Fixed #18388 - Added InlineModelAdmin.get_max_num hook.

Thanks d.willy.c.c@ for the suggestion and Melevir and Areski Belaid for work
on the patch.

2 files changed, 29 insertions, 2 deletions

diff --git a/docs/ref/contrib/admin/index.txt b/docs/ref/contrib/admin/index.txt
index 73ea74adc0..8f457e77ac 100644
--- a/docs/ref/contrib/admin/index.txt
+++ b/docs/ref/contrib/admin/index.txt
@@ -1728,6 +1728,11 @@ The ``InlineModelAdmin`` class adds:
     doesn't directly correlate to the number of objects, but can if the value
     is small enough. See :ref:`model-formsets-max-num` for more information.
 
+    .. versionadded:: 1.6
+
+    :meth:`InlineModelAdmin.get_max_num` also allows you to customize the
+    maximum number of extra forms.
+
 .. attribute:: InlineModelAdmin.raw_id_fields
 
     By default, Django's admin uses a select-box interface (<select>) for
@@ -1787,6 +1792,27 @@ The ``InlineModelAdmin`` class adds:
                     return extra - obj.binarytree_set.count()
                 return extra
 
+.. method:: InlineModelAdmin.get_max_num(self, request, obj=None, **kwargs)
+
+    .. versionadded:: 1.6
+
+    Returns the maximum number of extra inline forms to use. By default,
+    returns the :attr:`InlineModelAdmin.max_num` attribute.
+
+    Override this method to programmatically determine the maximum number of
+    inline forms. For example, this may be based on the model instance
+    (passed as the keyword argument ``obj``)::
+
+        class BinaryTreeAdmin(admin.TabularInline):
+            model = BinaryTree
+
+            def get_max_num(self, request, obj=None, **kwargs):
+                max_num = 10
+                if obj.parent:
+                    return max_num - 5
+                return max_num
+
+
 Working with a model with two or more foreign keys to the same parent model
 ---------------------------------------------------------------------------
 
diff --git a/docs/releases/1.6.txt b/docs/releases/1.6.txt
index cd665a775e..2dca61bfed 100644
--- a/docs/releases/1.6.txt
+++ b/docs/releases/1.6.txt
@@ -292,9 +292,10 @@ Minor features
   :meth:`~django.db.models.query.QuerySet.select_related` can be cleared using
   ``select_related(None)``.
 
-* The :meth:`~django.contrib.admin.InlineModelAdmin.get_extra` method on
+* The :meth:`~django.contrib.admin.InlineModelAdmin.get_extra` and
+  :meth:`~django.contrib.admin.InlineModelAdmin.get_max_num` methods on
   :class:`~django.contrib.admin.InlineModelAdmin` may be overridden to
-  customize the number of extra inline forms.
+  customize the extra and maximum number of inline forms.
 
 Backwards incompatible changes in 1.6
 =====================================