Fixed the breadcrumb of the object_history template.

NOTE: this could conflict with projects that use django-reversion,
if the `VersionAdmin` is the last in the inheritance chain.

docs/changelog.rst

@@ -8,6 +8,10 @@ Changes in git
 * Fixed Django 1.7 ``changeform_view()`` redirection to the child admin site.
   This fixes custom admin code that uses these views, such as django-reversion_'s ``revision_view()`` / ``recover_view()``.
 * Fixed ``.only('pk')`` field support.
+* Fixed ``object_history_template`` breadcrumb.
+  **NOTE:** when using django-reversion_ / django-reversion-compare_, make sure to implement
+  a ``admin/polymorphic/object_history.html`` template in your project that extends
+  from ``reversion/object_history.html`` or ``reversion-compare/object_history.html`` respectively.
 
 
 Version 0.9 (2016-02-17)

docs/third-party.rst

@@ -12,6 +12,7 @@ However, they require more setup than standard models. That's become:
 * Polymorphic models use `multi-table inheritance <https://docs.djangoproject.com/en/dev/topics/db/models/#multi-table-inheritance>`_.
   See the `reversion documentation <http://django-reversion.readthedocs.org/en/latest/api.html#multi-table-inheritance>`_
   how to deal with this by adding a ``follow`` field for the primary key.
+* Both admin classes redefine ``object_history_template``.
 
 
 Example
@@ -28,14 +29,14 @@ The admin :ref:`admin-example` becomes:
     from .models import ModelA, ModelB, ModelC
 
 
-    class ModelAChildAdmin(PolymorphicChildModelAdmin):
+    class ModelAChildAdmin(PolymorphicChildModelAdmin, VersionAdmin):
         base_model = ModelA
         base_form = ...
         base_fieldsets = (
             ...
         )
 
-    class ModelBAdmin(VersionAdmin, ModelAChildAdmin):
+    class ModelBAdmin(ModelAChildAdmin, VersionAdmin):
         # define custom features here
 
     class ModelCAdmin(ModelBAdmin):
@@ -53,6 +54,19 @@ The admin :ref:`admin-example` becomes:
     revisions.register(ModelC, follow=['modelb_ptr'])
     admin.site.register(ModelA, ModelAParentAdmin)
 
+Redefine a :file:`admin/polymorphic/object_history.html` template, so it combines both worlds:
+
+.. code-block:: html+django
+
+    {% extends 'reversion/object_history.html' %}
+    {% load polymorphic_admin_tags %}
+
+    {% block breadcrumbs %}
+        {% breadcrumb_scope base_opts %}{{ block.super }}{% endbreadcrumb_scope %}
+    {% endblock %}
+
+This makes sure both the reversion template is used, and the breadcrumb is corrected for the polymorphic model.
+
 .. _django-reversion-compare-support:
 
 django-reversion-compare support

polymorphic/admin.py

@@ -525,6 +525,25 @@ class PolymorphicChildModelAdmin(admin.ModelAdmin):
             "admin/delete_confirmation.html"
         ]
 
+    @property
+    def object_history_template(self):
+        opts = self.model._meta
+        app_label = opts.app_label
+
+        # Pass the base options
+        base_opts = self.base_model._meta
+        base_app_label = base_opts.app_label
+
+        return [
+            "admin/%s/%s/object_history.html" % (app_label, opts.object_name.lower()),
+            "admin/%s/object_history.html" % app_label,
+            # Added:
+            "admin/%s/%s/object_history.html" % (base_app_label, base_opts.object_name.lower()),
+            "admin/%s/object_history.html" % base_app_label,
+            "admin/polymorphic/object_history.html",
+            "admin/object_history.html"
+        ]
+
     def render_change_form(self, request, context, add=False, change=False, form_url='', obj=None):
         context.update({
             'base_opts': self.base_model._meta,
@@ -537,6 +556,16 @@ class PolymorphicChildModelAdmin(admin.ModelAdmin):
         }
         return super(PolymorphicChildModelAdmin, self).delete_view(request, object_id, extra_context)
 
+    def history_view(self, request, object_id, extra_context=None):
+        # Make sure the history view can also display polymorphic breadcrumbs
+        context = {
+            'base_opts': self.base_model._meta,
+        }
+        if extra_context:
+            context.update(extra_context)
+        return super(PolymorphicChildModelAdmin, self).history_view(request, object_id, extra_context=context)
+
+
     # ---- Extra: improving the form/fieldset default display ----
 
     def get_fieldsets(self, request, obj=None):

polymorphic/templates/admin/polymorphic/object_history.html

@@ -0,0 +1,6 @@
+{% extends "admin/object_history.html" %}
+{% load polymorphic_admin_tags %}
+
+{% block breadcrumbs %}
+  {% breadcrumb_scope base_opts %}{{ block.super }}{% endbreadcrumb_scope %}
+{% endblock %}