title: jqgrid - postData submits previous request params and data
body: <p>I have been using <code>postData</code> to set the request params dynamically. On click of some external button, I change the grid URL and also set some additional params in <code>postData</code> like below. JqGrid seems to append all these params and it's data for all the subsequent requests. Is there a way we can control or avoid these params being sent every time?</p>
  
  <p>My grid definition:</p>
  
  <pre><code>jQuery(function() {
      $('#grid').jqGrid({
      url: 'rates.html',
      postData: {
          name: function() { return $("#name").val(); },
          rate: function() { return $("#rate").val(); },
                  .....
          }
          ....
      });
  });
  </code></pre>
  
  <p>Here in the post request: I see that <code>name</code>, <code>rate</code> params are going along with other standard jqGrid parameters like <code>sortname</code>, <code>sidx</code>, <code>rows</code>, etc...</p>
  
  <p>Now if on click of an external button, if I change the grid URL like below</p>
  
  <pre><code>$('#changeReqBtn').click(function() {
         $('#grid').setGridParam({ url: 'changeReq.html', 
                                postData: { msgIds: msgIds } });
         $('#grid').trigger("reloadGrid");     
  
  });
  </code></pre>
  
  <p>Now jqGrid sends <code>name</code>, rate, <code>msgIds</code> params </p>
  
  <p>Now if I change the URL back to rates.html say for example, on click of refresh icon, jqGrid sends the previous <code>msgIds</code> param and also the previous values. I don't want to send the previous request params in the new request when the URL changes. Is there a way we can achieve this?</p>