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PORails 3 has_many :through + join table conditions / scoping
 

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    <p>I'm working on an app that has the models <code>User</code> and <code>Project</code>, and <code>User</code> can be assigned to multiple <code>Project</code>s, via <code>ProjectUser</code>, with a role (e.g. Developer, Designer).</p> <pre><code>Project has_many :project_users has_many :users, :through =&gt; :project_users User has_many :project_users has_many :projects, :through =&gt; :project_users ProjectUser (user_id, project_id, role) belongs_to :user belongs_to :project </code></pre> <p>I can call <code>@project.users</code> and <code>@user.projects</code>, but since there are varying roles, I'd like to be a bit more specific with the relations. Ideally, I want to be able to do the following:</p> <pre><code>@project.developers # returns @project.users, but only where ProjectUser.role = 'Developer' @project.designers &lt;&lt; @user # creates a ProjectUser for @project, @user with role 'Designer' @user.development_projects # returns projects where @user is assigned as a 'Developer' @user.design_projects &lt;&lt; @project # creates a ProjectUser for @project, @user with role 'Designer' </code></pre> <p>I currently have the following code:</p> <pre><code>has_many :developers, :through =&gt; :project_users, :source =&gt; :user, :class_name =&gt; "User", :conditions =&gt; ['project_users.role = ?','Developer'] </code></pre> <p>But this only really does the fetching one-way, and doesn't give me much else - I can't build or assign or anything.</p> <p>I'm attempting some more complex logic which I think might work, but would appreciate some pointers:</p> <pre><code>has_many :developer_assignments, :source =&gt; :project_user, :conditions =&gt; { :role =&gt; 'Developer' } has_many :developers, :through =&gt; :developer_assignments # class_name? </code></pre> <p>Any suggestions? Thanks!</p>
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