ASP.NET MVC Ajax - InvalidOperationException, sequence contains no elements

Question

Whenever I make an Ajax call to a certain method, it gives an InvalidOperationException with the message "sequence contains no elements", which is obvious as I want to verify that it gives an error when entering a non-existing article.

The Ajax which calls to the method

$.ajax({
    url: '@Url.Action("GetArticleName", "Date")',
    data: JSON.stringify({ barcode: $("#ArticleBarcode").val() }),

    type: 'POST',
    contentType: 'application/json; charset=utf-8',

    dataType: 'json',
    success: function (result) {
        var divInsert = document.getElementById("ArticleName");
        divInsert.innerHTML = result;
        validArticle = true;
    },

    error: function (xhr, s, error) {
        if (xhr.status == 404) {
            var divInsert = document.getElementById("ArticleName");
            divInsert.innerHTML = "Varen blev ikke fundet";
        }
        else {
            alert("error: " + s);
        }
        validArticle = false;
    }
});

The method which returns the error

[HttpPost]
public ActionResult GetArticleName(long barcode)
{
    ArticleDbContext artdb = new ArticleDbContext();
    String article = (String)(from art in artdb.Articles where art.Barcode == barcode select art.Name).SingleOrDefault();
    if (article == null)
    {
        return HttpNotFound();
    }
    return Json(article);
}

Stacktrace

[InvalidOperationException: Sekvensen indeholder ingen elementer] 
System.Linq.Enumerable.First(IEnumerable`1 source) +269
System.Data.Objects.ELinq.ObjectQueryProvider.<GetElementFunction>b__0(IEnumerable`1 sequence) +40
System.Data.Objects.ELinq.ObjectQueryProvider.ExecuteSingle(IEnumerable`1 query, Expression queryRoot) +59
System.Data.Objects.ELinq.ObjectQueryProvider.System.Linq.IQueryProvider.Execute(Expression expression) +133
System.Data.Entity.Internal.Linq.DbQueryProvider.Execute(Expression expression) +123
System.Linq.Queryable.First(IQueryable`1 source) +251
DatoCheckerMvc.Controllers.DateController.GetArticleName(Int64 barcode) in c:\Users\frederik\Documents\Visual Studio 2012\Projects\DatoCheckerMvc\DatoCheckerMvc\Controllers\DateController.cs:66   lambda_method(Closure , ControllerBase , Object[] ) +165
System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) +14
System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) +208
System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +27
System.Web.Mvc.Async.<>c__DisplayClass42.<BeginInvokeSynchronousActionMethod>b__41() +28
System.Web.Mvc.Async.<>c__DisplayClass8`1.<BeginSynchronous>b__7(IAsyncResult _) +10
System.Web.Mvc.Async.WrappedAsyncResult`1.End() +57
System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) +48
System.Web.Mvc.Async.<>c__DisplayClass39.<BeginInvokeActionMethodWithFilters>b__33() +57
System.Web.Mvc.Async.<>c__DisplayClass4f.<InvokeActionMethodFilterAsynchronously>b__49() +223
System.Web.Mvc.Async.<>c__DisplayClass37.<BeginInvokeActionMethodWithFilters>b__36(IAsyncResult asyncResult) +10
System.Web.Mvc.Async.WrappedAsyncResult`1.End() +57
System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) +48
System.Web.Mvc.Async.<>c__DisplayClass2a.<BeginInvokeAction>b__20() +24
System.Web.Mvc.Async.<>c__DisplayClass25.<BeginInvokeAction>b__22(IAsyncResult asyncResult) +102
System.Web.Mvc.Async.WrappedAsyncResult`1.End() +57
System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +43
System.Web.Mvc.<>c__DisplayClass1d.<BeginExecuteCore>b__18(IAsyncResult asyncResult) +14
System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +23
System.Web.Mvc.Async.WrappedAsyncResult`1.End() +62
System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +57
System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +23
System.Web.Mvc.Async.WrappedAsyncResult`1.End() +62
System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +47
System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +10
System.Web.Mvc.<>c__DisplayClass8.<BeginProcessRequest>b__3(IAsyncResult asyncResult) +25
System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +23
System.Web.Mvc.Async.WrappedAsyncResult`1.End() +62
System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +47
System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9690172
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155

I have tried to insert a breakpoint at the line with the Linq query but it seems to throw it already on the method with the method name.

