Rails not creating object correctly

I'm new to Ruby on Rails and I can't understand why the following simple command is not working.

2.2.1 :031 > Category.new(:name => 'Example')
 => #<Category id: nil, name: nil, created_at: nil, updated_at: nil> 

I define :name as 'Example' but the object created has name set to nil. What I am trying to do is to create a new object and then persist it to the database from Category model .

It is probably simple but does not make sense to a beginner !

Thanks