How do I add commas to the display of collection items if a collection has multiple products intelligently?

Question

Say I have a collection of objects in product.categories .

What I would like to happen is for my list of categories to be printed out like:

Men, Women

If I do:

<% product.categories.each do |cat| %>
  <% if product.categories.count > 1 %>
    <%= "#{cat.name}, " %>
  <% else %>
    <%= "#{cat.name} " %>
  <% end %>
<% end %>

That prints Men, Women, .

So without adding a billion rules to check for last element and all this stuff, how do I handle the following cases:

1. If there is one object, put no ,
2. If this is the last of multiple objects, don't put a , at the end.
3. If this is the last object, in a collection of many, end with a . <-- This is a nice-to-have but not a must have.

How do I handle this?

Thanks.

Answer 1

<%= product.categories.map{|cat| cat.name}.join(', ').to_s + "." %>

Try above, that will work. Do let me know if you want any else.

Answer 2

You can do:

<%= product.categories.collect{|c| c.name} * ', ' %>.

The "asterisk" method ( Array#* ) is an alias for Array#join .
Note the period just outside the ERb tag.