Rails - Feb 2007 - Writing a simple accessor ... or so I thought

Hello Rubyists.

What I want is a "write once, then readonly" attribute in a subclass
of
ActiveController::Base. With "write once" in this case I mean that it
must not be changed once the object has been stored to the database.

The simplified class looks as follows:

class User < ActiveRecord::Base
  attr_reader :login

  def login=(new_login)
    @login = new_login unless !new_record?
  end
end

When I tested the method, I noticed that it behaved oddly:

An instance of User is created from the fixtures. Its login attribute is
set properly (checked it with Object::inspect). However, thatobj.login
returns nil. I thought it should be covered with the "attr_reader
:login"  statement in the User class.

What am I missing here? Thanks in advance.

-carp

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> in a subclass of ActiveController::Base. 
... must of course be "ActiveRecord::Base"

:-p

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> class User < ActiveRecord::Base
>   attr_reader :login
>
>   def login=(new_login)
>     @login = new_login unless !new_record?
>   end
> end
>
Try this:
def login=(new_login)
  write_attribute( :login, new_login ) if new_record?
end

For more info take a look at the "Overwriting default accessors"
section of the ActiveRecord::Base documentation.
http://api.rubyonrails.com/classes/ActiveRecord/Base.html

Aaron


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Aaron wrote:
> For more info take a look at the "Overwriting default accessors"
> section of the ActiveRecord::Base documentation.
> http://api.rubyonrails.com/classes/ActiveRecord/Base.html
I was able to fix it. I''ve been searching the forever, but never got to
the section you pointed out. Thanks a lot Aaron!

-carp

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