I'm really struggling to understand how to link_to a parent from with a loop.

My milestones belong_to my orders and my orders have many milestones.

In my orders index, I have a simple calendar (table_builder) which lists all my milestones.

<%= calendar_for @milestones, :year => @date.year, :month => @date.month do |t| %>
  <%#= 开发者_如何学Gocalendar_for(@orders, :year => 2009, :month => 1) do |t| %>    
    <%= t.head('Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday') %>
        <%= t.day(:day_method => :milestone_due) do |date, orders| %>
          <%= date.day %>
         <ul>
                <% for milestone in orders %>
                 <li><%= link_to milestone.name, order_path  %> </li> 
                <% end %>
         </ul>
        <% end %>
      <% end %>

This all works swimmingly well but the link doesn't work - I need it to link back to the parent order, not the milestone. It's driving me crazy now!

In my controller, I tried putting:

 @milestoneorder = Order.find(params[:id])

But that says it can't find an order without an id.

I'm obviously missing something really basic here.

You need to tell order_path which Order to link back to:

<%= link_to milestone.name, order_path(milestone.order) %>

You could probably just shorten it to this too:

<%= link_to milestone.name, milestone.order %>

UPDATE

If there's a chance some of your milestones don't have orders, you can try something like this:

<% if milestone.order %>
  <%= link_to milestone.name, order_path(milestone.order) %>
<% else %>
  <%= milestone.name %>
<% end %>

It doesn't sound like you have a route setup for order.

In the routes.rb file

resources :orders

or if you do, you aren't passing in an id for the order.

link_to "link text", order_url(:id => @order)
link_to "link text", order_url(@order) # <== shortened

lastly, the problem may be that order is nil. If it is nil, you will also get the 'can't find route' error.

UPDATE

<% orders.each do |order| %>
    <li><%= link_to milestone.name, order_path(order)  %> </li> 
<% end %>

UPDATE 2

The problem is in the names. I think that you are getting get milestones from t.day not orders.

<%= t.day(:day_method => :milestone_due) do |date, milestones| %>
    <%= date.day %>
     <ul>
            <% for milestone in milestones %>
             <li><%= link_to milestone.name, order_path(:id => milestone.order_id)  %> </li> 
            <% end %>
     </ul>
    <% end %>