[postprocessor:mtime] add 'value' option (#2739)

docs/configuration.rst

@@ -3464,6 +3464,24 @@ Description
     This value must either be a UNIX timestamp or a
     |datetime|_ object.
 
+    Note: This option gets ignored if `mtime.value`_ is set.
+
+
+mtime.value
+-----------
+Type
+    ``string``
+Default
+    ``null``
+Example
+    * ``"{status[date]}"``
+    * ``"{content[0:6]:R22/2022/D%Y%m%d/}"``
+Description
+    A `format string`_ whose value should be used.
+
+    The resulting value must either be a UNIX timestamp or a
+    |datetime|_ object.
+
 
 ugoira.extension
 ----------------

gallery_dl/postprocessor/mtime.py

@@ -9,7 +9,7 @@
 """Use metadata as file modification time"""
 
 from .common import PostProcessor
-from .. import text, util
+from .. import text, util, formatter
 from datetime import datetime
 
 
@@ -17,7 +17,12 @@ class MtimePP(PostProcessor):
 
     def __init__(self, job, options):
         PostProcessor.__init__(self, job)
-        self.key = options.get("key", "date")
+        value = options.get("value")
+        if value:
+            self._get = formatter.parse(value, None, util.identity).format_map
+        else:
+            key = options.get("key", "date")
+            self._get = lambda kwdict: kwdict.get(key)
 
         events = options.get("event")
         if events is None:
@@ -27,7 +32,7 @@ class MtimePP(PostProcessor):
         job.register_hooks({event: self.run for event in events}, options)
 
     def run(self, pathfmt):
-        mtime = pathfmt.kwdict.get(self.key)
+        mtime = self._get(pathfmt.kwdict)
         pathfmt.kwdict["_mtime"] = (
             util.datetime_to_timestamp(mtime)
             if isinstance(mtime, datetime) else

test/test_postprocessor.py

@@ -350,10 +350,6 @@ class MetadataTest(BasePostprocessorTest):
 
 class MtimeTest(BasePostprocessorTest):
 
-    def test_mtime_default(self):
-        pp = self._create()
-        self.assertEqual(pp.key, "date")
-
     def test_mtime_datetime(self):
         self._create(None, {"date": datetime(1980, 1, 1)})
         self._trigger()
@@ -364,11 +360,16 @@ class MtimeTest(BasePostprocessorTest):
         self._trigger()
         self.assertEqual(self.pathfmt.kwdict["_mtime"], 315532800)
 
-    def test_mtime_custom(self):
+    def test_mtime_key(self):
         self._create({"key": "foo"}, {"foo": 315532800})
         self._trigger()
         self.assertEqual(self.pathfmt.kwdict["_mtime"], 315532800)
 
+    def test_mtime_value(self):
+        self._create({"value": "{foo}"}, {"foo": 315532800})
+        self._trigger()
+        self.assertEqual(self.pathfmt.kwdict["_mtime"], 315532800)
+
 
 class ZipTest(BasePostprocessorTest):