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Jun: 04; 2008

delegate not in the Rails API

By: Matt Elhotiby | Tags:

Tutorial

The delegate method allows you to add contained objects methods to your current objects methods. For example suppose you have two models User and Organization….

class User < ActiveRecord::Base
  belongs_to :organization

class Organization < ActiveRecord::Base

has_many :users

Ok now lets say that you want to access the taxid for the employee but the taxid is in the organizations table, you would normally have to access it like this….

@a_user.organization.taxid

but with the delegate method you can insert

class User < ActiveRecord::Base
  belongs_to :organization

  delegate :taxid, :to => :organization

and now to can skip the middle man and do…

@a_user.taxid

which returns the same result

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4 Responses to “delegate not in the Rails API”

On June 4th, 2008 at 3:04 pm Alex S. said:

Good post, but did you mean to say “delegate NOW in the Rails API” instead of “delegate NOT in the Rails API”?

On June 4th, 2008 at 3:36 pm Matt Elhotiby said:

Thanks Alex, and yes I could have named it “delegate NOW in the Rails API” but I did that on purpose because I couldn’t find the method in the rails API so I named it that.

On June 5th, 2008 at 1:52 pm Tekin said:

One neat trick to avoid exceptions when the association isn’t compulsory is to do:

delegate :taxid, :to => ‘(organization or return nil)’

On June 5th, 2008 at 1:55 pm Matt Elhotiby said:

thanks Tekin, will have to use that one