using variable as method in ruby

Question

what i am trying to achieve is relatively simple. I have different scopes for each page type in a page model. So in my controller I do this,

  def employer
    @body_class = "employer membership"
    is_page_present?(:employer_pages) #this checks to see if a page has user generated content for the controller action
  end 

private 

  def set_panel_sections(page)
    @page_data = CorporatePage.page.last
    @section_one = @page_data.corporate_panels.section_one
    @section_two = @page_data.corporate_panels.section_two
  end

  def is_page_present?(page_type)
    if CorporatePage.("#{page_type}").any?
      raise
      set_panel_sections(page_type)
    else
      @section_one = nil
    end
  end

I have tried different variations, including without concatenation, but all to no avail.

I get the error

undefined method `call' for #<Class:0x007f833b40b8f0>

and without the concatenation i get undefined method page_type

But in my rails console I can do this..

2.1.2 :001 > CorporatePage.employer_page.any?
   (19.2ms)  SELECT COUNT(*) FROM `corporate_pages`  WHERE `corporate_pages`.`static_descriptor` = 'employer'
 => true 
2.1.2 :002 > CorporatePage.employee_page.any?
   (0.5ms)  SELECT COUNT(*) FROM `corporate_pages`  WHERE `corporate_pages`.`static_descriptor` = 'employee'
 => false

So, for a more insightful answer I want to know, a method call isnt a string or a symbol, what is it?

How do I fix this current issue?

Thanks

FWIW, the reason you get the error you do is because `obj.()` is shorthand for `obj.call`. — Andrew Marshall, Aug 10 '14 at 23:36

score 1 · Accepted Answer · answered Aug 10 '14 at 23:25

1

What you want here is send:

  def is_page_present?(page_type)
    if CorporatePage.send(page_type).any?         
      set_panel_sections(page_type)
    else
      @section_one = nil
    end
  end

send will call the method defined at page_type at the class instance.

answered Aug 10 '14 at 23:25

Maurício Linhares

39,901
14
121
158

Use `public_send` instead of `send` whenever possible to avoid bypassing method visibility. – Andrew Marshall Aug 10 '14 at 23:36

score 0 · Answer 2 · answered Aug 10 '14 at 23:30

0

You need to use the send method. You can find a basic explanation of it here: http://ruby-doc.org/core-2.1.2/Object.html#method-i-send.

In you situation, you would change if CorporatePage.("#{page_type}").any? to if CorporatePage.send(page_type).any? and that should get you what you are after.

answered Aug 10 '14 at 23:30

dhouty

1,969
12
21

1

Use `public_send` instead of `send` whenever possible to avoid bypassing method visibility. – Andrew Marshall Aug 10 '14 at 23:38
Thanks for sharing, I wasn't aware of that until now. I will make sure to utilize that from now on. – dhouty Aug 10 '14 at 23:52

using variable as method in ruby

2 Answers2