[postprocessor:metadata] add 'directory' option (#520)

docs/configuration.rst

@@ -1485,6 +1485,16 @@ Description Select how to write metadata.
               to a file's metadata dictionary
 =========== =====
 
+metadata.directory
+------------------
+=========== =====
+Type        ``string``
+Default     ``"."``
+Example     ``"metadata"``
+Description Directory where metadata files are stored in relative to the
+            current target location for file downloads.
+=========== =====
+
 metadata.extension
 ------------------
 =========== =====

gallery_dl/postprocessor/metadata.py

@@ -10,6 +10,7 @@
 
 from .common import PostProcessor
 from .. import util
+import os
 
 
 class MetadataPP(PostProcessor):
@@ -32,32 +33,46 @@ class MetadataPP(PostProcessor):
             self.ascii = options.get("ascii", False)
             ext = "json"
 
+        directory = options.get("directory")
+        if directory:
+            self._directory = self._directory_custom
+            sep = os.sep + (os.altsep or "")
+            self.metadir = directory.rstrip(sep) + os.sep
+
         extfmt = options.get("extension-format")
         if extfmt:
-            self.path = self._path_format
+            self._filename = self._filename_custom
             self.extfmt = util.Formatter(extfmt).format_map
         else:
-            self.path = self._path_append
             self.extension = options.get("extension", ext)
 
         if options.get("bypost"):
             self.run_metadata, self.run = self.run, self.run_metadata
 
     def run(self, pathfmt):
-        with open(self.path(pathfmt), "w", encoding="utf-8") as file:
+        path = self._directory(pathfmt) + self._filename(pathfmt)
+        with open(path, "w", encoding="utf-8") as file:
             self.write(file, pathfmt.kwdict)
 
-    def _path_append(self, pathfmt):
-        return "{}.{}".format(pathfmt.realpath, self.extension)
+    def _directory(self, pathfmt):
+        return pathfmt.realdirectory
 
-    def _path_format(self, pathfmt):
+    def _directory_custom(self, pathfmt):
+        directory = os.path.join(pathfmt.realdirectory, self.metadir)
+        os.makedirs(directory, exist_ok=True)
+        return directory
+
+    def _filename(self, pathfmt):
+        return pathfmt.filename + "." + self.extension
+
+    def _filename_custom(self, pathfmt):
         kwdict = pathfmt.kwdict
         ext = kwdict["extension"]
         kwdict["extension"] = pathfmt.extension
         kwdict["extension"] = pathfmt.prefix + self.extfmt(kwdict)
-        path = pathfmt.realdirectory + pathfmt.build_filename()
+        filename = pathfmt.build_filename()
         kwdict["extension"] = ext
-        return path
+        return filename
 
     def _write_custom(self, file, kwdict):
         file.write(self.contentfmt(kwdict))

test/test_postprocessor.py

@@ -7,6 +7,7 @@
 # it under the terms of the GNU General Public License version 2 as
 # published by the Free Software Foundation.
 
+import os
 import os.path
 import zipfile
 import tempfile
@@ -156,7 +157,6 @@ class MetadataTest(BasePostprocessorTest):
             "_private" : "world",
         })
 
-        self.assertEqual(pp.path     , pp._path_append)
         self.assertEqual(pp.write    , pp._write_json)
         self.assertEqual(pp.ascii    , True)
         self.assertEqual(pp.indent   , 2)
@@ -242,7 +242,7 @@ class MetadataTest(BasePostprocessorTest):
             "extension-format": "json",
         })
 
-        self.assertEqual(pp.path, pp._path_format)
+        self.assertEqual(pp._filename, pp._filename_custom)
 
         with patch("builtins.open", mock_open()) as m:
             pp.prepare(self.pathfmt)
@@ -264,6 +264,31 @@ class MetadataTest(BasePostprocessorTest):
         path = self.pathfmt.realdirectory + "file.2.EXT-data:tESt"
         m.assert_called_once_with(path, "w", encoding="utf-8")
 
+    def test_metadata_directory(self):
+        pp = self._create({
+            "directory": "metadata",
+        })
+
+        with patch("builtins.open", mock_open()) as m:
+            pp.prepare(self.pathfmt)
+            pp.run(self.pathfmt)
+
+        path = self.pathfmt.realdirectory + "metadata/file.ext.json"
+        m.assert_called_once_with(path, "w", encoding="utf-8")
+
+    def test_metadata_directory_2(self):
+        pp = self._create({
+            "directory"       : "metadata////",
+            "extension-format": "json",
+        })
+
+        with patch("builtins.open", mock_open()) as m:
+            pp.prepare(self.pathfmt)
+            pp.run(self.pathfmt)
+
+        path = self.pathfmt.realdirectory + "metadata/file.json"
+        m.assert_called_once_with(path, "w", encoding="utf-8")
+
     @staticmethod
     def _output(mock):
         return "".join(