调用MVC的目标已引发异常

Question

I have an ajax call and I need to get the list of data as JSON from my controller. I keep on getting this exception.

Given below is my ajax call:

$('#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!!!");
    }
});
});

Controller code:

I can get the parameter value from the ajax and get all values from db.

    [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);
    }

Exception Message:

Exception has been thrown by the target of an invocation.

Exception Stack trace:

   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

Based on the stack trace, it looks like the error is occurring when MVC tries to JSON-serialize the returned value. Since this value is a List<Property> , it's likely that the Property class has a member on it which throws exceptions when invoked under certain circumstances.

Consider creating a separate Data Transfer Object class to return instead of the model class you're using. Or, check the Entity model class to see why invoking its properties might throw an exception.

As a side note, if your entity model is set up correctly, you should be able to simplify your query logic quite a bit:

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

This will complete in a single database round-trip, whereas your current code makes several round trips.