Fixed #19721 -- Allowed admin filters to customize the list separator.

2 files changed, 23 insertions, 0 deletions

diff --git a/docs/ref/contrib/admin/filters.txt b/docs/ref/contrib/admin/filters.txt
index f78005936d..0dc119af3f 100644
--- a/docs/ref/contrib/admin/filters.txt
+++ b/docs/ref/contrib/admin/filters.txt
@@ -176,6 +176,25 @@ allows to store::
             ('title', admin.EmptyFieldListFilter),
         )
 
+By defining a filter using the ``__in`` lookup, it is possible to filter for
+any of a group of values. You need to override the ``expected_parameters``
+method, and the specify the ``lookup_kwargs`` attribute with the appropriate
+field name. By default, multiple values in the query string will be separated
+with commas, but this can be customized via the ``list_separator`` attribute.
+The following example shows such a filter using the vertical-pipe character as
+the separator::
+
+    class FilterWithCustomSeparator(admin.FieldListFilter):
+        # custom list separator that should be used to separate values.
+        list_separator = '|'
+
+        def __init__(self, field, request, params, model, model_admin, field_path):
+            self.lookup_kwarg = '%s__in' % field_path
+            super().__init__(field, request, params, model, model_admin, field_path)
+
+        def expected_parameters(self):
+            return [self.lookup_kwarg]
+
 .. note::
 
     The :class:`~django.contrib.contenttypes.fields.GenericForeignKey` field is
diff --git a/docs/releases/4.1.txt b/docs/releases/4.1.txt
index 543c9caf6e..c55e638695 100644
--- a/docs/releases/4.1.txt
+++ b/docs/releases/4.1.txt
@@ -54,6 +54,10 @@ Minor features
 * The admin :ref:`dark mode CSS variables <admin-theming>` are now applied in a
   separate stylesheet and template block.
 
+* :ref:`modeladmin-list-filters` providing custom ``FieldListFilter``
+  subclasses can now control the query string value separator when filtering
+  for multiple values using the ``__in`` lookup.
+
 :mod:`django.contrib.admindocs`
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~