Search: facet/filter by metadata, e.g. `tags` or `categories`

[albtam]

Description

Today, it is possible to filter search results "by tag" with the following syntax: +<my_tag> my_query>. Note: this is not completely correct as all the documents that contain my_tag will be returned not only the ones that define this tag.

For users, it requires 2 things:

1. They should know the available tags
2. They should know how to filter "by tag"

Providing a menu where you can select the tags (so you immediately see the available tags) would be more user-friendly

Use Cases

For large documentation, the search functionality could take part of the tag system to make it easier to filter the results avoiding having too many results in one view

Visuals

As an example, see the search bar UI of this website (powered by Algolia). On the left, there is a menu with the available tags

Note: FYI I found this old issue to integrate DocSearch into the mkdocs-search plugin

Before submitting

• I have read and followed the change request guidelines.
• I have verified that my idea is a change request and not a bug report.
• I have ensured that, to the best knowledge, my idea will benefit the entire community.
• I have included relevant links to the documentation, related issues and discussions to underline the need for my idea.

[squidfunk]

I've started working on the next big search update which will include the ability to list and better select available metadata like tags, authors, etc. This will allow to customize the search in a way that wasn't possible before.

[squidfunk]

Please see the announcement in #6307.

[squidfunk]

This change request is now part of our brand new backlog, which means it is considered for implementation once we move out of feature freeze. As by our new approach to manage change request, it will be closed in the meantime. Also, please see:

• Backlog: see open change requests #8200