Simple variable scope in Ruby

Question

I'm trying to get the following code to work, but it's giving me an undefined variable error:

class PagesController < ApplicationController
  @company = "Acme"
  def home
    @title = "Welcome to #{company}"
  end
  def faq
    @title = "FAQ | #{company}"
  end
end

How do I access @company within functions?

aef · Accepted Answer · 2011-11-22 04:47:05Z

3

As in Ruby, every class is an object too, what you are doing here is setting an instance variable named @company on the class object PagesController, not on an instance of PagesController.

What you may want is to use a constant instead of the instance variable. Maybe like this:

class PagesController < ApplicationController
  COMPANY = "Acme"

  def home
    @title = "Welcome to #{COMPANY}"
  end

  def faq
    @title = "FAQ | #{COMPANY}"
  end
end

If you want the company to change dependent of what "page" you are displaying, you should consider adding a Page model which has an attribute which holds the company name or an association to another model named Company.

answered Nov 22, 2011 at 4:47

aef

4,7587 gold badges30 silver badges46 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

maček · Accepted Answer · 2011-11-22 04:53:21Z

0

You can access it directly like this

class PagesController < ApplicationController
  @@company = "Acme"  # class var
  def home
    @title = "Welcome to #{@@company}"
  end
  def faq
    @title = "FAQ | #{@@company}"
  end
end

Or define a custom getter method like this

class PagesController < ApplicationController
  @@company = "Acme"
  def home
    @title = "Welcome to #{company}"
  end
  def faq
    @title = "FAQ | #{company}"
  end
  private
  def company
    @@company
  end
end

Or get Company name from database

class PagesController < ApplicationController
  def home
    @title = "Welcome to #{company}"
  end
  def faq
    @title = "FAQ | #{company}"
  end

  private
  def company
    @company ||= current_user.company  # get company of logged in user (and "cache" it)
    @company.name
  end
end

edited Nov 22, 2011 at 4:53

answered Nov 22, 2011 at 4:44

maček

78k37 gold badges172 silver badges200 bronze badges

4 Comments

methodofaction Over a year ago

The first example outputs nothing in #(@company), is the second one a good practice?

maček Over a year ago

I think accessing the class variable with a getter is better practice than direct access.

maček Over a year ago

I provided a more dynamic example that retrieves the company name from the current logged in user

methodofaction Over a year ago

Thanks macek, the dynamic example is great, but for my needs a simple constant might be better.

Collectives™ on Stack Overflow

Simple variable scope in Ruby

2 Answers 2

Comments

4 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

4 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related