MVC Json Ajax 二级 级连

<script type="text/javascript">
$(document).ready(function() {
$("#teamName").change(function() {
$.getJSON('/team/SelectProduct', { teamName: $("#teamName").val() }, function(data) {
$("#productID").empty();


$.each(data, function(i, item) {
$("<option></option>")
.val(item)
.text(item)
.appendTo($("#productID"))
});
});
})
});
controller:
public ActionResult SelectProduct()
{

string teamName = Request.Params["teamName"];
int teamID = dc.TestTeams.Where(x => x.Name == teamName).SingleOrDefault().Id;
var productCollection = dc.Products.Where(x => x.TestTeamId == teamID).Select(x=> x.ShortName);
return Json(productCollection);


}