title: Rails - Single Table Inheritance problems. Any solutions / alternatives
body: <p>For my project management application, I am currently using Single Table Inheritance so that:</p>
  
  <p>Lead &lt; Requirement</p>
  
  <p>Project &lt; Requirement</p>
  
  <p>By which I mean to say that Lead is a Requirement and Project is a Requirement. It was okay, while I had these two only. Then I had another similar thing (Tender), so I created</p>
  
  <p>Tender &lt; Requirement</p>
  
  <p>Now the problem is when a Tender converts to a project there is no way for me to identify which projects were Tenders and which were Leads. So I can't say for example:</p>
  
  <p>Out of 100 leads I get 20 projects and out of 100 Tenders I get 5 projects. </p>
  
  <p>For now as a workaround I think I can use boolean field to say if this was a tender. But that defeats the purpose of having STI. Is there another way to do this using STI itself. Or are booleans [or some sort of category/project_type field] the only way to accomplish this. </p>
  
  <p>Can I use state_machine for this?</p>
  
  <p>I have been trying to get this right for some time now. Any help would be great.</p>