title: How can i add custom field in admin side spree_order in Spree eCommerce?
body: <p><strong>I want to add Custom field in <em>spree_order</em> table.</strong> </p>
  
  <p><strong>I'm using spree-3.0 stable and rails 4.2.0.</strong></p>
  
  <p>Field name is pre_order_id.</p>
  
  <p>Using Strong Params.</p>
  
  <p>Right now It gives Error in console <strong>Unpermitted parameter: pre_order_id</strong>.</p>
  
  <p>I also append <strong>pre_order_id</strong> using below steps.</p>
  
  <p><strong>This code write in spree.rb</strong></p>
  
  <pre><code>Spree::PermittedAttributes.class_eval do
  
   class_variable_set(:@@checkout_attributes,class_variable_get(:@@checkout_attributes).push(:pre_order_id))
  
  end
  </code></pre>
  
  <p>But still problem remaining.</p>
  
  <p>Thanks in Advance.</p>