MVC 4控制器JsonResult

I have a question related to my controller in MVC. I want to loop inside my JsonResult GetAfmeldingen using foreach.

But what I do will not go inside my foreach here is my code as it looks right now

public JsonResult GetJsonAfmeldingen()
{
    if (Functions.HasLoginCookie())
    {
        if (Models.Taken.ActID > 0)
        {
            foreach (var item in Talent.Afmelding.Fetch(null, Models.Taken.ActID, null, null))
            {               
                return Json(item.Participant.CompleteName, JsonRequestBehavior.AllowGet);
            }

            return Json("Empty ?? ID = " + Models.Taken.ActID + "", JsonRequestBehavior.AllowGet);
        }
        else
        {
            return Json(null, JsonRequestBehavior.AllowGet);
        }
    }
    else
    {
        return Json(null, JsonRequestBehavior.AllowGet);
    }
}

In this example, I return a JsonResult when the first record in my list hits. I've looked to see if it works but it doesn't. The id is filled but what am I missing here? I am new to MVC.

This will terminate on the first loop of the foreach, is that what you want?

            foreach (var item in Talent.Afmelding.Fetch(null, Models.Taken.ActID, null, null))
            {

                return Json(item.Participant.CompleteName, JsonRequestBehavior.AllowGet);
            }

This is probably what doesn't work, since you cannot come into the foreach.

public JsonResult GetJsonAfmeldingen()
{
    if (Functions.HasLoginCookie())
    {
        //This one is probably not filled.
        if (Models.Taken.ActID > 0)
        {

This could be a possible solution:

public JsonResult GetJsonAfmeldingen(int actID)
{
    if (Functions.HasLoginCookie())
    {
        //Now it is filled if you post it correctly.
        if (actID > 0)
        {

After that try to test it in a smaller scope. Try to have a breakpoint on this line and see if the list is filled.

    var listAfmeldingen = Talent.Afmelding.Fetch(null, Models.Taken.ActID, null, null);
    //Breakpoint here
    int count = listAfmeldingen.Count;
    foreach (var item in listAfmeldingen)
    {   
        return Json(item.Participant.CompleteName, JsonRequestBehavior.AllowGet);
    }

Have a look at your routing as well, I use this one:

        routes.MapRoute(
            name: "Default",
            url: "{controller}/{action}/{id}",
            defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
        );