rules_compression.md

Rules compressions

Your rules are optimized automatically at runtime. There are a set of "rules" to optimize your rules definition and they are implemented in the RulesCompressor class. Here you can see how this works:

A rule without conditions is defined as catch_all.

A catch_all rule, eliminates all previous rules and all subsequent rules of the same type

can :read, Book, author_id: user.id
cannot :read, Book, private: true
can :read, Book
can :read, Book, id: 1
cannot :read, Book, private: true

becomes

can :read, Book
cannot :read, Book, private: true

If a catch_all cannot rule is first, it can be removed

cannot :read, Book
can :read, Book, author_id: user.id

becomes

can :read, Book, author_id: user.id

If all rules are cannot rules, this is equivalent to no rules

cannot :read, Book, private: true

becomes

# nothing

These optimizations allow you to follow the strategy of "Give Permissions, don't take them" and automatically ignore previous rules when they are not needed.