Fix posts metadata to migrate from Jekyll to Blogdown

jekyll_blogdown_migrate_posts.md

#!/usr/bin/env python

import os
from pathlib import Path
import datetime
import frontmatter

posts_root = os.environ['HOME'] / Path('dev/brainblog/content/post')

for post in posts_root.iterdir():
    fname_date = post.name[0:10] # capture the "2018-02-08" "timestamp" from the post filename
    tstamp = datetime.datetime.strptime(fname_date, "%Y-%m-%d").timestamp()
    utc_time = datetime.datetime.utcfromtimestamp(tstamp)
    utc_string = utc_time.strftime("%Y-%m-%dT%H:%M:%S.%f+00:00")
    with post.open('r') as f:
        post_fm = frontmatter.load(f)
        if not post_fm.get('date'):
            post_fm.__setitem__('date', utc_string)
            post_fm.__setitem__('modified', utc_string)
            post_str = frontmatter.dumps(post_fm)
            f.close()

            with post.open('w') as f:
                f.write(post_str)