Question

I have three models, one for Projects, other for Users and other to the has_many :through called Projectzation.

The Projectzation migration looks like this

class CreateProjectzations < ActiveRecord::Migration
  def change
    create_table :projectzations do |t|
      t.references :user, :project
      t.boolean :admin
      t.timestamps
    end
  end
end

Then, to create the association i do like this

user.projectzation.create(:project => project, :admin => true)

By setting admin=true, I say that the user is an adminstrator of the project.

How to know if the user is an adminstrator? Maybe something like this

project.is_admin_user?(@current_user)

Answer 1

has_many :through is here a m:n relationship between projects and users. So the question has to be all the time: “Is a user an admin user for a project?”

So your call project.is_admin_user?(@current_user) (in the context of UsersController) is meaningful.

A possible implementation could be:

class Project ...
  def is_admin_user?(user)
    user.projectzations.detect{|p| p.project == self && p.admin?} != nil
  end
end

You could add

class User ...
  def is_admin_user_for?(project)
    project.is_admin_user?(self)
  end
end

so it could be asked in both directions.

In my opinion, there are three cases:

1. The user has no relationship to the project.
2. The user has a relationship to the project, but is no admin of it.
3. The user has a relationship to the project, and he is an admin.