EF Code First“无效的列名称”鉴别符“”但没有继承 [英] EF Code First "Invalid column name 'Discriminator'" but no inheritance
问题描述
如何在C＃中声明类：
public class SEntry
{
public long SEntryId {get;组; }
public long OriginatorId {get;组; }
public DateTime DatePosted {get;组; }
public string Message {get;组; }
public byte DataEntrySource {get;组; }
public string SourceLink {get;组; }
public int SourceAppId {get;组; }
public int？ LocationId {get;组; }
public long？ ActivityId {get;组; }
public short OriginatorObjectTypeId {get;组; }
}
public class EMData：DbContext
{
public DbSet< SEntry> SEntries {get;组; }
...
}
当我尝试添加一个新行对于该表，我收到错误：
System.Data.SqlClient.SqlException：无效的列名称鉴别符。
仅当您从另一个类继承C＃类时，才会出现此问题，但是SEntry不是从任何东西（如上图所示）。
除此之外，当我将鼠标悬停在SEntries属性的EMData实例上时，一旦获得了调试器上的工具提示，它显示：
base {System.Data.Entity.Infrastructure.DbQuery< EM.SEntry>} = {SELECT
[Extent1]。[Discriminator] AS [Discriminator]，
[Extent1]。[SEntryId] AS [SEntryId]，
[Extent1]。[OriginatorId] AS [OriginatorId]，
[Extent1]。[DatePosted] AS [DatePosted]，
[Extent1]。[Message] AS [Message]，
[Extent1]。[DataEntrySource] AS [DataE ...
有什么建议或想法来解决这个问题的底层？我尝试重命名表，主键和其他一些东西，但没有任何作用。
SQL表：
CREATE TABLE [dbo]。[SEntries]（
[SEntryId] [bigint] IDENTITY（1125899906842624,1）NOT NULL，
[OriginatorId] [bigint ] NOT NULL，
[DatePosted] [datetime] NOT NULL，
[Message] [nvarchar]（500）NOT NULL，
[DataEntrySource] [tinyint] NOT NULL，
[SourceLink] [nvarchar]（100）NULL，
[SourceAppId] [int] NOT NULL，
[LocationId] [int] NULL，
[ActivityId] [bigint] NULL，
[OriginatorObjectTypeId] [smallint] NOT NULL，
CONSTRAINT [PK_SEntries] PRIMARY KEY CLUSTERED
（
[SEntryId] ASC
）WITH（PAD_INDEX = OFF，STATISTICS_NORECOMPUTE = $ {$ {
ALTER TABLE [dbo]。[SEntries ] WITH CHECK ADD CONSTRAINT [FK_SEntries_ObjectTypes] FOREIGN KEY（[OriginatorObjectTypeId]）
参考文献[dbo]。[ObjectTypes]（[ObjectTypeId]）
GO
ALTER TABLE [dbo]。[SEntries] CHECK CONSTRAINT [FK_SEntries_ObjectTypes]
GO
ALTER TABLE [dbo]。[SEntries] WITH CHECK ADD CONSTRAINT [FK_SEntries_SourceApps] FOREIGN KEY（[SourceAppId]）
REFERENCES [dbo]。[SourceApps]（[SourceAppId]）
GO
ALTER TABLE [dbo]。[SEntries] CHECK CONSTRAINT [FK_SEntries_SourceApps]
GO
事实证明，实体框架将假设从映射到数据库表上的POCO类继承的任何类都需要一个Discriminator列，即使派生类不会被保存到数据库中。
解决方案非常简单，您只需将 [NotMapped] 添加为派生类的属性。
示例：
class Person
{
public string Name {get;组;
}
[NotMapped]
class PersonViewModel：Person
{
public bool UpdateProfile {get;组; }
}
现在，即使将Person类映射到Person表数据库中，不会创建Discriminator列，因为派生类具有 [NotMapped] 。
作为额外的提示，您可以使用 [NotMapped] 将您不想映射到的属性DB上的字段。
I have a table in my database called SEntries (see below the CREATE TABLE statement). It has a primary key, a couple of foreign keys and nothing special about it. I have many tables in my database similar to that one, but for some reason, this table ended up with a "Discriminator" column on the EF Proxy Class.
