Parse permalinks placeholders from markdown files name

[chawyehsu]

Just like what Hexo does.

saber-config.yml

permalinks:
  post: /posts/:year/:month/:day/:slug.html

./pages/_posts/2019-03-24-hello-saber.md

---
layout: post
date: 2019-03-24
---

Expect:

./pages/_posts/2019-03-24-hello-saber.md becomes /posts/2019/03/24/hello-saber.html

Actual:

./pages/_posts/2019-03-24-hello-saber.md becomes /posts/2019/03/24/2019-03-24-hello-saber.html

[egoist]

Nice we just need to extract the date from filename and use it as the default value of page.attributes.createdAt 👌

[chawyehsu]

Proposal:

A new saber config property: postName with the default value: :title.md. The :slug of a post is :title by default.

When users define postName to :year-:month-:day-:title.md, extract date :year-:month-:day as attributes.createdAt, and :title as:slug.

Similar to Hexo: https://github.com/hexojs/hexo/blob/087b3fa456aa97279df61a7f05e59c932051ee2b/lib/plugins/processor/post.js#L49-L54

[chawyehsu]

Another way is making a common page filename format with a built-in regex, inspired by zola.

Another exception to that rule is that a filename starting with a datetime (YYYY-mm-dd or a RFC3339 datetime) followed by an underscore (_) or a dash (-) will use that date as the page date, unless already set in the front-matter. The page name will be anything after _/- so a filename like 2018-10-10-hello-world.md will be available at [base_url]/hello-world. Note that the full RFC3339 datetime contains colons, which is not a valid character in a filename on Windows. —— zola doc

In this way, no extra postName config property needed, page filename format becomes strict but still behaves the same way as Hexo.

[egoist]

we have the permalinks option https://saberjs.org/docs/permalinks.html#placeholders

[chawyehsu]

Yeah, I know that option. What I want to say is that we need a way to detech whether the filename contains datetime or not, thus I provide two methods to do so. One is customizable and the other is strict. I prefer the latter, and will try to implement it.