Allow an unknown principal, resource or action to be constrained to a certain entity type

[B-Lorentz]

Category

User level API features/changes

Describe the feature you'd like to request

Allow the caller to create a request with an unknown principal or resource, that is still known to belong to a certain type.

This is enroaching on the open rfc of https://github.com/cedar-policy/rfcs/pull/83/files
but I found it to be very useful for a 'query construction' usecase, similar to the one outlined here:
https://cedarland.blog/usage/partial-evaluation/content.html#what-can-alice-access

Describe alternatives you've considered

Without this, the only way to remove from the residual policies which are clearly excluded by the scope is to construct a full dummy entity ID of the right type, and then insert into the entity store an entry with that id.
But this requires all the fields of the entity to be explicitly set to 'unknown', and makes the evaluator assume the entity has no parents (since the parents of a concrete entity can't be unknown atm)

Additional context

No response

Is this something that you'd be interested in working on?

• 👋 I may be able to implement this feature request
• ⚠️ This feature might incur a breaking change

[cdisselkoen]

This is a special case of #812

[B-Lorentz]

This is a special case of #812

I would even say it's a duplicate. I tried to search if there is a similar issue already, but somehow overlooked that one

[shaobo-he-aws]

That being said, I still think #1391 is helpful. Let's close this issue in favor of #812 and keep the PR.