is there a more elegant way to write this? variable within activerecord is not nil

Question

I ruby on rails, in view, I would like to check if there is some variable not null. I suppose first I must check if there is even a object and then check if that r1!=nil. Is there a better way? thank you

      <% neki=Anketare.where("semestar_id=? AND JMBAG=? AND sifPred=? and vrstaNastave=?",session[:semestar_id],predmett.JMBAG,params[:format],Vrstanastave.find(1).vrstaNastave) %>
  <% if neki.exists? %>
    <% if neki.first.r1!=nil %>
        A+
    <% else %>
    A-
    <% end %>       
    <% else %>
    A-
    <% end %>       

Answer 1

Using the ternary operator , I would suggest something like

Model or controller! -

@neki=Anketare.where("semestar_id=? AND JMBAG=? AND sifPred=? and vrstaNastave=?",
session[:semestar_id],predmett.JMBAG,params[:format],
Vrstanastave.find(1).vrstaNastave)

View:

<%= @neki.exists? ? (@neki.first.r1!=nil ? "A+" : "A-") : "A-" %>  

might work.

You need the @ to share the variable between the controller and the view.

Answer 2

You can use foo.nil? to test if something is nil. So you can call neki.first.r1.nil? to test if it's nil. You can also just use the item itself as a boolean test:

if neki.first.r1; do_something; else; do_something_else; end

With rails you can also use foo.blank? to check if something is not nil and is not a blank string or empty array. Rails also gives you foo.present? to check if something is not blank? (the same as !foo.blank? )

So in your case you can simply change the entire set of if statements to:

<%= (neki.present? and neki.first.r1) ? "A+" : "A-" %>

Answer 3

Ugh. Use the andand gem :

<%= @neki.andand.first.r1 ? "A+" : "A-" %>

Answer 4

I wouldn't include any of the logic in the view. Instead, you can write a model that performs the logic on neki and neki.first.r1 and figures out the grade, then call that from your view.

Example:

# Model
class Neki
  def initialize(neki)
    @neki = neki
  end
  def grade
    (neki.present? and neki.first.r1) ? "A+" : "A-"
  end
end

# Controller
@neki = Neki.new(Anketare.where(...))

# View
<%= @neki.grade %>

Hope this helps!