Question

What would you recommend as the best way to refactor these two bits of view code?

<%if Supplydetail.find_all_by_isbn_id(@isbn).first.nil? %>
<%else%>
<%if Productavailability.find_by_code(Supplydetail.find_all_by_isbn_id(@isbn).first.productsupply_supplydetail_productavailability).nil? %>
<%else%>
<li><%= Productavailability.find_by_code(Supplydetail.find_all_by_isbn_id(@isbn).first.productsupply_supplydetail_productavailability).value %></li>
<%end%>
<%end%>

and (using formtastic)

%li.tip 
  = tooltip(:test, :hover)
= f.input :relatedmaterial_relatedproduct_idvalue, :label => "Related ISBN", :as => :select, :collection => Isbn.all, :label_method => :descriptivedetail_titledetail_titleelement_titlewithoutprefix, :value_method => :productidentifier_idvalue  
%li.list
  = link_to "Edit list", isbns_path 

I have examples of each of these about a bazillion times in my app, and would like to know I’m refactoring in the best way before I dive in to this rather huge job.

Answer 1

First of all, an empty if branch in an if/else usually (but not always!) smells bad so don’t do that, it just makes your code harder to read and understand.

Also, you’re computing Supplydetail.find_all_by_isbn_id(@isbn) and Productavailability.find_by_code(...) twice just to get your <li> output. Don’t do that either.

And you might want to push most of that logic into your controller (or maybe a helper depending on where and how often it is used) to cut down on the ERB-noise.

Maybe something like this would serve you (and whoever gets to maintain your code) better; a bit of controller stuff first:

@avail  = nil
by_isbn = Supplydetail.find_all_by_isbn_id(@isbn).first
if by_isbn
    @avail = Productavailability.find_by_code(by_isbn.productsupply_supplydetail_productavailability)
end

And then in your ERB:

<% if @avail %>
    <li><%= @avail.value %></li> 
<% end %>

If you’re doing a lot of this sort of thing then you could add a Productavailability.for_isbn convenience class method in your model. Then your controller would just need:

@avail = Productavailability.for_isbn(@isbn)

But I wouldn’t worry about it until you start repeating yourself.

I’m not familiar with formtastic so I can’t help you with that.