add option to specify additional key-value pairs

docs/configuration.rst

@@ -344,6 +344,15 @@ Description User-Agent header value to be used for HTTP requests.
 =========== =====
 
 
+extractor.*.keywords
+--------------------
+=========== =====
+Type        ``object``
+Example    ``{"type": "Pixel Art", "type_id": 123}``
+Description Additional key-value pairs to be added to each metadata dictionary.
+=========== =====
+
+
 Extractor-specific Options
 ==========================
 

gallery_dl/__init__.py

@@ -100,7 +100,7 @@ def parse_inputfile(file):
             continue
 
         elif line[0] == "{":
-            # url-specfic config spec
+            # url-specific config spec
             try:
                 cfd = json.loads(line)
             except ValueError as exc:

gallery_dl/job.py

@@ -52,6 +52,9 @@ class Job():
             self.extractor.category = parent.extractor.category
             self.extractor.subcategory = parent.extractor.subcategory
 
+        # user-supplied metadata
+        self.userkwds = self.extractor.config("keywords")
+
     def run(self):
         """Execute or run the job"""
         try:
@@ -133,9 +136,11 @@ class Job():
         """Handle Message.Queue"""
 
     def update_kwdict(self, kwdict):
-        """Add 'category' and 'subcategory' keywords"""
+        """Update 'kwdict' with additional metadata"""
         kwdict["category"] = self.extractor.category
         kwdict["subcategory"] = self.extractor.subcategory
+        if self.userkwds:
+            kwdict.update(self.userkwds)
 
     def _write_unsupported(self, url):
         if self.ufile: