feat(blog): add LastUpdateAuthor & LastUpdateTime

[OzakIOne]

Pre-flight checklist

• I have read the Contributing Guidelines on pull requests.
• If this is a code change: I have written unit tests and/or added dogfooding pages to fully verify the new behavior.
• If this is a new API or substantial change: the PR has an accompanying issue (closes #0000) and the maintainers have approved on my working plan.

Motivation

Provide two options in blog showLastUpdateAuthor and showLastUpdateTime which like in docs, show the time the blog was last updated and also who updated it

blog: {
  path: 'blog',
  showLastUpdateAuthor: true,
  showLastUpdateTime: true,
}

Test Plan

• docusaurus-utils-validation/validationSchemas.test.ts => frontMatterLastUpdateSchema schema
• docusaurus-plugin-content-blog/index.test.ts => last update
• docusaurus-utils/lastUpdateUtils.test.ts => readLastUpdateData

Test links

Blog preview
Blog Content Documentation

Related issues/PRs

Fix #8657

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[github-actions]

⚡️ Lighthouse report for the deploy preview of this PR

URL	Performance	Accessibility	Best Practices	SEO	PWA	Report
/	🟠 73	🟢 98	🟢 96	🟢 100	🟠 88	Report
/docs/installation	🟠 67	🟢 96	🟢 100	🟢 100	🟠 88	Report
/docs/category/getting-started	🟠 75	🟢 100	🟢 100	🟢 90	🟠 88	Report
/blog	🟠 66	🟢 100	🟢 100	🟢 90	🟠 88	Report
/blog/preparing-your-site-for-docusaurus-v3	🟠 59	🟢 96	🟢 100	🟢 100	🟠 88	Report
/blog/tags/release	🟠 71	🟢 100	🟢 100	🟠 80	🟠 88	Report
/blog/tags	🟠 75	🟢 100	🟢 100	🟢 90	🟠 88	Report

[github-actions]

Size Change: +130 B (0%)

Total Size: 992 kB

Filename	Size	Change
website/build/assets/css/styles.********.css	114 kB	-64 B (0%)
website/build/assets/js/main.********.js	765 kB	+194 B (0%)

ℹ️ View Unchanged

Filename	Size
website/.docusaurus/globalData.json	75.4 kB
website/build/index.html	37.9 kB

_{compressed-size-action}

[slorber]

Looks like a good start 👍

We still need to:

• refactor, share code
• add tests
• implement a uniform footer design
• support structured data (Blog posts should be able to display last update date #8657 (comment))

[slorber]

I know this is the historical message, but honestly, I doubt users will understand it 😅

Not sure mentioning FileChange is super useful, we just need users to know they should provide a date or an author attribute.

[OzakIOne]

type FrontMatterLastUpdate = {
  author?: string;
  date?: Date | string;
};

As author seems to be only a string I wonder removing author key or an author object (with a key and/or name)

So it would be something like this :

const FrontMatterAuthorErrorMessage =
  '{{#label}} does not look like a valid blog post author. Please use a string (maybe insert example?).';

const FrontMatterLastUpdateErrorMessage =
  '{{#label}} does not look like a valid front matter date. Please use a string or date (maybe insert example?).';

[slorber]

As author seems to be only a string I wonder removing author key or an author object (with a key and/or name)

const FrontMatterAuthorErrorMessage =
 '{{#label}} does not look like a valid blog post author. Please use a string (maybe insert example?).';

I think you mislead blog post authors and last update author: those are different concepts

https://docusaurus.io/docs/api/plugins/@docusaurus/plugin-content-blog#authors

Blog post authors (not just a single one) can be objects, strings (keys)

  export type BlogPostFrontMatterAuthor = Author & {
    /**
     * Will be normalized into the `imageURL` prop.
     */
    image_url?: string;
    /**
     * References an existing author in the authors map.
     */
    key?: string;
  };

  export type BlogPostFrontMatterAuthors =
    | string
    | BlogPostFrontMatterAuthor
    | (string | BlogPostFrontMatterAuthor)[];

Only the last update author is just a string, so your new validation error message proposal is not good.

---

const FrontMatterLastUpdateErrorMessage =
  '{{#label}} does not look like a valid front matter date. Please use a string or > date (maybe insert example?).';

Not good either, the last update is not a "date", but an object that can have either (or both) a date attribute (Date | string) and an author (string) attribute.

The message doesn't have to explain the types IMHO, just mention that the overall object shape is wrong and valid attribute names. Yaml will auto-convert strings to Dates depending on the format so mentioning it accept both Date + string is kind of overkill.

[slorber]

👍 good progress