Strict frontmatter validation

[slorber]

🚀 Feature

We should validate docs/blog/pages frontmatter against a Joi schema:

• prevent the user to use bad frontmatter
• display friendly error messages when this happens
• allow unknown frontmatter (user can assign additional metadata to each doc)
• unit-test this validation logic
• try to use the frontmatter TS types in the theme?

Some initial work has been done in #4590 for Docs and Blog, but is not exhaustive as it was not really the point of this PR.

Asking for help from the community to get this work completed in a more exhaustive and polished way.

Please claim this issue if you are willing to help.

[ChayceJRoss]

I'd be willing to help with this.
Is the union of these - https://docusaurus.io/docs/api/plugins/@docusaurus/plugin-content-docs#markdown-frontmatter and https://docusaurus.io/docs/blog#header-options a full list of frontmatter options?

[Joshverge]

@slorber I'd like to help!

[slorber]

As we have 2 volunteers, I suggest:

• @ChayceJRoss works on docs: packages/docusaurus-plugin-content-docs/src/docFrontMatter.ts
• @Joshverge works on blog: packages/docusaurus-plugin-content-blog/src/blogFrontMatter.ts

Can you please review each-others and make sure both PRs have some kind of consistency and similar test structure?

Yes @ChayceJRoss those are the exhaustive list of frontmatter options to support

[jakehsiao]

I'd like to help too, where I can grab?

[slorber]

@jakehsiao we can't split more the work than it is already.
If we don't have news from @ChayceJRoss and @Joshverge under 7 days we'll assign that to you.

[Joshverge]

@slorber maybe @jakehsiao could grab the work assigned to me? I haven't been able to make much progress since I'm a beginner at ts/js

[ywjr]

After testing again, the title in the MD file cannot be empty. If it is empty, an error will appear.

In addition, when the title field in the MD file is Chinese, there is no problem

[ywjr]

I don't think it's a bug, but it's suggested to give which document's title is empty. Thank you

[slorber]

Ah I see, so you had something like title: right?
What was your motivation to have an empty title like that?

[ywjr]

yes ，like title： ， when i write md doc file in Chinese， i think ​the font size of the title is too large on md doc page ， but I can't change it， so i make title empty 。the font size of the title, H1, H2, H3, etc. can be modified by the user?

[slorber]

@ywjr let's track the too strict validation of title/description here #4652

You can definitively change the default style/font-size of the title through many ways: custom css, swizzling, providing a MDX h1 component... all these are documented.

[nam-hle]

I see two our assignees can't arrange enough time to work. Can I take some job here? 😁

[ywjr]

Yeah, I'm looking forward to your help,

…

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[slorber]

please go ahead @nam-hle , as others didn't make any progress