Hello Rafael,
This is very do-able in Rails.
What you will need to do is something like:
Create models to hold your positions and permissions.
Then setup HABTM relationships using has_and_belongs_to_many
For Member class:
has_and_belongs_to_many :positions
For Position class:
has_and_belongs_to_many :members
has_and_belongs_to_many :permissions
For Permission class:
has_and_belongs_to_many :positions
Then create tables:
positions_users, positions, permissions_positions, permissions
Then setup:
function to be executed before actions where permissions check is required using before_filter where you actually check for permissions. In that function you will query the positions table and then check for permissions.
Hope this helps.
-- Frank
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