18 KiB
(wagtailsnippets_features)=
Optional features
By default, snippets lack many of the features of pages, such as previews, revisions, and workflows. These features can individually be added to each snippet model by inheriting from the appropriate mixin classes.
(wagtailsnippets_making_snippets_previewable)=
Making snippets previewable
If a snippet model inherits from {class}~wagtail.models.PreviewableMixin, Wagtail will automatically add a live preview panel in the editor. In addition to inheriting the mixin, the model must also override {meth}~wagtail.models.PreviewableMixin.get_preview_template or {meth}~wagtail.models.PreviewableMixin.serve_preview. For example, the Advert snippet could be made previewable as follows:
# ...
from wagtail.models import PreviewableMixin
# ...
class Advert(PreviewableMixin, models.Model):
url = models.URLField(null=True, blank=True)
text = models.CharField(max_length=255)
panels = [
FieldPanel('url'),
FieldPanel('text'),
]
def get_preview_template(self, request, mode_name):
return "demo/previews/advert.html"
With the following demo/previews/advert.html template:
<!DOCTYPE html>
<html>
<head>
<title>{{ object.text }}</title>
</head>
<body>
<a href="{{ object.url }}">{{ object.text }}</a>
</body>
</html>
The variables available in the default context are request (a fake {class}~django.http.HttpRequest object) and object (the snippet instance). To customise the context, you can override the {meth}~wagtail.models.PreviewableMixin.get_preview_context method.
By default, the serve_preview method returns a {class}~django.template.response.TemplateResponse that is rendered using the request object, the template returned by get_preview_template, and the context object returned by get_preview_context. You can override the serve_preview method to customise the rendering and/or routing logic.
Similar to pages, you can define multiple preview modes by overriding the {attr}~wagtail.models.PreviewableMixin.preview_modes property. For example, the following Advert snippet has two preview modes:
# ...
from wagtail.models import PreviewableMixin
# ...
class Advert(PreviewableMixin, models.Model):
url = models.URLField(null=True, blank=True)
text = models.CharField(max_length=255)
panels = [
FieldPanel('url'),
FieldPanel('text'),
]
@property
def preview_modes(self):
return PreviewableMixin.DEFAULT_PREVIEW_MODES + [("alt", "Alternate")]
def get_preview_template(self, request, mode_name):
templates = {
"": "demo/previews/advert.html", # Default preview mode
"alt": "demo/previews/advert_alt.html", # Alternate preview mode
}
return templates.get(mode_name, templates[""])
def get_preview_context(self, request, mode_name):
context = super().get_preview_context(request, mode_name)
if mode_name == "alt":
context["extra_context"] = "Alternate preview mode"
return context
(wagtailsnippets_making_snippets_searchable)=
Making snippets searchable
If a snippet model inherits from {class}wagtail.search.index.Indexed, as described in , Wagtail will automatically add a search box to the chooser interface for that snippet type. For example, the Advert snippet could be made searchable as follows:
# ...
from wagtail.search import index
# ...
class Advert(index.Indexed, models.Model):
url = models.URLField(null=True, blank=True)
text = models.CharField(max_length=255)
panels = [
FieldPanel('url'),
FieldPanel('text'),
]
search_fields = [
index.SearchField('text'),
index.AutocompleteField('text'),
]
(wagtailsnippets_saving_revisions_of_snippets)=
Saving revisions of snippets
If a snippet model inherits from {class}~wagtail.models.RevisionMixin, Wagtail will automatically save revisions when you save any changes in the snippets admin.
In addition to inheriting the mixin, it is highly recommended to define a {class}~django.contrib.contenttypes.fields.GenericRelation to the {class}~wagtail.models.Revision model as the {attr}~wagtail.models.RevisionMixin.revisions attribute so that you can do related queries. Defining the GenericRelation is also necessary to ensure that Revision instances are automatically deleted when the snippet instance is deleted. If you need to customise how the revisions are fetched (for example, to handle the content type to use for models with multi-table inheritance), you can define the revisions as a property.
For example, the Advert snippet could be made revisable as follows:
# ...
from django.contrib.contenttypes.fields import GenericRelation
from wagtail.models import RevisionMixin
# ...
class Advert(RevisionMixin, models.Model):
url = models.URLField(null=True, blank=True)
text = models.CharField(max_length=255)
# If no custom logic is required, this can be defined as `revisions` directly
_revisions = GenericRelation("wagtailcore.Revision", related_query_name="advert")
panels = [
FieldPanel('url'),
FieldPanel('text'),
]
@property
def revisions(self):
# Some custom logic here if necessary
return self._revisions
If your snippet model defines relations using Django's {class}~django.db.models.ManyToManyField, you need to change the model class to inherit from modelcluster.models.ClusterableModel instead of django.models.Model and replace the ManyToManyField with ParentalManyToManyField. Inline models should continue to use ParentalKey instead of ForeignKey. This is necessary in order to allow the relations to be stored in the revisions. See the section of the tutorial for more details. For example:
