Add JSON Schema and individual schema files

[psrpinto]

Fixes #134

This PR adds the ./schemas/ directory, but it is not used from anywhere yet.

The schemas can be validated with:

schemas/validate.mjs

Summary of changes

• Implement a script that validates all schemas under ./schemas/
• Define the JSON Schema
• Define the Schema of a blog post
• Define the Schema of a page
• Make the validation script ensure that there are no two schemas with the same slug

References

• Creating your first schema
• Get started with JSON Schema in Node.js
• https://ajv.js.org

[psrpinto]

#146 does some of the same things as here but in a schema/ directory, while here we're adding to schemas/. I deliberately added it to a different directory than #146, so that we can merge both PRs. Then I can open a new PR that integrates the two.

[ashfame]

Looks good!

[ashfame]

We decided on SubjectType enum to have dash as opposed to underscore earlier, we should keep both consistent, whatever that is. Personally, I think dash is better in all contexts where we might display it to the user or have it in the url?

[akirk]

I think we should use what's allowed via the custom post types allowed in WordPress: https://developer.wordpress.org/reference/functions/register_post_type/

Post type key. Must not exceed 20 characters and may only contain lowercase alphanumeric characters, dashes, and underscores. See sanitize_key() .

If we say we do 4 letter prefixes this would leave 16 chars of the above and we can do dashes instead of underscores.

[psrpinto]

Ok, I've made it so that dashes are accepted (underscores are not), and I've limited the length to 16 characters. This would mean that the post_type prefix that we use must not exceed 4 characters, for example twp_. If we end up using a longer prefix, we need to reduce the max length accordingly.

[akirk]

Looks good! I just added a couple of notes and noticed that we are mixing spaces and tabs indentation, I believe the JSON files can be tab indented as well.

[akirk]

Great, thank you!