我不确定为什么会有错误,如果有人能对我说清楚,那就太好了。
public List<ElementModelForCourseIndex> GetElementModelsForCourseIndex(int elementId, int userId, int depthLevel = 2)
    {
        List<ElementModelForCourseIndex> TypesName;
        ElementType type = new ElementType();
        using (var db = DataContextManager.AleStoredProcsContext)
        {
            TypesName = db.GetElementModelsForCourseIndex<ElementModelForCourseIndex>(elementId, userId, r => new ElementModelForCourseIndex{
                    Id = ElementsModelsForCourseIndexMap.Id(r),
                    Identity = ElementsModelsForCourseIndexMap.Identity(r)
                }).OrderBy(n=>n.Identity).ToList();
        }
        foreach (ElementModelForCourseIndex typeContent in TypesName)
        {
            typeContent.Children = GetElementChildrenModelsForCourseIndex(elementId, userId, type.ModelId, depthLevel);
        }
    }
    public List<ElementModelForCourseIndex> GetElementChildrenModelsForCourseIndex(int elementId, int userId, ElementType typeId, int depthLevel = 2)
    {
        using (var db = DataContextManager.AleStoredProcsContext)
        {
            return db.GetElementWithCalendarAndPermsByModel<ElementModelForCourseIndex>(elementId, userId, typeId.Id, r => new ElementModelForCourseIndex
            {
                IdentityName = ElementsModelsForCourseIndexMap.IdentityName(r),
                ValueString = ElementsModelsForCourseIndexMap.ValueString(r),
                TimeReleased = ElementsModelsForCourseIndexMap.TimeReleased(r),
                TimeDue = ElementsModelsForCourseIndexMap.TimeReleased(r)
            }).OrderBy(i => i.IdentityName).ToList();
        }
    }
错误出现在需要返回语句的这一行的顶部方法中。