormPage', on_delete=models.CASCADE, related_name='form_fields')
 
 
     class FormPage(AbstractEmailForm):
@@ -213,7 +213,7 @@ Example:
 
 
     class FormField(AbstractFormField):
-        page = ParentalKey('FormPage', related_name='form_fields')
+        page = ParentalKey('FormPage', on_delete=models.CASCADE, related_name='form_fields')
 
 
     class FormPage(AbstractEmailForm):
@@ -309,7 +309,7 @@ The following example shows how to create a multi-step form.
 
 
     class FormField(AbstractFormField):
-        page = ParentalKey('FormPage', related_name='form_fields')
+        page = ParentalKey('FormPage', on_delete=models.CASCADE, related_name='form_fields')
 
 
     class FormPage(AbstractEmailForm):
@@ -455,7 +455,7 @@ First, you need to collect results as shown below:
 
 
     class FormField(AbstractFormField):
-        page = ParentalKey('FormPage', related_name='form_fields')
+        page = ParentalKey('FormPage', on_delete=models.CASCADE, related_name='form_fields')
 
 
     class FormPage(AbstractEmailForm):

docs/reference/contrib/forms/index.rst

@@ -38,7 +38,7 @@ Within the ``models.py`` of one of your apps, create a model that extends ``wagt
 
 
     class FormField(AbstractFormField):
-        page = ParentalKey('FormPage', related_name='form_fields')
+        page = ParentalKey('FormPage', on_delete=models.CASCADE, related_name='form_fields')
 
 
     class FormPage(AbstractEmailForm):

docs/reference/pages/model_recipes.rst

@@ -150,7 +150,7 @@ Using an example from the Wagtail demo site, here's what the tag model and the r
     from taggit.models import TaggedItemBase
 
     class BlogPageTag(TaggedItemBase):
-        content_object = ParentalKey('demo.BlogPage', related_name='tagged_items')
+        content_object = ParentalKey('demo.BlogPage', on_delete=models.CASCADE, related_name='tagged_items')
 
     class BlogPage(Page):
         ...

docs/reference/pages/panels.rst

@@ -318,7 +318,7 @@ Let's look at the example of adding related links to a :class:`~wagtail.core.mod
   # Orderable helper class, and what amounts to a ForeignKey link
   # to the model we want to add related links to (BookPage)
   class BookPageRelatedLinks(Orderable, RelatedLink):
-      page = ParentalKey('demo.BookPage', related_name='related_links')
+      page = ParentalKey('demo.BookPage', on_delete=models.CASCADE, related_name='related_links')
 
   class BookPage(Page):
     # ...

docs/topics/pages.rst

@@ -77,7 +77,7 @@ This example represents a typical blog post:
 
 
     class BlogPageRelatedLink(Orderable):
-        page = ParentalKey(BlogPage, related_name='related_links')
+        page = ParentalKey(BlogPage, on_delete=models.CASCADE, related_name='related_links')
         name = models.CharField(max_length=255)
         url = models.URLField()
 
@@ -384,7 +384,7 @@ For example, the following inline model can be used to add related links (a list
 
 
     class BlogPageRelatedLink(Orderable):
-        page = ParentalKey(BlogPage, related_name='related_links')
+        page = ParentalKey(BlogPage, on_delete=models.CASCADE, related_name='related_links')
         name = models.CharField(max_length=255)
         url = models.URLField()
 

docs/topics/search/indexing.rst

@@ -219,7 +219,7 @@ To do this, inherit from ``index.Indexed`` and add some ``search_fields`` to the
     class Book(index.Indexed, models.Model):
         title = models.CharField(max_length=255)
         genre = models.CharField(max_length=255, choices=GENRE_CHOICES)
-        author = models.ForeignKey(Author)
+        author = models.ForeignKey(Author, on_delete=models.CASCADE)
         published_date = models.DateTimeField()
 
         search_fields = [

docs/topics/snippets.rst

@@ -137,8 +137,8 @@ To attach multiple adverts to a page, the ``SnippetChooserPanel`` can be placed
   ...
 
   class BookPageAdvertPlacement(Orderable, models.Model):
-      page = ParentalKey('demo.BookPage', related_name='advert_placements')
-      advert = models.ForeignKey('demo.Advert', related_name='+')
+      page = ParentalKey('demo.BookPage', on_delete=models.CASCADE, related_name='advert_placements')
+      advert = models.ForeignKey('demo.Advert', on_delete=models.CASCADE, related_name='+')
 
       class Meta:
           verbose_name = "advert placement"
@@ -218,7 +218,7 @@ Adding tags to snippets is very similar to adding tags to pages. The only differ
     from taggit.managers import TaggableManager
 
     class AdvertTag(TaggedItemBase):
-        content_object = ParentalKey('demo.Advert', related_name='tagged_items')
+        content_object = ParentalKey('demo.Advert', on_delete=models.CASCADE, related_name='tagged_items')
 
     @register_snippet
     class Advert(ClusterableModel):