How to write a Pundit policy with 3 or statements?

Question

I have a Pundit policy that's working properly, but the way I've written it doesn't seem to be the "best" way to express this. It's a policy with three "or" statements. Here's the code:

def update?
  user.admin? or user.moderator? || user.id == @artist.user_id
end

What's another way I could write this? Or is this the best way to express this?

Out of curiosity, why do you mix `or` and `||`? What seems to be "not the best" about `a || b || c`? — jvillian, May 15 '18 at 16:01
I just did that to separate it visually because admin and moderator are similar — Lee McAlilly, May 15 '18 at 20:04
FWIW, the [ruby style guide](https://github.com/bbatsov/ruby-style-guide#no-and-or-or) suggests `or` is "banned" due to the "high probability of introducing subtle bugs". — jvillian, May 15 '18 at 20:08

jvillian · Answer 1 · 2018-05-15T20:51:04.463

2

BTW, you could do something like:

delegate *%w(admin? moderator?), to: :user

def user_artist?
  user == @artist.user
end

def update?
  admin? || moderator? || user_artist?
end

That seems pretty clean to me.

edited May 15 '18 at 20:51

answered May 15 '18 at 20:17

jvillian

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score 1 · Accepted Answer · answered May 15 '18 at 16:21

1

Two possible ways to: either

def update?
  user.admin_or_moderator? || user == @artist.user
end

admin_or_moderator? is just to say, it could be even something like privileged? and implement this method in your User model. Or

def update?
  %i(admin moderator).include?(user.role) || user == @artist.user
end

Here I'm guessing you have something like a role in your User model but that's the idea

answered May 15 '18 at 16:21

Ursus

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would it be better to put `admin_or_moderator` in the user model or as a private method on the policy? – Lee McAlilly May 15 '18 at 20:05
it could makes sense even in the user model for me – Ursus May 15 '18 at 22:40

How to write a Pundit policy with 3 or statements?

2 Answers2