[pp:directory] add 'directory' post processor (#7432)

docs/configuration.rst

@@ -6440,6 +6440,19 @@ Description
     Only compare file sizes. Do not read and compare their content.
 
 
+directory.event
+---------------
+Type
+    * ``string``
+    * ``list`` of ``strings``
+Default
+    ``"prepare"``
+Description
+    The event(s) for which directory_ format strings are (re)evaluated.
+
+    See `metadata.event`_ for a list of available events.
+
+
 exec.archive
 ------------
 Type
@@ -7738,6 +7751,8 @@ Description
     ``compare``
         | Compare versions of the same file and replace/enumerate them on mismatch
         | (requires `downloader.*.part`_ = ``true`` and `extractor.*.skip`_ = ``false``)
+    ``directory``
+        Reevaluate directory_ format strings
     ``exec``
         Execute external commands
     ``hash``

gallery_dl/postprocessor/__init__.py

@@ -11,6 +11,7 @@
 modules = [
     "classify",
     "compare",
+    "directory",
     "exec",
     "hash",
     "metadata",

gallery_dl/postprocessor/directory.py

@@ -0,0 +1,30 @@
+# -*- coding: utf-8 -*-
+
+# Copyright 2025 Mike Fährmann
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 as
+# published by the Free Software Foundation.
+
+"""Trigger directory format string evaluation"""
+
+from .common import PostProcessor
+
+
+class DirectoryPP(PostProcessor):
+
+    def __init__(self, job, options):
+        PostProcessor.__init__(self, job)
+
+        events = options.get("event")
+        if events is None:
+            events = ("prepare",)
+        elif isinstance(events, str):
+            events = events.split(",")
+        job.register_hooks({event: self.run for event in events}, options)
+
+    def run(self, pathfmt):
+        pathfmt.set_directory(pathfmt.kwdict)
+
+
+__postprocessor__ = DirectoryPP

test/test_postprocessor.py

@@ -173,6 +173,24 @@ class ClassifyTest(BasePostprocessorTest):
         self.assertEqual(self.pathfmt.realpath, path + "/file.foo")
 
 
+class DirectoryTest(BasePostprocessorTest):
+
+    def test_default(self):
+        self._create()
+
+        path = os.path.join(self.dir.name, "test")
+        self.assertEqual(self.pathfmt.realdirectory, path + "/")
+        self.assertEqual(self.pathfmt.realpath, path + "/file.ext")
+
+        self.pathfmt.kwdict["category"] = "custom"
+        self._trigger()
+
+        path = os.path.join(self.dir.name, "custom")
+        self.assertEqual(self.pathfmt.realdirectory, path + "/")
+        self.pathfmt.build_path()
+        self.assertEqual(self.pathfmt.realpath, path + "/file.ext")
+
+
 class ExecTest(BasePostprocessorTest):
 
     def test_command_string(self):