Fix filter validation for field functions

[paescuj]

Scope

TIL the JSON count filter is broken since v9.14.4 (🤯):

This roots back to the filter validation not accounting for field functions (count(json_field)). Fortunately, this was not an issue for functions on relations (count(...)) or dates (year(...)), since the allowed operators for the fields itself and corresponding functions overlap there.

The filter validation has now been adjusted to properly check for:

• allowed functions on a field (e.g. count on JSON field)
• allowed filter type / operators (e.g. integer / _eq for count function) when using functions

Still works for relations and dates:

Potential Risks / Drawbacks

None, only bug fixing

Review Notes / Questions

Can be tested via Data Studio or API:

• REST:

   ?filter[count(json_field)][_eq]=1

• GraphQL:

  query {
    test(filter: { json_field_func: { count: { _eq: 1 } } }) {
      id
      json_field_func {
        count
      }
    }
  }

[changeset-bot]

🦋 Changeset detected

Latest commit: 9f94c06

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@directus/api	Patch
directus	Patch

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[hanneskuettner]

Very clean changes!