From: Luca Pireddu <ilveroluca@...>
Date: 2005-02-19T01:44:47+09:00
Subject: Re: rails: many to many  agony

Graham Arrowsmith wrote:

> I have two classes: Projects and Company. There are many to many
> relationships between companies and project and are joined by table
> company_projects
> 
> Thing is when I render out a select list I want to make the related
> dropdown items selected :
> 
> <select name="project[company_id]">
>    <% @companies.each do |company| %>
>        <option value="<%= company.id %>" >
>          <%= ' selected' if company.id == @project.companies.id %>
>          <%=company.companyName %>
>        </option>
>    <% end %>
> </select>
> 
> However I can't seem to be able to get the project.companies.id (ie
> company_project.company_id) for the related project.
> 
> I know this is pretty darn simple but I can't seem to crack it.
> 
> Any help would be appreciated!
> 
> Graham

I've just begun using activerecord, so take my suggestion with a grain of
salt :)

project.companies should return an array of companies, no?  That makes it
wrong to say project.companies.id.  I think you want something like 

<%= ' selected' if @project.companies.member?(company) %>

Array#member? uses == to test for equality, and I think I remember reading
that AR overrides == to test for the equality of the "id" field so the
comparison should work.

Hope that helps.

Luca