title: How to define additional parameters in Dojo's JsonRestStore (dojox.data.JsonRestStore)?
body: <p>I'm working on <strong>dojox.data.JsonRestStore</strong> in conjunction with <strong>dojox.grid.DataGrid</strong> to access a REST API which has an authentication process similar to OAuth where query parameters are signed by a Shared Secret.</p>
  
  <p>For example, getting a list of books might look like this.
  GET <a href="http://testserver.com/api/book/?aaa=111&amp;bbb=222&amp;apiKey=123123&amp;apiSign=A62D34764EFF12242341" rel="nofollow">http://testserver.com/api/book/?aaa=111&amp;bbb=222&amp;apiKey=123123&amp;apiSign=A62D34764EFF12242341</a></p>
  
  <p>Please note <strong>apiSign</strong> is hash string generated from concatenated string of all parameters and their values. Meaning I must apply this logic after JsonRestStore finishes setting up its own parameters.</p>
  
  <p>How can I prepare these parameters? From what I could find, <strong>defining a custom service function</strong> seems to be one of the solutions but couldn't find good documentation on the topic. <strong>Extending JsonRestStore's _doQuery() function</strong> appears to be another solution but not sure if that's the right one.</p>
  
  <p>If someone can point me to the right direction, I would really appreciate it.</p>
  
  <p>Thanks!</p>