Support for relationships from nested action fields

[sordina]

Is your proposal related to a problem?

With the addition of support for nested types in actions: (#4796) the next logical functionality is to add support for joining across relationships from within nested fields.

Describe the solution you'd like

If a relationship is established from an associated action type that should be able to be traversed via field selection as with a normal GraphQL query. This would include fields within objects, arrays to arbitrary levels of nesting.

Drawbacks

Particularly tricky scenarios include the following:

• Joins across actions
• How to ensure the optimal amount of logic is performed in the DB
• Lazily traversing fields so that self/co-recursive relationships don't cause infinite loops

Describe alternatives you've considered

Currently we only support relationships from top-level fields.

If the feature is approved, would you be willing to submit a PR?

Yes.