Question

I am a newbie. I just want to create a method in the controller for the following code to avoid repeating again in the view. How can I write in a short and elegant way in ruby on rails?

<% @A = ....... %>
<% @B = ....... %>
<% @C = ....... %>
<% @D = ....... %>
<% @E = ....... %>

<% if (@A || @B || @C) %>
  <label> One: </label>
  <%= ... %>

  <label> Two: </label>
  <%= ... %>
<% end %>

<% if (@A || @B || @C || (@D && @E)) %>
  <label> Three: </label>
  <%= ... %>
<% end %>

Answer 1

assuming your model is called User and the code you provided is placed in “app/views/users/show.html.erb”

I suggest the following refactoring:
(you need to replace A,B,C,D and E with the appropriate logic and rename the methods to something more meaningful)

# in "app/helpers/users_helper.rb"
module UsersHelper
  def isABC
    return A || B || C
  end

  def isDandE
    return D && E
  end
end

# in "app/views/users/show.html.erb
<% if (isABC) %>
  <label> One: </label>
  <%= ... %>

  <label> Two: </label>
  <%= ... %>
<% end %>

<% if (isABC || isDandE) %>
  <label> Three: </label>
  <%= ... %>
<% end %>

---

You can read up on Rails helpers here: http://paulsturgess.co.uk/articles/49-using-helper-methods-in-ruby-on-rails

Basically the reponsibility of a controller is to accept incoming web requests, fetch the neccessary data (Model) and call the appropriate View for rendering.

Rails has Helpers that can be called from your Views. The idiom is that you put any advanced logic used in the view into the Helper