add support for lists in tags.items in set_tags_batch()

(check CHANGELOG.md for more information)

fixes GitHub issue #12 , code contributed by @davidorme in #12 (comment)

CHANGELOG.md

@@ -27,8 +27,11 @@ Date (Timezone)              | Version | Comment
 02/01/2020 05:09:43 PM (PST) | 0.4.1   | incorporated pull request #2 and #3 by ickc which added a "no_output" feature and an import for ujson if it's installed.  Thanks for the updates!
 04/09/2020 04:25:31 AM (PDT) | 0.4.2   | roll back 0.4.0's pyexiftool rename.  It appears there's no specific PEP to have to to name PyPI projects to be py<something>.  The only convention I found was https://www.python.org/dev/peps/pep-0423/#use-standard-pattern-for-community-contributions which I might look at in more detail
 04/09/2020 05:15:40 AM (PDT) | 0.4.3   | initial work of moving the exiftool.py into a directory preparing to break it down into separate files to make the codebase more manageable
-03/12/2021 01:37:30 PM (PDT) | 0.4.4   | no functional code changes.  Revamped the setup.py and related files to release to PyPI.  Added all necessary and recommended files into release
-03/12/2021 02:03:38 PM (PDT) | 0.4.5   | no functional code changes.  re-release with new version because I accidentally included the "test" package with the PyPI 0.4.4 release.  I deleted it instead of yanking or doing a post release this time... just bumped the version.  "test" folder renamed to "tests" as per convention, so the build will automatically ignore it
+03/12/2021 01:37:30 PM (PST) | 0.4.4   | no functional code changes.  Revamped the setup.py and related files to release to PyPI.  Added all necessary and recommended files into release
+03/12/2021 02:03:38 PM (PST) | 0.4.5   | no functional code changes.  re-release with new version because I accidentally included the "test" package with the PyPI 0.4.4 release.  I deleted it instead of yanking or doing a post release this time... just bumped the version.  "test" folder renamed to "tests" as per convention, so the build will automatically ignore it
+04/08/2021 03:38:46 PM (PDT) | 0.4.6   | added support for config files in constructor -- Merged pull request #7 from @asielen and fixed a bug referenced in the discussion https://github.com/sylikc/pyexiftool/pull/7
+04/19/2021 02:37:02 PM (PDT) | 0.4.7   | added support for writing a list of values in set_tags_batch() which allows setting individual keywords (and other tags which are exiftool lists) -- contribution from @davidorme referenced in issue https://github.com/sylikc/pyexiftool/issues/12#issuecomment-821879234
+
 
 On version changes, update setup.py to reflect version
 

exiftool/exiftool.py

@@ -663,6 +663,9 @@ def set_tags_batch(self, tags, filenames):
 		:py:meth:`execute()`.
 
 		It can be passed into `check_ok()` and `format_error()`.
+
+		tags items can be lists, in which case, the tag will be passed 
+		with each item in the list, in the order given
 		"""
 		# Explicitly ruling out strings here because passing in a
 		# string would lead to strange and hard-to-find errors
@@ -676,7 +679,15 @@ def set_tags_batch(self, tags, filenames):
 		params = []
 		params_utf8 = []
 		for tag, value in tags.items():
-			params.append(u'-%s=%s' % (tag, value))
+			# contributed by @daviddorme in https://github.com/sylikc/pyexiftool/issues/12#issuecomment-821879234
+			# allows setting things like Keywords which require separate directives 
+			# > exiftool -Keywords=keyword1 -Keywords=keyword2 -Keywords=keyword3 file.jpg
+			# which are not supported as duplicate keys in a dictionary
+			if isinstance(value, list):
+				for item in value:
+					params.append(u'-%s=%s' % (tag, item))
+			else:
+				params.append(u'-%s=%s' % (tag, value))
 
 		params.extend(filenames)
 		params_utf8 = [x.encode('utf-8') for x in params]

setup.py

@@ -30,7 +30,7 @@
 
 	# overview
 	name="PyExifTool",
-	version="0.4.5",
+	version="0.4.7",
 	license="GPLv3+/BSD",
 	url="http://github.com/sylikc/pyexiftool",
 	python_requires=">=2.6",