如何将身份添加到现有项目

Question

我有一个项目。 我想为它添加标识。 但是会发生错误。 我将尝试通过示例来描述我创建没有身份的新项目。 创建新的 class “用户”。

public class User
{
    public int Id { get; set; }
    public string Surname { get; set; }
}

创建上下文

 public class UserContext : DbContext
{
    public UserContext() : base("DefaultConnection")
    { }
}

更新数据库并添加 3 个项目。

接下来我要添加身份。

PM> Install-Package Microsoft.AspNet.Identity.Owin 
PM> Install-Package Microsoft.AspNet.Identity.EntityFramework
PM> Install-Package Microsoft.Owin.Host.SystemWeb 

更新 class

public class User : IdentityUser
{
    public string Surname { get; set; }
}

更新上下文

public class UserContext: IdentityDbContext<User>
{
    public UserContext() : base("DefaultConnection")
    { }
}

下一步：添加迁移

Error: 
Identity column 'Id' must be of data type int, bigint, smallint, tinyint, 
or decimal or numeric with a scale of 0, unencrypted, 
and constrained to be nonnullable.

我更新迁移文件

//AlterColumn("dbo.AspNetUsers", "Id", c => c.Int(nullable: false, identity: true));
DropColumn("dbo.AspNetUsers", "Id");
AddColumn("dbo.AspNetUsers", "Id", c => c.String(nullable: false, maxLength: 128));

下一个：更新数据库

Error: 
The CREATE UNIQUE INDEX statement terminated because a duplicate key 
was found for the object name 'dbo.AspNetUsers' 
and the index name 'PK_dbo.AspNetUsers'. 
The duplicate key value is ().

如何解决问题？

Answer 1

我想出了一个解决方案。 什么时候

DropColumn("dbo.AspNetUsers", "Id");

值更改为 NULL。 所以迁移更新

//AlterColumn("dbo.AspNetUsers", "Id", c => c.String(nullable: false, maxLength: 128));
AddColumn("dbo.AspNetUsers", "TmpId", c => c.String(nullable: false, maxLength: 128));
Sql("UPDATE dbo.AspNetUsers SET TmpId = Id");
DropColumn("dbo.AspNetUsers", "Id");
AddColumn("dbo.AspNetUsers", "Id", c => c.String(nullable: false, maxLength: 128));
Sql("UPDATE dbo.AspNetUsers SET Id = TmpId");
Sql("UPDATE dbo.AspNetUsers SET UserNAme = TmpId");
DropColumn("dbo.AspNetUsers", "TmpId");