Forum: Ruby on Rails MTM relationship with relationship attributes

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vishu.raj (Guest)
on 2007-03-05 19:00
(Received via mailing list)
I have following many to many relationship:
class Service < ActiveRecord::Base
has_many :service_dependencies
has_many :dependents, :through => :service_dependencies

class ServiceDependency < ActiveRecord::Base
belongs_to :service
belongs_to :dependent, :class_name => 'Service', :foreign_key =>

However, in my schema the MTM table service_dependencies has few
relationship attributes as well, e.g. impact, severity, etc. along
with the foreign keys.

Right now, I'm displaying the dependent services' fields in following
<%=h dependents.send("service_name") %>

<% for dependents in @service.dependents %>
     <b>Service Name:</b><br> <%=h dependents.send("service_name")
<% end %>

I also want to display the relationship attributes, could someone
please help me by letting me know how to access them in my view page?
Vishwaraj (Guest)
on 2007-03-06 14:32

I found out the solution myself by refering to several examples and
forums. It is as easy as this:

<% for dependent in @service.dependents %>
      <b>Service Name:</b><br> <%=h dependent.send("service_name")
      <% dependency = @service.service_dependencies.find(:first,
:conditions =>
            ["dependent_service_id = ?",])%>
      <b>Impact:</b><br> <%=h dependency.send("impact") %><br>


This may be helpful for some other beginner like me.

Thanks and Regards,
Mark Reginald J. (Guest)
on 2007-03-06 15:16
(Received via mailing list)
Vishwaraj wrote:
>             ["dependent_service_id = ?",])%>
>       <b>Impact:</b><br> <%=h dependency.send("impact") %><br>
> <%end%>
> This may be helpful for some other beginner like me.

Better would be

<% sds = @service.service_dependents.find(:all, :include => :dependent)
    for service_dependent in sds %>
<b>Service Name:</b><br>
<%= h service_dependent.dependent.service_name %><br>
<%= h service_dependent.impact %><br>

We develop, watch us RoR, in numbers too big to ignore.
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