Looking for guidance on how I might model some relationships. Suppose I have a

foo

object and I am granting

view

permissions on a

foo

based on the visibility of the

foo

(where visibility is an application logic, and could be

only_me

,

friends

, or

everyone

. I have a sample schema that works

definition foo {
  relation token: token
  relation friends: foo

  // representing the visibility settings of `foo`. Only 1 of these relations should be logically set at any given time.
  relation viz_me: foo
  relation viz_friends: foo
  relation viz_everyone: token:*

  // intermediary results
  permission friends_tokens = friends->token

  permission view = (viz_everyone + viz_me->token + viz_friends->friends_tokens)
}

But it is a little bit clunky. Suppose for example that a

foo

is configured in the application as

only_me

visibility -- meaning that only tokens with the

token

relation can view it. If that changes to

friends

, then I need to: - Check if

viz_me

or

viz_everyone

is set, and un-set it - Set

viz_friends

relation This pattern is common in our application and so I'm looking for a way to effectively work with this pattern. Ideally, I'd like to set just one relation and update it with something that represents the set of tokens. I think that this would be possible if I could write a statement like this:

definition foo {
  relation token: token
  relation friends: foo

  relation viz_tokens: token

  permission view = viz_tokens
}

And set the

viz_tokens

, when writing the relationship, to something like

token:*

, or

$THIS->token

, or

$THIS->friends->token

. That way I get an atomic update, and don't need to worry about managing the fact that

Only 1 of these relations should be logically set at any given time.