# ...
from django.db import models
from modelcluster.fields import ParentalKey, ParentalManyToManyField
from modelcluster.models import ClusterableModel
from wagtail.models import RevisionMixin
# ...
class ShirtColour(models.Model):
name = models.CharField(max_length=255)
panels = [FieldPanel("name")]
class ShirtCategory(models.Model):
name = models.CharField(max_length=255)
panels = [FieldPanel("name")]
class Shirt(RevisionMixin, ClusterableModel):
name = models.CharField(max_length=255)
colour = models.ForeignKey("shirts.ShirtColour", on_delete=models.SET_NULL, blank=True, null=True)
categories = ParentalManyToManyField("shirts.ShirtCategory", blank=True)
revisions = GenericRelation("wagtailcore.Revision", related_query_name="shirt")
panels = [
FieldPanel("name"),
FieldPanel("colour"),
FieldPanel("categories", widget=forms.CheckboxSelectMultiple),
InlinePanel("images", label="Images"),
]
class ShirtImage(models.Model):
shirt = ParentalKey("shirts.Shirt", related_name="images")
image = models.ForeignKey("wagtailimages.Image", on_delete=models.CASCADE, related_name="+")
caption = models.CharField(max_length=255, blank=True)
panels = [
FieldPanel("image"),
FieldPanel("caption"),
]
The RevisionMixin includes a latest_revision field that needs to be added to your database table. Make sure to run the makemigrations and migrate management commands after making the above changes to apply the changes to your database.
With the RevisionMixin applied, any changes made from the snippets admin will create an instance of the Revision model that contains the state of the snippet instance. The revision instance is attached to the audit log entry of the edit action, allowing you to revert to a previous revision or compare the changes between revisions from the snippet history page.
You can also save revisions programmatically by calling the {meth}~wagtail.models.RevisionMixin.save_revision method. After applying the mixin, it is recommended to call this method (or save the snippet in the admin) at least once for each instance of the snippet that already exists (if any), so that the latest_revision field is populated in the database table.
(wagtailsnippets_saving_draft_changes_of_snippets)=
Saving draft changes of snippets
If a snippet model inherits from {class}~wagtail.models.DraftStateMixin, Wagtail will automatically add a live/draft status column to the listing view, change the "Save" action menu to "Save draft", and add a new "Publish" action menu in the editor. Any changes you save in the snippets admin will be saved as revisions and will not be reflected in the "live" snippet instance until you publish the changes.
As the DraftStateMixin works by saving draft changes as revisions, inheriting from this mixin also requires inheriting from RevisionMixin. See above for more details.
Wagtail will also allow you to set publishing schedules for instances of the model if there is a PublishingPanel in the model's panels definition.
For example, the Advert snippet could save draft changes and publishing schedules by defining it as follows:
# ...
from django.contrib.contenttypes.fields import GenericRelation
from wagtail.admin.panels import PublishingPanel
from wagtail.models import DraftStateMixin, RevisionMixin
# ...
class Advert(DraftStateMixin, RevisionMixin, models.Model):
url = models.URLField(null=True, blank=True)
text = models.CharField(max_length=255)
_revisions = GenericRelation("wagtailcore.Revision", related_query_name="advert")
panels = [
FieldPanel('url'),
FieldPanel('text'),
PublishingPanel(),
]
@property
def revisions(self):
return self._revisions
The DraftStateMixin includes additional fields that need to be added to your database table. Make sure to run the makemigrations and migrate management commands after making the above changes to apply the changes to your database.
You can publish revisions programmatically by calling {meth}instance.publish(revision) <wagtail.models.DraftStateMixin.publish> or by calling {meth}revision.publish() <wagtail.models.Revision.publish>. After applying the mixin, it is recommended to publish at least one revision for each instance of the snippet that already exists (if any), so that the latest_revision and live_revision fields are populated in the database table.
If you use the scheduled publishing feature, make sure that you run the publish_scheduled management command periodically. For more details, see .
Publishing a snippet instance requires publish permission on the snippet model. For models with DraftStateMixin applied, Wagtail automatically creates the corresponding publish permissions and display them in the 'Groups' area of the Wagtail admin interface. For more details on how to configure the permission, see .
Wagtail does not yet have a mechanism to prevent editors from including unpublished ("draft") snippets in pages. When including a `DraftStateMixin`-enabled snippet in pages, make sure that you add necessary checks to handle how a draft snippet should be rendered (for example, by checking its `live` field). We are planning to improve this in the future.
(wagtailsnippets_locking_snippets)=
Locking snippets
If a snippet model inherits from {class}~wagtail.models.LockableMixin, Wagtail will automatically add the ability to lock instances of the model. When editing, Wagtail will show the locking information in the "Status" side panel, and a button to lock/unlock the instance if the user has the permission to do so.
