Split out common logic from get_value_data

wagtail/admin/widgets/chooser.py

@@ -157,13 +157,39 @@ class BaseChooser(widgets.Input):
             self.get_context(name, value_data or {}, attrs),
         )
 
+    def get_instance(self, value):
+        """
+        Given a value passed to this widget for rendering (which may be None, an id, or a model
+        instance), return a model instance or None
+        """
+        if value is None:
+            return None
+        elif isinstance(value, self.model):
+            return value
+        else:  # assume instance ID
+            return self.model.objects.get(pk=value)
+
+    def get_value_data_from_instance(self, instance):
+        """
+        Given a model instance, return a value that we can pass to both the server-side template
+        and the client-side rendering code (via telepath) that contains all the information needed
+        for display. Typically this is a dict of id, title etc; it must be JSON-serialisable.
+        """
+        return {
+            "id": instance.pk,
+            "edit_url": AdminURLFinder().get_edit_url(instance),
+        }
+
     def get_value_data(self, value):
-        # Perform any necessary preprocessing on the value passed to render() before it is passed
-        # on to render_html / render_js_init. This is a good place to perform database lookups
-        # that are needed by both render_html and render_js_init. Return value is arbitrary
-        # (we only care that render_html / render_js_init can accept it), but will typically be
-        # a dict of data needed for rendering: id, title etc.
-        return value
+        """
+        Given a value passed to this widget for rendering (which may be None, an id, or a model
+        instance), return a value that we can pass to both the server-side template and the
+        client-side rendering code (via telepath) that contains all the information needed
+        for display. Typically this is a dict of id, title etc; it must be JSON-serialisable.
+        """
+        instance = self.get_instance(value)
+        if instance:
+            return self.get_value_data_from_instance(instance)
 
     def render(self, name, value, attrs=None, renderer=None):
         # no point trying to come up with sensible semantics for when 'id' is missing from attrs,
@@ -244,27 +270,21 @@ class AdminPageChooser(BaseChooser):
             "user_perms": self.user_perms,
         }
 
-    def get_value_data(self, value):
-        if value is None:
-            return None
-        elif isinstance(value, Page):
-            page = value.specific
-        else:  # assume page ID
-            try:
-                page = self.model.objects.get(pk=value)
-            except self.model.DoesNotExist:
-                return None
+    def get_instance(self, value):
+        instance = super().get_instance(value)
+        if instance:
+            return instance.specific
 
-            page = page.specific
-
-        edit_url = AdminURLFinder().get_edit_url(page)
-        parent_page = page.get_parent()
-        return {
-            "id": page.pk,
-            "display_title": page.get_admin_display_title(),
-            "parent_id": parent_page.pk if parent_page else None,
-            "edit_url": edit_url,
-        }
+    def get_value_data_from_instance(self, instance):
+        data = super().get_value_data_from_instance(instance)
+        parent_page = instance.get_parent()
+        data.update(
+            {
+                "display_title": instance.get_admin_display_title(),
+                "parent_id": parent_page.pk if parent_page else None,
+            }
+        )
+        return data
 
     def get_context(self, name, value_data, attrs):
         context = super().get_context(name, value_data, attrs)

wagtail/admin/widgets/workflows.py

@@ -4,7 +4,6 @@ from django import forms
 from django.urls import reverse
 from django.utils.translation import gettext_lazy as _
 
-from wagtail.admin.admin_url_finder import AdminURLFinder
 from wagtail.admin.staticfiles import versioned_static
 from wagtail.admin.widgets import BaseChooser
 from wagtail.models import Task
@@ -17,21 +16,10 @@ class AdminTaskChooser(BaseChooser):
     model = Task
     template_name = "wagtailadmin/workflows/widgets/task_chooser.html"
 
-    def get_value_data(self, value):
-        if value is None:
-            return None
-        elif isinstance(value, self.model):
-            instance = value
-        else:  # assume ID
-            instance = self.model.objects.get(pk=value)
-
-        edit_url = AdminURLFinder().get_edit_url(instance)
-
-        return {
-            "id": instance.pk,
-            "title": instance.name,
-            "edit_url": edit_url,
-        }
+    def get_value_data_from_instance(self, instance):
+        data = super().get_value_data_from_instance(instance)
+        data["title"] = instance.name
+        return data
 
     def get_context(self, name, value_data, attrs):
         context = super().get_context(name, value_data, attrs)

wagtail/documents/widgets.py

@@ -5,7 +5,6 @@ from django.urls import reverse
 from django.utils.functional import cached_property
 from django.utils.translation import gettext_lazy as _
 
