Question

I’m using a standard .each loop to list the names of authors assigned to a contract for a particular project.

This works fine, when there’s just one author:

<% @product.contracts.each do |product| %>
  <%= product.author.full_name %>
<% end %>

But more than one author and it looks really ugly. So I tried this:

<% @product.contracts.each do |p| %>
  <%= p.author.full_name %>
  <%= "," unless p == @product.last %>
<% end %>

But that didn’t work. I got: undefined method last for #<Product:0x105e7ac38>

Then, I tried this: <%= @product.map{|p| p.author.full_name}.join(",") %>

That didn’t work either. I got: undefined method map for #<Product:0x105c6d760>

I’m sure I’m doing something silly wrong, but I can’t see it.

Answer 1

You are trying to call these methods on a singular object, rather than an array of them(which support last and map).

@product is a model object rather than an array of them, which is what you are expecting.

From your code, you want:

@product.contracts.last

or

 @product.contracts.map{|contract| contract.author.full_name}.join(",")

because contracts(assuming) is an array that responds to map and last.