Frontmatterのカテゴリーをフラットな文字列から配列に置き換える。

update-frontmatter-categories.py

import os
import glob
import frontmatter

target_file = "*.markdown"
new_dir = "new/"

os.makedirs(new_dir, exist_ok=True)

for fname in glob.glob(target_file):
    print('start editing - ' + fname)
    with open(fname, 'r') as f:
        post = frontmatter.load(f)

        categories = post['categories']
        if categories is not None:
            if type(categories) is str:
                post['categories'] = categories.split(',')

        with open(new_dir + fname, 'wb') as nf:
            frontmatter.dump(post, nf)