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PORuby complex query elegant solution
 

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    <p>in my rails 4 project, I have the following tables <img src="https://i.stack.imgur.com/kiIN9.png" alt="enter image description here"></p> <p>In this <a href="https://stackoverflow.com/questions/19248761/join-query-by-date-and-primary">SO question</a>, I searched for a SQL query to fetch the <em>projects</em> with the actual <em>project status id</em> = XX. By actual, I mean the one with the max(created_at).</p> <p>I got an answer for my query which is</p> <pre><code>select p.* from projects p left join projects_status_projects psp on (psp.project_id = p.id) where created_at = (select max(created_at) from projects_status_projects where project_id = p.id) and project_status_id = XX </code></pre> <p>My models are defined</p> <pre><code>class Project &lt; ActiveRecord::Base has_many :projects_status_projects has_many :projects_statuses, :through =&gt; :projects_status_projects end class ProjectStatus &lt; ActiveRecord::Base has_many :projects_status_projects has_many :projects, :through =&gt; :projects_status_projects end class ProjectsStatusType &lt; ActiveRecord::Base belongs_to :project belongs_to :project_status end </code></pre> <p>In my <em>Project</em> model, I have the following method</p> <pre><code>def self.with_status(status) joins(:projects_status_projects) .where('projects_status_projects.created_at = (select max(created_at) from projects_status_projects where project_id = p.id)') .where('projects_status_projects.project_status_id = ?', status) end </code></pre> <p>While the query is correct, the received results are well filtered, I find this solution terrible and not elegant at all.</p> <p>Is there any way to get the same result with scopes ?</p> <p>Thanks for your help.</p>
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