Displaying Nested Objects

rubyonrails-talk
#1

Hi,

I've got a question regarding my models in my Rails app. Let's say I
have an object:

User

which has_many:

Thing1

and Thing1 has_many:

Thing2

and Thing2 has_one:

Thing3

When I go to display this in my template, like this:

<table border="1">
  <tr>
    <th>Title</th>
    <th>Date</th>
    <th>Event</th>
  </tr>

<% @user.thing1.each do |c| %>
  <tr>
        <td><%=h c.title %></td>
  <td><%=h c.date %></td>
  <td>
    <table>
      <tr>
        <th>Thing2</th>
      </tr>
    <% c.thing2.each do |be| %>
      <tr>
        <td>
                                       <%=h be.workout_type %></td>
               <%=h be.thing3.name %>
                                </td>
      </tr>
    <% end %>
    </table>
  </td>
  </tr>
<% end %>

I get:

undefined method `name' for nil:NilClass

I'm assuming this means there is no Thing3 object for this particular
Thing2 object.

I just bought Agile Development with Rails and am starting to go
through that...it's surely noob question but can someone set me
straight?

Thanks!

Jon

#2

you're quite correct - there's no "thing3" linked to a given "thing 2".
If there *supposed* to be an associated object there, then something's
gone wrong when you've created your objects, but if it's a case that
there may or may not be a Thing3, then a simple "guard" would suffice.

<%=h be.thing3.name if be.thing3 %>

#3

Perfect...thanks!