title: Ruby on rails. Controller params pre-processing
body: <p>I have a controller in ruby on rails 4 and i need to pre-process its params during request processing.</p>
  
  <p>I receive parameters:</p>
  
  <pre><code>{"_json"=&gt;[{"date"=&gt;"9/15/2014", "name"="James"},{"date"=&gt;"2/11/2014","name"=&gt;"John"}]}
  </code></pre>
  
  <p>And i need to iterate through all json array elements and update name parameter by adding 'User' post fix. So, finally my json should be:</p>
  
  <pre><code>[{"date"=&gt;"9/15/2014", "name"="James **User**"},{"date"=&gt;"2/11/2014","name"=&gt;"John **User**"}]
  </code></pre>
  
  <p>How can i do it in my controller?</p>