What is the problem?

Your using SingleOrDefault(). Have you checked that the query is not returning more than one element (SingleOrDefault() throws an InvalidOperationException if theres more than one element)? — , May 08 '14 at 08:45
Sure but there are no element and I have tried `FirstOrDefault()` too. Both threw the error. — Zinoex, May 08 '14 at 08:54

Systematix Infotech · Accepted Answer · 2014-05-08T09:13:07.340

1

Change your query to:

var article = from art in artdb.Articles where art.Barcode == barcode select art;

var firstUser = article .SingleOrDefault();

or

var firstUser = article .FirstOrDefault();

edited May 08 '14 at 09:13

answered May 08 '14 at 08:43

Systematix Infotech

2,345
1
14
31

Ehsan Sajjad · Answer 2 · 2014-05-08T09:43:20.837

0

you need to use FirstOrDefault() as more than one objects may exist.

do like this:

var result = (from art in artdb.Articles 
              where art.Barcode == barcode 
              select art).FirstOrDefault();

string Name = result.Name;

you can also do like this:

 var result = artdb.Articles.FirstOrDefault(art=>art.Barcode == barcode);

but If only one object will always be returned then use SingleOrDefault():

 var result = artdb.Articles.SingleOrDefault(art=>art.Barcode == barcode);

edited May 08 '14 at 09:43

answered May 08 '14 at 09:12

Ehsan Sajjad

61,834
16
105
160

Either one or zero element is ever returned but still this does not work. I do not understand why. – Zinoex May 08 '14 at 09:42
if will be 1 or null go with ``SingleOrDefault`` – Ehsan Sajjad May 08 '14 at 09:44
SingleOrDefault returns null if no row found else that row is returned – Ehsan Sajjad May 08 '14 at 09:56
you must be doing some other mistake otherwise this line should work for sure – Ehsan Sajjad May 08 '14 at 09:57
It throws the error on the line with `public ActionResult GetArticleName(long barcode)` and that does confuse me even more. – Zinoex May 08 '14 at 09:58
pass hardcoded barcode instead of variable and see what happens – Ehsan Sajjad May 08 '14 at 09:59
in ajax call do like this: ``data: { barcode:$("#ArticleBarcode").val() }`` – Ehsan Sajjad May 08 '14 at 10:00
It's a 500 internal server error, and there is no problem at all when it is a barcode of an article in the system so I am sure it passes the barcode correctly. – Zinoex May 08 '14 at 10:02
The ajax call with `data: {barcode: $("#ArticleBarcode").val()}` does not work. I have tried. – Zinoex May 08 '14 at 10:02
alert ArticleBarCode val to check is it null or has value – Ehsan Sajjad May 08 '14 at 10:06
It has the value I want to fetch and there is no problem with it. – Zinoex May 08 '14 at 10:26
rempve datatype json and pass like this ``data: {barcode: $("#ArticleBarcode").val()}`` – Ehsan Sajjad May 08 '14 at 10:27
It returns a 500 internal server error (invalid JSON primitive) – Zinoex May 08 '14 at 10:37
is your action called? – Ehsan Sajjad May 08 '14 at 10:40
youar action is called it means, its error coming in action – Ehsan Sajjad May 08 '14 at 10:41
The action `GetArticleName` is called when code is as written in the OP executes but not called when using `data: {barcode: $("#ArticleBarcode").val()}` – Zinoex May 08 '14 at 10:56
very strange, when you do ``data: {barcode: $("#ArticleBarcode").val()}`` make sure to remove ``datatype:json`` – Ehsan Sajjad May 08 '14 at 11:03
I had to remove contentType too. But it still returns the error mentioned in OP. – Zinoex May 08 '14 at 11:21

ASP.NET MVC Ajax - InvalidOperationException, sequence contains no elements

2 Answers2