SubSonic'；中的NullReferenceException；s Json请求后的2.2 RecordBa

我有一个MVC项目，它使用WCF服务。该服务返回一个位置集合，用于在文本框中筛选自动完成。

最初，我用自己的"Person"对象尝试了这个方法，以确保整个过程都能正常工作。

jQuery调用：

    $(function () {
        $("#txtGeoLocation").autocomplete({
            source: function (request, response) {
                $.ajax({
                    url: "/home/FindLocations", type: "POST", dataType: "json",
                    data: { searchText: request.term, maxResults: 10 },
                    success: function (data) {
                        response($.map(data, function (item) {
                            return { label: item.FullName, value: item.FullName, id: item.PersonId }
                            // return { label: item.GeoDisplay, value: item.GeoDisplay, id: item.GeoID }
                        }))
                    }
                })
            },
            select: function (event, ui) {
                alert(ui.item ? ("You picked '" + ui.item.label + "' with an ID of " + ui.item.id)
                    : "Nothing selected, input was " + this.value);
            }
        });
    });

控制器动作：

    [HttpPost]
    public JsonResult FindNames(string searchText, int maxResults)
    {
        PersonRepository repository = new PersonRepository();
        var result = repository.FindPeople(searchText, maxResults);
        return Json(result);
    }

个人存储库：

public class PersonRepository
{

    internal List<Person> FindPeople(string searchText, int maxResults)
    {
        List<Person> names = new List<Person>();
        BuildNameList(names);

        var result = from n in names
                     where n.FullName.Contains(searchText)
                     orderby n.FullName
                     select n;
        return result.Take(maxResults).ToList(); 
    }
    private static void BuildNameList(List<Person> names)
    {
        names.Add(new Person { PersonId = 1, FullName = "Kristina H. Chung" });
        names.Add(new Person { PersonId = 2, FullName = "Paige H. Chen" });
        names.Add(new Person { PersonId = 3, FullName = "Sherri E. Melton" });

工作得很好。。。因此，我将Json调用从/home/FindNames替换为/home/FoldLocations，并取消对以下行的注释（在我的jQuery调用中注释掉item.FullName行）：

return { label: item.GeoDisplay, value: item.GeoDisplay, id: item.GeoID }

这是我的控制器操作：

    [HttpPost]
    public JsonResult FindLocations(string searchText, int maxResults)
    {
        GeoLocationRepository repository = new GeoLocationRepository();
        var result = repository.FindGeo(searchText, maxResults);
        return Json(result);    // returned a list collection of geo locations
    }

我的存储库方法：

    internal List<FeederService.GeoLocation> FindGeo(string searchText, int maxResults)
    {
        // get geolocations from the cache
        var result = from l in HttpRuntime.Cache["WebsiteGeoLocations"] as FeederService.GeoLocationCollection
                     where l.GeoDisplay.Contains(searchText)
                     orderby l.GeoDisplay
                     select l;
        return result.Take(maxResults).ToList();
    }

一切似乎都很好，直到行动结束方法：

return Json(result);    // returned a list collection of geo locations

事实上，有一个正确的集合，里面有正确数量的项目，但没有返回给我的客户。VS弹出SubSonic文件RecordBase.cs，在获取公共字符串TableName:时出现空引用异常

    /// <summary>
    /// Name of the table in the database that contains persisted data for this type
    /// </summary>
    /// <value>The name of the table.</value>
    [XmlIgnore]
    [HiddenForDataBinding(true)]
    public string TableName
    {
        get { return BaseSchema.TableName; }  // <--- error occurs here
    }

这是由于某种实体引用问题导致的吗？因为我是引用FeederService.GeoLocation对象，我该如何实现这一点？

这些实体都在DAL项目中，从我的FeederService引用并通过其公开：GeoLocationCollection〔CollectionDataContract〕

[Serializable]
[CollectionDataContract]
public partial class GeoLocationCollection : ActiveList<GeoLocation, GeoLocationCollection>
{      
    public GeoLocationCollection() {}

我在GeoLocation中添加了[DataContract]。

我还在jquery代码中放置了"debugger；"（将它移到函数中），但我无法调试返回的数据。我怎样才能做到这一点？

最后，只有当集合中存在匹配项时，才会出现问题。

    List<WebsiteGeoLocation> geoList = null;
    internal List<WebsiteGeoLocation> FindGeo(string searchText, int maxResults)
    {
        // get geolocations from the cache
        var result = from l in HttpRuntime.Cache["WebsiteGeoLocations"] as FeederService.GeoLocationCollection
                     where l.GeoDisplay.Contains(searchText)
                     orderby l.GeoDisplay
                     select l;
        geoList = new List<WebsiteGeoLocation>();
        foreach (FeederService.GeoLocation location in result)
        {
            geoList.Add(new WebsiteGeoLocation
            {
                GeoID = location.GeoID,
                GeoDisplay = location.GeoDisplay,
                GeoCity = location.GeoCity,
                GeoState = location.GeoState,
                WebsiteID = location.WebsiteID,
                WorldCitiesID = location.WorldCitiesID
            });
        }
        return geoList.Take(maxResults).ToList();
    }