Why can I still use access an attribute in rails console without attr_accessible?

Question

I am new to learning Rails but my current understanding of attr_accessible is that it makes an attribute of a class available outside the class scope.

However without making an attribute attr_accessible I am able to access that attribute in a helper method argument in the Rails console.

'005 > Todo.create(:todo_item => "Pay internet bill")

   (0.1ms)  begin transaction

  SQL (0.6ms)  INSERT INTO "todos" ("created_at", "todo_item", "updated_at") VALUES (?, ?, ?)  [["created_at", Sat, 18 Aug 2012 09:55:33 UTC +00:00], ["todo_item", "Pay internet bill"], ["updated_at", Sat, 18 Aug 2012 09:55:33 UTC +00:00]]

   (339.1ms)  commit transaction

 => #<Todo id: 6, todo_item: "Pay internet bill", created_at: "2012-08-18 09:55

However to do the same thing in a controller action :

def add

   Todo.create(:todo_item => params[:todo_text])

   redirect_to :action => 'index'

  end

In the model I need to specify

 attr_accessible :todo_item

Why is this attribute accessible in the Rails console but not in a controller method?

Answer 1

ActiveRecord creates attributes automatically based on the database schema. This is a system superficially similar to but independent from the attr_accessor system that's part of core Ruby.

Internally they have nothing in common. An attr_accessor is just a wrapper around a simple instance variable but inside a model instance there's a lot more going on.

You can add accessible attributes to your models for things that need to be stored temporarily but not in the database. This is a fairly uncommon thing to do, though.