If the model is also configured to have scheduled publishing (as shown in above), Wagtail will lock any instances that are scheduled for publishing.
Similar to pages, users who locked a snippet can still edit it, unless WAGTAILADMIN_GLOBAL_EDIT_LOCK is set to True.
For example, instances of the Advert snippet could be locked by defining it as follows:
# ...
from wagtail.models import LockableMixin
# ...
class Advert(LockableMixin, models.Model):
url = models.URLField(null=True, blank=True)
text = models.CharField(max_length=255)
panels = [
FieldPanel('url'),
FieldPanel('text'),
]
If you use the other mixins, make sure to apply LockableMixin after the other mixins, but before the RevisionMixin (in left-to-right order). For example, with DraftStateMixin and RevisionMixin, the correct inheritance of the model would be class MyModel(DraftStateMixin, LockableMixin, RevisionMixin). There is a system check to enforce the ordering of the mixins.
The LockableMixin includes additional fields that need to be added to your database table. Make sure to run the makemigrations and migrate management commands after making the above changes to apply the changes to your database.
Locking and unlocking a snippet instance requires lock and unlock permissions on the snippet model, respectively. For models with LockableMixin applied, Wagtail automatically creates the corresponding lock and unlock permissions and display them in the 'Groups' area of the Wagtail admin interface. For more details on how to configure the permission, see .
(wagtailsnippets_enabling_workflows)=
Enabling workflows for snippets
If a snippet model inherits from {class}~wagtail.models.WorkflowMixin, Wagtail will automatically add the ability to assign a workflow to the model. With a workflow assigned to the snippet model, a "Submit for moderation" and other workflow action menu items will be shown in the editor. The status side panel will also show the information of the current workflow.
Since the WorkflowMixin utilises revisions and publishing mechanisms in Wagtail, inheriting from this mixin also requires inheriting from RevisionMixin and DraftStateMixin. It is also recommended to enable locking by inheriting from LockableMixin, so that the snippet instance can be locked and only editable by reviewers when it is in a workflow. See the above sections for more details.
In addition to inheriting the mixins, it is highly recommended to define a {class}~django.contrib.contenttypes.fields.GenericRelation to the {class}~wagtail.models.WorkflowState model so that you can do related queries and that the workflow-related data is properly cleaned up when the snippet instance is deleted.
For example, workflows (with locking) can be enabled for the Advert snippet by defining it as follows:
# ...
from wagtail.models import DraftStateMixin, LockableMixin, RevisionMixin, WorkflowMixin
# ...
class Advert(WorkflowMixin, DraftStateMixin, LockableMixin, RevisionMixin, models.Model):
url = models.URLField(null=True, blank=True)
text = models.CharField(max_length=255)
_revisions = GenericRelation("wagtailcore.Revision", related_query_name="advert")
workflow_states = GenericRelation(
"wagtailcore.WorkflowState",
content_type_field="base_content_type",
object_id_field="object_id",
related_query_name="advert",
for_concrete_model=False,
)
panels = [
FieldPanel('url'),
FieldPanel('text'),
]
@property
def revisions(self):
return self._revisions
The other mixins required by WorkflowMixin includes additional fields that need to be added to your database table. Make sure to run the makemigrations and migrate management commands after making the above changes to apply the changes to your database.
After enabling the mixin, you can assign a workflow to the snippet models through the workflow settings. For more information, see how to configure workflows for moderation.
The admin dashboard and workflow reports will also show you snippets (alongside pages) that have been submitted to workflows.
Tagging snippets
Adding tags to snippets is very similar to adding tags to pages. The only difference is that if RevisionMixin is not applied, then {class}taggit.manager.TaggableManager should be used in the place of {class}~modelcluster.contrib.taggit.ClusterTaggableManager.
# ...
from modelcluster.fields import ParentalKey
from modelcluster.models import ClusterableModel
from taggit.models import TaggedItemBase
from taggit.managers import TaggableManager
# ...
class AdvertTag(TaggedItemBase):
content_object = ParentalKey('demo.Advert', on_delete=models.CASCADE, related_name='tagged_items')
class Advert(ClusterableModel):
# ...
tags = TaggableManager(through=AdvertTag, blank=True)
panels = [
# ...
FieldPanel('tags'),
]
The documentation on tagging pages has more information on how to use tags in views.
(wagtailsnippets_inline_models)=
Inline models within snippets
Similar to pages, you can nest other models within a snippet.
from django.db import models
from modelcluster.fields import ParentalKey
from wagtail.models import Orderable
class BandMember(Orderable):
band = ParentalKey("music.Band", related_name="members", on_delete=models.CASCADE)
name = models.CharField(max_length=255)
@register_snippet
class Band(ClusterableModel):
name = models.CharField(max_length=255)
panels = [
FieldPanel("name"),
InlinePanel("members")
]
The documentation on how to use inline models with pages provides more information that is also applicable to snippets.