ASP MVC 代码首先使用日期时间计算列

Question

我研究了很多例子，试图弄清楚如何在通过 unitOfWork 和 Repository pattern.[=23 保存更改时自动为每个实体设置 CreatedDate 值=]

所以我有的很简单POCO:

    public class Partners:IAutoGenerateDateFields
    {

        [Key]
        public int PartnerId { get; set; }
        public string PartnerCode { get; set; }
        public string PartnerName { get; set; }
        public string CompanyName { get; set; }
        public string City { get; set; }
        public string Address { get; set; }
        public string Phone { get; set; }
        public string Fax { get; set; }
        public string TaxId { get; set; }
        public int PartnerTypeId { get; set; }
        public int PartnerStateId { get; set; }
        public int LocationId { get; set; }

        [DatabaseGenerated(DatabaseGeneratedOption.Computed)]
        public DateTime CreatedDate { get; set; }

      //  [DatabaseGenerated(DatabaseGeneratedOption.Computed)]
      //  public DateTime ModifiedDate { get;set;}
        public virtual Locations Location { get; set; }

    }

这个Class实现了IAutoGenerateDateFields接口：

    interface IAutoGenerateDateFields
    {
        DateTime CreatedDate { get; set; }
      //  DateTime ModifiedDate { get; set; }
    }

最后在我的 unitOfWork class 中，我检查 added/modified 实体是否实现了上述接口并将 CreatedDate 值设置为当前日期：

    public void Save() {
        context.ChangeTracker.DetectChanges();

        var added = context.ChangeTracker.Entries()
                            .Where(t => t.State == EntityState.Added)
                            .Select(t => t.Entity).ToArray();
        foreach (var entity in added) {
            if (entity is IAutoGenerateDateFields) {
                var track = entity as IAutoGenerateDateFields;
                track.CreatedDate = DateTime.Now;
            }

        }

        var modified = context.ChangeTracker.Entries()
                                .Where(t => t.State == EntityState.Modified)
                                .Select(t => t.Entity).ToArray();
        foreach (var entity in modified) {
            if (entity is IAutoGenerateDateFields) {
                var track = entity as IAutoGenerateDateFields;
                track.CreatedDate = DateTime.Now;
            }
        }

        context.SaveChanges();
    }

但每次我点击 savechanges 时，我都会收到一个错误，提示 CreatedDate 不能为空。因此，实体不会设置当前日期。

我在这里错过了什么？

Answer 1

删除 [DatabaseGenerated(DatabaseGeneratedOption.Computed)] 属性，因为您在代码中生成了该值。

我昨天基本上做了同样的事情，下面的代码工作正常:

        var pendingChanges = GetContext().ChangeTracker.Entries<T>().Select(e => e.Entity).ToList();

        foreach (var entity in pendingChanges)
        {
            entity.DateModified = DateTime.Now
        }

ASP MVC 代码首先使用日期时间计算列

ASP MVC Code First working with datetime computed columns

c#

asp.net

asp.net-mvc

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unit-of-work