Fixed #30736 -- Added Storage.get_alternative_name() to allow customization.

docs/howto/custom-file-storage.txt

@@ -97,6 +97,12 @@ non-standard characters are converted to safe filenames.
 The code provided on ``Storage`` retains only alpha-numeric characters, periods
 and underscores from the original filename, removing everything else.
 
+.. method:: get_alternative_name(file_root, file_ext)
+
+Returns an alternative filename based on the ``file_root`` and ``file_ext``
+parameters. By default, an underscore plus a random 7 character alphanumeric
+string is appended to the filename before the extension.
+
 .. method:: get_available_name(name, max_length=None)
 
 Returns a filename that is available in the storage mechanism, possibly taking
@@ -108,5 +114,5 @@ The length of the filename will not exceed ``max_length``, if provided. If a
 free unique filename cannot be found, a :exc:`SuspiciousFileOperation
 <django.core.exceptions.SuspiciousOperation>` exception is raised.
 
-If a file with ``name`` already exists, an underscore plus a random 7 character
-alphanumeric string is appended to the filename before the extension.
+If a file with ``name`` already exists, ``get_alternative_name()`` is called to
+obtain an alternative name.

docs/ref/files/storage.txt

@@ -105,6 +105,12 @@ The ``Storage`` class
         If :setting:`USE_TZ` is ``True``, returns an aware ``datetime``,
         otherwise returns a naive ``datetime`` in the local timezone.
 
+    .. method:: get_alternative_name(file_root, file_ext)
+
+        Returns an alternative filename based on the ``file_root`` and
+        ``file_ext`` parameters, an underscore plus a random 7 character
+        alphanumeric string is appended to the filename before the extension.
+
     .. method:: get_available_name(name, max_length=None)
 
         Returns a filename based on the ``name`` parameter that's free and
@@ -116,9 +122,8 @@ The ``Storage`` class
         :exc:`SuspiciousFileOperation
         <django.core.exceptions.SuspiciousOperation>` exception will be raised.
 
-        If a file with ``name`` already exists, an underscore plus a random
-        7 character alphanumeric string is appended to the filename before
-        the extension.
+        If a file with ``name`` already exists, :meth:`get_alternative_name` is
+        called to obtain an alternative name.
 
     .. method:: get_created_time(name)
 

docs/releases/3.0.txt

@@ -227,7 +227,9 @@ Email
 File Storage
 ~~~~~~~~~~~~
 
-* ...
+* The new :meth:`.Storage.get_alternative_name` method allows customizing the
+  algorithm for generating filenames if a file with the uploaded name already
+  exists.
 
 File Uploads
 ~~~~~~~~~~~~