-from wagtail.admin.admin_url_finder import AdminURLFinder
 from wagtail.admin.staticfiles import versioned_static
 from wagtail.admin.widgets import BaseChooser
 from wagtail.documents import get_document_model
@@ -22,21 +21,10 @@ class AdminDocumentChooser(BaseChooser):
         super().__init__(**kwargs)
         self.model = get_document_model()
 
-    def get_value_data(self, value):
-        if value is None:
-            return None
-        elif isinstance(value, self.model):
-            doc = value
-        else:  # assume document ID
-            doc = self.model.objects.get(pk=value)
-
-        edit_url = AdminURLFinder().get_edit_url(doc)
-
-        return {
-            "id": doc.pk,
-            "title": doc.title,
-            "edit_url": edit_url,
-        }
+    def get_value_data_from_instance(self, instance):
+        data = super().get_value_data_from_instance(instance)
+        data["title"] = instance.title
+        return data
 
     def get_context(self, name, value_data, attrs):
         context = super().get_context(name, value_data, attrs)

wagtail/images/widgets.py

@@ -5,7 +5,6 @@ from django.urls import reverse
 from django.utils.functional import cached_property
 from django.utils.translation import gettext_lazy as _
 
-from wagtail.admin.admin_url_finder import AdminURLFinder
 from wagtail.admin.staticfiles import versioned_static
 from wagtail.admin.widgets import BaseChooser
 from wagtail.images import get_image_model
@@ -24,27 +23,20 @@ class AdminImageChooser(BaseChooser):
         super().__init__(**kwargs)
         self.model = get_image_model()
 
-    def get_value_data(self, value):
-        if value is None:
-            return None
-        elif isinstance(value, self.model):
-            image = value
-        else:  # assume image ID
-            image = self.model.objects.get(pk=value)
-
-        preview_image = get_rendition_or_not_found(image, "max-165x165")
-        edit_url = AdminURLFinder().get_edit_url(image)
-
-        return {
-            "id": image.pk,
-            "title": image.title,
-            "preview": {
-                "url": preview_image.url,
-                "width": preview_image.width,
-                "height": preview_image.height,
-            },
-            "edit_url": edit_url,
-        }
+    def get_value_data_from_instance(self, instance):
+        data = super().get_value_data_from_instance(instance)
+        preview_image = get_rendition_or_not_found(instance, "max-165x165")
+        data.update(
+            {
+                "title": instance.title,
+                "preview": {
+                    "url": preview_image.url,
+                    "width": preview_image.width,
+                    "height": preview_image.height,
+                },
+            }
+        )
+        return data
 
     def get_context(self, name, value_data, attrs):
         context = super().get_context(name, value_data, attrs)

wagtail/snippets/widgets.py

@@ -5,7 +5,6 @@ from django.urls import reverse
 from django.utils.functional import cached_property
 from django.utils.translation import gettext_lazy as _
 
-from wagtail.admin.admin_url_finder import AdminURLFinder
 from wagtail.admin.staticfiles import versioned_static
 from wagtail.admin.widgets import BaseChooser
 from wagtail.admin.widgets.button import ListingButton
@@ -23,21 +22,10 @@ class AdminSnippetChooser(BaseChooser):
 
         super().__init__(**kwargs)
 
-    def get_value_data(self, value):
-        if value is None:
-            return None
-        elif isinstance(value, self.model):
-            instance = value
-        else:  # assume instance ID
-            instance = self.model.objects.get(pk=value)
-
-        edit_url = AdminURLFinder().get_edit_url(instance)
-
-        return {
-            "id": instance.pk,
-            "string": str(instance),
-            "edit_url": edit_url,
-        }
+    def get_value_data_from_instance(self, instance):
+        data = super().get_value_data_from_instance(instance)
+        data["string"] = str(instance)
+        return data
 
     def get_context(self, name, value_data, attrs):
         context = super().get_context(name, value_data, attrs)