[postprocessor:metadata] add 'tags' and 'custom' modes (#135)

docs/configuration.rst

@@ -1083,6 +1083,44 @@ Description The command to run.
 =========== =====
 
 
+metadata
+--------
+
+Write image metadata to separate files
+
+metadata.mode
+-------------
+=========== =====
+Type        ``string``
+Default     ``"json"``
+Description Select how to write metadata.
+
+            - ``"json"``: all metadata using `json.dump()
+              <https://docs.python.org/3/library/json.html#json.dump>`_
+            - ``"tags"``: ``tags`` separated by newlines
+            - ``"custom"``: result of applying `metadata.format`_ to a file's
+              metadata dictionary
+=========== =====
+
+metadata.extension
+------------------
+=========== =====
+Type        ``string``
+Default     ``"json"`` or ``"txt"``
+Description Filename extension for metadata files.
+=========== =====
+
+metadata.format
+---------------
+=========== =====
+Type        ``string``
+Example     ``"tags:\n\n{tags:J\n}\n"``
+Description Custom format string to build content of metadata files.
+
+            Note: Only applies for ``"mode": "custom"``.
+=========== =====
+
+
 ugoira
 ------
 

gallery_dl/postprocessor/metadata.py

@@ -9,6 +9,7 @@
 """Write metadata to JSON files"""
 
 from .common import PostProcessor
+from .. import util
 import json
 
 
@@ -16,18 +17,57 @@ class MetadataPP(PostProcessor):
 
     def __init__(self, pathfmt, options):
         PostProcessor.__init__(self)
-        self.indent = options.get("indent", 4)
-        self.ascii = options.get("ascii", False)
+
+        mode = options.get("mode", "json")
+        ext = "txt"
+
+        if mode == "custom":
+            self.write = self._write_custom
+            self.formatter = util.Formatter(options.get("format"))
+        elif mode == "tags":
+            self.write = self._write_tags
+        else:
+            self.write = self._write_json
+            self.indent = options.get("indent", 4)
+            self.ascii = options.get("ascii", False)
+            ext = "json"
+
+        self.extension = options.get("extension", ext)
 
     def run(self, pathfmt):
-        with open(pathfmt.realpath + ".json", "w") as file:
-            json.dump(
-                pathfmt.keywords,
-                file,
-                sort_keys=True,
-                indent=self.indent,
-                ensure_ascii=self.ascii,
-            )
+        path = "{}.{}".format(pathfmt.realpath, self.extension)
+        with open(path, "w", encoding="utf-8") as file:
+            self.write(file, pathfmt)
+
+    def _write_custom(self, file, pathfmt):
+        output = self.formatter.format_map(pathfmt.keywords)
+        file.write(output)
+
+    def _write_tags(self, file, pathfmt):
+        kwds = pathfmt.keywords
+        tags = kwds.get("tags") or kwds.get("tag_string")
+
+        if not tags:
+            return
+
+        if not isinstance(tags, list):
+            for separator in (" :: ", ", ", " "):
+                taglist = tags.split(separator)
+                if len(taglist) >= len(tags) / 16:
+                    break
+            tags = taglist
+
+        file.write("\n".join(tags))
+        file.write("\n")
+
+    def _write_json(self, file, pathfmt):
+        json.dump(
+            pathfmt.keywords,
+            file,
+            sort_keys=True,
+            indent=self.indent,
+            ensure_ascii=self.ascii,
+        )
 
 
 __postprocessor__ = MetadataPP