title: Rails URL billing system redirection with params for invoice creation
body: <p>I'm currently refining the flow for a payment system on a Rails app.</p>
  
  <p>First, they'll see SaaS like pricing tables with the option to choose and buy.</p>
  
  <p>Once they press "Buy Now" for their preferred plan (they're 2 payment resource types: prepaid and postpaid), if a user hasn't filled in their billing address, they will be redirected to fill it in on a separate view(if completed prior, they're directed straight to their invoice view). Upon completion, they will be redirected back to re-pick their pricing plan. </p>
  
  <p>However, for a seamless flow, i'd like to direct straight to invoice creation right after completing the billing address.</p>
  
  <p>What i thought of so far is to store the pricing plan order <code>params</code> (which includes the pricing plan id, promo code string, and payment type path) in the session before redirection for later use. I'm wondering how I can use these session params to initiate creation of the invoice and direct them back to it's view, perhaps with the <code>request.referrer</code> method?</p>
  
  <p>Thanks for the help.</p>