[common] use 'parent' value as 'parent-metadata' default (#8525 #8604)

enable 'parent-metadata' by default for
'chevereto' & 'imagehost' (album/gallery) extractors

docs/configuration.rst

@@ -231,10 +231,13 @@ Type
     * ``bool``
     * ``string``
 Default
+    ``true``
+        ``[chevereto]`` |
+        ``[imagehost]``
     ``false``
+        otherwise
 Description
-    If ``true``, overwrite any metadata provided by a child extractor
-    with its parent's.
+    Forward a parent's metadata to its child extractors.
 
     | If this is a ``string``, add a parent's metadata to its children's
       to a field named after said string.

docs/gallery-dl.conf

@@ -1007,6 +1007,11 @@
             "videos" : true
         },
 
+        "chevereto":
+        {
+            "parent-metadata": true
+        },
+
         "Danbooru":
         {
             "sleep-request": "0.5-1.5",
@@ -1076,6 +1081,11 @@
             "referer": false
         },
 
+        "imagehost":
+        {
+            "parent-metadata": true
+        },
+
         "mastodon":
         {
             "access-token": null,

gallery_dl/extractor/chevereto.py

@@ -17,6 +17,7 @@ class CheveretoExtractor(BaseExtractor):
     basecategory = "chevereto"
     directory_fmt = ("{category}", "{user}", "{album}")
     archive_fmt = "{id}"
+    parent = True
 
     def _init(self):
         self.path = self.groups[-1]

gallery_dl/extractor/common.py

@@ -33,6 +33,7 @@ class Extractor():
     basecategory = ""
     basesubcategory = ""
     categorytransfer = False
+    parent = False
     directory_fmt = ("{category}",)
     filename_fmt = "{filename}.{extension}"
     archive_fmt = ""

gallery_dl/extractor/imagehosts.py

@@ -19,6 +19,7 @@ class ImagehostImageExtractor(Extractor):
     basecategory = "imagehost"
     subcategory = "image"
     archive_fmt = "{token}"
+    parent = True
     _https = True
     _params = None
     _cookies = None

gallery_dl/job.py

@@ -452,7 +452,8 @@ class DownloadJob(Job):
             else:
                 extr._parentdir = pextr._parentdir
 
-            if pmeta := pextr.config2("parent-metadata", "metadata-parent"):
+            if pmeta := pextr.config2(
+                    "parent-metadata", "metadata-parent", pextr.parent):
                 if isinstance(pmeta, str):
                     data = self.kwdict.copy()
                     if kwdict: