请教个JSON异步获取的问题
后台代码

[HttpPost]
public JsonResult GetShipId()
{
var ship = db.chartered_ship_base_info.ToList();
StringBuilder sb = new StringBuilder();
sb.Append("<option value=\"-1\">select....</option>");
foreach (var item in ship)
{
sb.AppendFormat("<option value=\"{0}\">{1}</option>", item.chartered_ship_number, item.chartered_ship_number);
}
string result = sb.ToString();
return this.Json(result, JsonRequestBehavior.AllowGet);
}

[HttpPost]
public JsonResult GetCabinId(string shipnumber)
{

var cabin = db.ship_cabin_info.Where(c => c.chartered_ship_number == shipnumber).ToList();
StringBuilder sb = new StringBuilder();
sb.Append("<option value=\"-1\">select.....</option>");
foreach (var item in cabin)
{
sb.AppendFormat("<option value=\"{0}\">{1}</option>", item.cabin_number, item.cabin_number);
}
string result = sb.ToString();
return this.Json(result, JsonRequestBehavior.AllowGet);
}




前台代码
<script type="text/javascript">

$(function () {
$.ajax({
url: "/TestJosn/GetShipId",
type: "POST",
contentType: "application/json; charset=utf-8",
data: "{}",
dataType: "json",
success: function (data) {
$("#ShipId").empty();

$("#ShipId").html(data);
},
error: function ErrorCallback(XMLHttpRequest, textStatus, errorThrown) {
alert(errorThrown + ":" + textStatus);
}
});
// Get the departments depend on the school
$("#ShipId").change(function () {
GetCabinIdFromId($("#ShipId").val());
});
});

function GetCabinIdFromId(sId) {
$.ajax({
url: "/TestJosn/GetCabinId",
type: "POST",
contentType: "application/json; charset=utf-8",
data: "{ShipId:" + sId + "}",
dataType: "json",
success: function (data) {
$('#CabinId').empty();
$('#CabinId').html(data);
},
error: function ErrorCallback(XMLHttpRequest, textStatus, errorThrown) {
alert(errorThrown + ":" + textStatus);
}
});
}


</script>
<h2>
Index</h2>
<select id="ShipId">
<option value="-1">select....</option>
</select>
<select id="CabinId">
<option value="-1">select....</option>
</select>


问题是，GetCabinId（string shipnumber）这里总是获取不到shipnumber 的值，shipnunber总是null 是为什么呢？应该怎么改？谢谢

[解决办法]
http://stackoverflow.com/questions/13625785/asp-net-webapi-throw-404-if-method-parameter-is-string-or-int/13628252#13628252
[解决办法]
data: {"ShipId": sId},
data这里这样写