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POHow to access the joining model on a has_many :through relationship
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  1. POHow to access the joining model on a has_many :through relationship
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    copied!<p>I have a typical many-to-many relationship using <code>has_many =&gt; :through</code>, as detailed below.</p> <pre><code>class member has_many member_roles has_many roles, :through =&gt; :member_roles end class role has_many member_roles has_man members, :through =&gt; :member_roles end class member_role belongs_to :member belongs_to :role # has following fields: member_id, role_id, scope, sport_id end </code></pre> <p>What I'm trying to do here is allow members to be assigned roles. Each member role has a scope, which by default is set to "All" but if desired can be set to "Sport". If the scope is set to sport then we also capture the sport_id, which allows us to restrict assess on that role to a particular sport (ie, can only manage the teams of that sport, rather than the teams of every sport). Sounds simple enough.</p> <p>I have setup my <code>update_member_roles</code> action something like this:</p> <pre><code>def update # Assume we passing a param like: params[:member][:roles] # as an array of hashes consisting of :role_id and if set, :sport_id roles = (params[:member] ||= {}).delete "roles" @member.roles = Role.find_all_by_id(roles.map{|r| r["role_id"]}) if @member.update_attributes params[:member] flash[:notice] = "Roles successfully updated." redirect_to member_path(@member) else render :action =&gt; "edit" end end </code></pre> <p>The above works nice enough, it sets the appropriate member_roles very nicely... but as I'm working on the Role model and not the MemberRole model I'm kind of stuck as to how I can access the joining model to set the :scope and :sport_id.</p> <p>Any pointers here would be much appreciated.</p>
 

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