Entity Framework - 1 to 1 relationship where one end is not a primary key

问题

I'd like to define a relationship in an Entity Framework data model that is 1-to-1 with one end as a primary key of one table and the other end a foreign key on another. For instance:

table: aspnet_Users
w/ col: UserId guid Primary Key

with the UserId property of the aspnet_Users table related to the AspUserId column of the User table:

table: User
w /col: UserId int Primary Key
w /col: AspUserId guid

When I try to do this I get an error saying that since the AspUserId field is not a primary key of it's table that won't work:

Error 21 Error 113: Multiplicity is not valid in Role 'User' in relationship 'FK_User_aspnet_Users'. Because the Dependent Role properties are not the key properties, the upper bound of the multiplicity of the Dependent Role must be *.

回答1:

Foreign keys need to map to primary keys. Otherwise, the below records could happen:

aspnet_Users
UserId 
11111111
11111111
22222222

User
UserId AspUserId
1      11111111
2      11111111

And that doesn't make sense - and breaks your 1-1 cardinality.

However - that being said (looking at an old membership db - yuck), UserId field on dbo.aspnet_Users is a primary key.

Are you sure you have your foreign key on the correct table? Does dbo.aspnet_Users on your database have the PK for UserId.

Also - try not to map the membership tables - it will be a world of pain. The relationships in the membership schema are highly complicated.

Just map your own User table. It's fine to have the FK for database-side work (auditing, stored procedures, triggers, etc).

But from the model side - you should be interacting with your User entity via EF, and your aspnet_Users (Membership) entity via the Membership Provider API.

If you need to "stitch them together" in your code (often the case), then encapsulate that behind a service.

回答2:

In response to a poster the User table:

CREATE TABLE [dbo].[User](
    [UserId] [int] IDENTITY(1,1) NOT NULL,
    [AspUserId] [uniqueidentifier] NOT NULL,
    [ModifiedDate] [datetime] NOT NULL,
    [CreatedDate] [datetime] NOT NULL,
CONSTRAINT [PK_User] PRIMARY KEY CLUSTERED 
(
    [UserId] 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].[User]  WITH CHECK ADD  CONSTRAINT [FK_User_aspnet_Users] FOREIGN     KEY([AspUserId])
REFERENCES [dbo].[aspnet_Users] ([UserId])
GO

ALTER TABLE [dbo].[User] CHECK CONSTRAINT [FK_User_aspnet_Users]
GO

来源：https://stackoverflow.com/questions/4485350/entity-framework-1-to-1-relationship-where-one-end-is-not-a-primary-key

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.net

linq

entity-framework

entity-framework-4