asp.net mvc - Working on view with two forms on one controller in mvc 5 -

i have 1 drop down box. based on selected item of dropdownbox want generate form below on same view, please find code below.

[httpget] public actionresult binddropdown() {     viewbag.doctype = new selectlist(db.doctypemasters, "id", "doctypename");       return view(); }  [httppost] public actionresult binddropdown(string doctype) {     string doc = doctype.trim();     return view(); } 

this view code

@model c3cardkyc.models.doctypemaster  @{     viewbag.title = "binddropdown"; }   <h2>binddropdown</h2> <script src="http://code.jquery.com/jquery-1.9.1.js" type="text/javascript"></script> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script> <script type="text/javascript">      $(document).ready(function () {         $('#myidandname').change(function () {              var doctype = $("#myidandname option:selected").text();              alert(doctype);             $.ajax({                 url: '@url.action("binddropdown", "document")',                 type: 'post',                 data: { doctype: doctype },                 success: function (result) {                     alert('success')                 }              })         });     }); </script>            <fieldset>             <legend>doctypemaster</legend>         @*select document type: @html.dropdownlist("doctype", "select");*@         @html.dropdownlist("myidandname", viewbag.doctype selectlist, " -- select document type -- ")            </fieldset>         <p id="hi">         @html.actionlink("back list", "index")         </p> <div id="hi">     @using (html.beginform("binddropdown", "document", formmethod.post, new { id = "submitform" }))     {         <fieldset>              <ol>                 <li>                     @html.labelfor(model => model.doctypename)                     @html.textboxfor(model => model.doctypename, new { maxlength = 50 })                     @html.validationmessagefor(model => model.doctypename)                 </li>              </ol> <button type="submit" id="btnsave" name="command" value="save">save</button>             <button type="submit" id="btnsubmit" name="command" value="submit">submit</button>             <button type="submit" id="btncancel" name="command" value="cancel" onclick="$('#submitform').submit()">cancel (server side)</button>         </fieldset>     } </div> 

when run below error coming. there no viewdata item of type 'ienumerable' has key 'myidandname'.

and if select item frm dropdown below form should appear. please suggest