This is how the class is declared in C#:
public class SEntry
{
public long SEntryId { get; set; }
public long OriginatorId { get; set; }
public DateTime DatePosted { get; set; }
public string Message { get; set; }
public byte DataEntrySource { get; set; }
public string SourceLink { get; set; }
public int SourceAppId { get; set; }
public int? LocationId { get; set; }
public long? ActivityId { get; set; }
public short OriginatorObjectTypeId { get; set; }
}
public class EMData : DbContext
{
public DbSet<SEntry> SEntries { get; set; }
...
}
When I try to add a new row to that table, I get the error:
System.Data.SqlClient.SqlException: Invalid column name 'Discriminator'.
This problem only occurs if you are inheriting your C# class from another class, but SEntry is not inheriting from anything (as you can see above).
In addition to that, once I get the tool-tip on the debugger when I mouse over the EMData instance for the SEntries property, it displays:
base {System.Data.Entity.Infrastructure.DbQuery<EM.SEntry>} = {SELECT
[Extent1].[Discriminator] AS [Discriminator],
[Extent1].[SEntryId] AS [SEntryId],
[Extent1].[OriginatorId] AS [OriginatorId],
[Extent1].[DatePosted] AS [DatePosted],
[Extent1].[Message] AS [Message],
[Extent1].[DataEntrySource] AS [DataE...
Any suggestions or ideas where to get to the bottom of this issue? I tried renaming the table, the primary key and a few other things, but nothing works.
SQL-Table:
CREATE TABLE [dbo].[SEntries](
[SEntryId] [bigint] IDENTITY(1125899906842624,1) NOT NULL,
[OriginatorId] [bigint] NOT NULL,
[DatePosted] [datetime] NOT NULL,
[Message] [nvarchar](500) NOT NULL,
[DataEntrySource] [tinyint] NOT NULL,
[SourceLink] [nvarchar](100) NULL,
[SourceAppId] [int] NOT NULL,
[LocationId] [int] NULL,
[ActivityId] [bigint] NULL,
[OriginatorObjectTypeId] [smallint] NOT NULL,
CONSTRAINT [PK_SEntries] PRIMARY KEY CLUSTERED
(
[SEntryId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[SEntries] WITH CHECK ADD CONSTRAINT [FK_SEntries_ObjectTypes] FOREIGN KEY([OriginatorObjectTypeId])
REFERENCES [dbo].[ObjectTypes] ([ObjectTypeId])
GO
ALTER TABLE [dbo].[SEntries] CHECK CONSTRAINT [FK_SEntries_ObjectTypes]
GO
ALTER TABLE [dbo].[SEntries] WITH CHECK ADD CONSTRAINT [FK_SEntries_SourceApps] FOREIGN KEY([SourceAppId])
REFERENCES [dbo].[SourceApps] ([SourceAppId])
GO
ALTER TABLE [dbo].[SEntries] CHECK CONSTRAINT [FK_SEntries_SourceApps]
GO
Turns out that Entity Framework will assume that any class that inherits from a POCO class that is mapped to a table on the database requires a Discriminator column, even if the derived class will not be saved to the DB.
The solution is quite simple and you just need to add [NotMapped] as an attribute of the derived class.
Example:
class Person
{
public string Name { get; set; }
}
[NotMapped]
class PersonViewModel : Person
{
public bool UpdateProfile { get; set; }
}
Now, even if you map the Person class to the Person table on the database, a "Discriminator" column will not be created because the derived class has [NotMapped].
As an additional tip, you can use [NotMapped] to properties you don't want to map to a field on the DB.
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