c# - Entity Framework 代码首先添加额外列

Question

我已经离开 C# 和开发一段时间了，所以请耐心等待。

有一个实体类List如下:

public class List : EntityData
{
    public int ListId { get; set; }
    public string Name { get; set; }
    public string UserId { get; set; }

    public virtual List<ListItem> ListItems { get; set; }
}

但是创建的相应表使用此 DDL 以及额外的列。为什么？

CREATE TABLE [dbo].[Lists] 
(
    [Id]        NVARCHAR (128)     DEFAULT (newid()) NOT NULL,
    [ListId]    INT                NOT NULL,
    [Name]      NVARCHAR (MAX)     NULL,
    [UserId]    NVARCHAR (MAX)     NULL,
    [Version]   ROWVERSION         NOT NULL,
    [CreatedAt] DATETIMEOFFSET (7) DEFAULT (sysutcdatetime()) NOT NULL,
    [UpdatedAt] DATETIMEOFFSET (7) NULL,
    [Deleted]   BIT                NOT NULL,

    CONSTRAINT [PK_dbo.Lists] PRIMARY KEY NONCLUSTERED ([Id] ASC)
); 

Answer 1

它们不是额外的，而是由 Microsoft.Azure.Mobile.Server.EntityData 定义的。

这些额外的字段的目的是

An abstract implementation of the ITableData interface indicating how the system properties for a given table data model are to be serialized when communicating with clients when using Entity Framework for accessing the backend store. The uniform serialization of system properties ensures that the clients can process the system properties uniformly across platforms. Concrete entity framework models can derive from this base class in order to support the system properties.