EF ASNotTracking导致错误。“System.DateTime”类型的表达式不能用于分配给“System.Nullable”类型的“1[System.DateTime]”

今天,我决定将我的一个旧的Web项目从ASP.NET核心1.1升级到2.1,一切进展顺利,直到我尝试从数据库中检索LocalEvent的列表。我使用了.asnotracking,因为除了排序/过滤之外,我不需要对对象进行任何更改。

这是错误:

“System.DateTime”类型的表达式不能用于赋值给 类型“system.nullable`1[system.datetime]”

这是我遇到问题的代码:

    var today = DateTime.Now;

    var events = await _context.LocalEvent.Where
    (x => x.ReoccurUntil > today || x.EventEnd > today).AsNoTracking().ToListAsync();

这是本地事件模型:

public class LocalEvent
{
    [NotMapped]
    private DateTime? dateCreated;

    [Key]
    public Guid Id { get; set; }

    [MaxLength(200)]
    [Display(Name = "Event Location")]
    [DataType(DataType.MultilineText)]
    public string Location { get; set; }

    [Display(Name = "Added By")]
    public string Author { get; set; }

    [Display(Name = "Contact")]
    public string EventContact { get; set; }

    [Display(Name = "Event Name")]
    public string EventName { get; set; }

    [DataType(DataType.MultilineText)]
    [Display(Name = "Details")]
    public string EventInfo { get; set; }

    [DataType(DataType.Currency)]
    [DisplayFormat(DataFormatString = "{0:C0}", ApplyFormatInEditMode = true)]
    [Display(Name = "Cost")]
    public Decimal? EventCost { get; set; }

    //DateStuff
    [Display(Name = "Date Created")]
    public DateTime DateCreated
    {
        get { return dateCreated ?? DateTime.Now; }
        set { dateCreated = value; }
    }

    [Display(Name = "Event Start")]
    public DateTime EventStart { get; set; }


    [DateGreaterThan("EventStart")]
    [Display(Name = "Event End")]
    public DateTime EventEnd { get; set; }

    public DateTime ReoccurUntil { get; set; }

    [Display(Name = "Reoccurrence Type")]
    public TypeOfOccurrence OccurrenceType { get; set; }

    [Display(Name = "Which Occurence of Weekday")]
    public Nth NthReOccurence { get; set; }

    [Display(Name = "Weekday for Reoccurence")]
    public DayOfWeek ReoccurrenceDay { get; set; }

    [Display(Name = "Occurrence Rate")]
    public OccurrenceRate Occurrence { get; set; }
    public bool DoesReoccur { get; set; }

    [DataType(DataType.ImageUrl)]
    public string Image { get; set; }

    public string ImageDeletePath { get; set; }
    public string Slug { get; set; }
}

现在,我只是简单地取消了跟踪,以使事情再次工作。我做错什么了吗?

这个错误真的很奇怪,因为它提到了日期,所以花了一段时间追溯到AsNotTracking,我删除了与日期有关的任何内容,最初只是删除了可以为空的日期,然后我实现了对管理列表(完整的跟踪列表)的类似调用,唯一的区别是窥探,那是我(测试后)决定在这里问的时候。

我的想法是,如果我没有修改,删除等意图,我应该避免跟踪,以提高性能!?

希望有人能对这个问题有所了解!事先谢谢!