Fixed #24474 -- Allowed configuring the admin's empty change list value.

docs/ref/contrib/admin/index.txt

@@ -205,6 +205,33 @@ subclass::
         to its documentation for some caveats when time zone support is
         enabled (:setting:`USE_TZ = True <USE_TZ>`).
 
+.. attribute:: ModelAdmin.empty_value_display
+
+    .. versionadded:: 1.9
+
+    This attribute overrides the default display value for record's fields that
+    are empty (``None``, empty string, etc.). The default value is ``-`` (a
+    dash). For example::
+
+        from django.contrib import admin
+
+        class AuthorAdmin(admin.ModelAdmin):
+            empty_value_display = '-empty-'
+
+    You can also override ``empty_value_display`` for all admin pages with
+    :attr:`AdminSite.empty_value_display`, or for specific fields like this::
+
+        from django.contrib import admin
+
+        class AuthorAdmin(admin.ModelAdmin):
+            fields = ('name', 'title', 'view_birth_date')
+
+            def view_birth_date(self, obj):
+                return obj.birth_date
+
+            view_birth_date.short_name = 'birth_date'
+            view_birth_date.empty_value_display = '???'
+
 .. attribute:: ModelAdmin.exclude
 
     This attribute, if given, should be a list of field names to exclude from
@@ -583,6 +610,33 @@ subclass::
           class PersonAdmin(admin.ModelAdmin):
               list_display = ('first_name', 'last_name', 'colored_name')
 
+    * If the value of a field is ``None``, an empty string, or an iterable
+      without elements, Django will display ``-`` (a dash). You can override
+      this with :attr:`AdminSite.empty_value_display`::
+
+          from django.contrib import admin
+
+          admin.site.empty_value_display = '(None)'
+
+      You can also use :attr:`AdminSite.empty_value_display`::
+
+          class PersonAdmin(admin.ModelAdmin):
+              empty_value_display = 'unknown'
+
+      Or on a field level::
+
+          class PersonAdmin(admin.ModelAdmin):
+              list_display = ('name', 'birth_date_view')
+
+              def birth_date_view(self, obj):
+                   return obj.birth_date
+
+              birth_date_view.empty_value_display = 'unknown'
+
+      .. versionadded:: 1.9
+
+          The ability to customize ``empty_value_display`` was added.
+
     * If the string given is a method of the model, ``ModelAdmin`` or a
       callable that returns True or False Django will display a pretty
       "on" or "off" icon if you give the method a ``boolean`` attribute
@@ -604,7 +658,6 @@ subclass::
           class PersonAdmin(admin.ModelAdmin):
               list_display = ('name', 'born_in_fifties')
 
-
     * The ``__str__()`` (``__unicode__()`` on Python 2) method is just
       as valid in ``list_display`` as any other model method, so it's
       perfectly OK to do this::
@@ -2468,6 +2521,16 @@ Templates can override or extend base admin templates as described in
 
     Path to a custom template that will be used by the admin site app index view.
 
+.. attribute:: AdminSite.empty_value_display
+
+    .. versionadded:: 1.9
+
+    The string to use for displaying empty values in the admin site's change
+    list. Defaults to a dash. The value can also be overridden on a per
+    ``ModelAdmin`` basis and on a custom field within a ``ModelAdmin`` by
+    setting an ``empty_value_display`` attribute on the field. See
+    :attr:`ModelAdmin.empty_value_display` for examples.
+
 .. attribute:: AdminSite.login_template
 
     Path to a custom template that will be used by the admin site login view.

docs/releases/1.9.txt

@@ -48,6 +48,13 @@ Minor features
   changing the ``select_related()`` values used in the admin's changelist query
   based on the request.
 
+* :attr:`AdminSite.empty_value_display
+  <django.contrib.admin.AdminSite.empty_value_display>` and
+  :attr:`ModelAdmin.empty_value_display
+  <django.contrib.admin.ModelAdmin.empty_value_display>` were added to override
+  the display of empty values in admin change list. You can also customize the
+  value for each field.
+
 :mod:`django.contrib.auth`
 ^^^^^^^^^^^^^^^^^^^^^^^^^^