調用MVC的目標已引發異常

Question

我有一個ajax調用，我需要從控制器以JSON格式獲取數據列表。 我一直在得到這個例外。

下面是我的ajax調用：

$('#button1').click(function (e) {
e.preventDefault();
var id= $("#textboxvalue").val();
debugger;
var url = "@Url.Action("GetList", "xyz")";
console.log(url);
$.ajax({
    url: url,
    type: "GET",
    async: false,
    data: { id: id},
    dataType: "json",
    traditional: true,
    contentType: "application/json; charset=utf-8",
    success: function (data) {
        debugger;
        for (var i in data) {       
        }
    },
    error: function (xhr, ajaxOptions, thrownError) {
        //Always goes to error function
        alert("An error has occured!!!");
    }
});
});

控制器代碼：

我可以從ajax獲取參數值，並從db獲取所有值。

    [HttpGet]
    public ActionResult GetList(string id)
    {

        var pList = new List<Property>();
        using (var db = new LiensTrackerEntities())
        {

            var recipient = db.Recipients.FirstOrDefault(x => x.id== id);
            //Need to make sure there is an Properties object
            if (recipient != null && 
recipient.RecipientPropertyCollections.Count() != 0)
            {
                List<int> properties = 
recipient.RecipientPropertyCollections.Select(p => p.Property_ID).ToList();

                foreach (var item in properties)
                {
                    Property p1 = db.Properties.FirstOrDefault(u => 
u.PropertyID == item);
                    pList.Add(p1);
                }
// I can see the values in pList on continue it goes to ERROR function in 
Ajax with 500 error
                return Json(pList, JsonRequestBehavior.AllowGet);
            }
        }
        return Json(" No spouse info in Medicaid", 
JsonRequestBehavior.AllowGet);
    }

異常消息：

調用的目標已引發異常。

異常堆棧跟蹤：

   at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] 
arguments, Signature sig, Boolean constructor)
   at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, 
Object[] parameters, Object[] arguments)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags 
invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at System.Web.SecurityUtils.MethodInfoInvoke(MethodInfo method, Object target, Object[] args)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeCustomObject(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValueInternal(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat, MemberInfo currentMember)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValue(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat, MemberInfo currentMember)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeEnumerable(IEnumerable enumerable, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValueInternal(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat, MemberInfo currentMember)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValue(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat, MemberInfo currentMember)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeCustomObject(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValueInternal(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat, MemberInfo currentMember)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValue(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat, MemberInfo currentMember)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeEnumerable(IEnumerable enumerable, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValueInternal(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat, MemberInfo currentMember)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValue(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat, MemberInfo currentMember)
   at System.Web.Script.Serialization.JavaScriptSerializer.Serialize(Object obj, StringBuilder output, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.Serialize(Object obj, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.Serialize(Object obj)
   at System.Web.Mvc.JsonResult.ExecuteResult(ControllerContext context)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult)
   at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass21.<>c__DisplayClass2b.<BeginInvokeAction>b__1c()
   at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass21.<BeginInvokeAction>b__1e(IAsyncResult asyncResult)

Answer 1

基於堆棧跟蹤，當MVC嘗試對返回的值進行JSON序列化時，似乎發生了錯誤。 由於此值為List<Property> ，因此Property類上可能有一個成員，該成員在某些情況下被調用時會引發異常。

考慮創建單獨的數據傳輸對象類以返回而不是使用的模型類。 或者，檢查Entity模型類以查看為什么調用其屬性可能會引發異常。

附帶說明一下，如果您的實體模型設置正確，那么您應該能夠大大簡化查詢邏輯：

    using (var db = new LiensTrackerEntities())
    {
        var pList = db.Properties
            .Where(p => p.RecipientPropertiesCollection
                .Any(rp => rp.RecipientId == id))
            .ToList();
        return Json(pList, JsonRequestBehavior.AllowGet);
    }

這將在一次數據庫往返中完成，而您當前的代碼將進行幾次往返。