Question

我在尝试映射现有旧数据库时遇到问题。在这个例子中，一个国家有很多城市。

问题是City表上的外键不是Country表的主键

表格定义

CREATE TABLE [dbo].[CD_Country](
 [Id] [int] IDENTITY(1,1) NOT NULL,
 [Code] [char](2) NOT NULL,
 [Name] [nvarchar](50) NOT NULL,
 CONSTRAINT [PK_CD_Country] PRIMARY KEY CLUSTERED 
(
 [Id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

CREATE TABLE [dbo].[CD_City](
 [Id] [int] IDENTITY(1,1) NOT NULL,
 [Code] [char](3) NOT NULL,
 [Name] [nvarchar](50) NOT NULL,
 [CountryCode] [char](2) NOT NULL,
 CONSTRAINT [PK_CD_City] PRIMARY KEY CLUSTERED 
(
 [Id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

我尝试做这样的事情，但我得到例外。

“导航属性'Country'到连接表'CD_Country'的映射无效。”Test_SOLEF.City“类型的每个键属性必须在映射中只包含一次。”

public static class Test
{
    public static void DoIt()
    {
        using (TestEFContext context = new TestEFContext())
        {
            foreach (Country country in context.Coutries.ToList())
            {
                Console.WriteLine(string.Format("{0} has {1} cities.", country.Name, country.Cities.Count));
            }
        }
    }
}

public class TestEFContext : DbContext
{
    public IDbSet<Country> Coutries { get; set; }
    public IDbSet<City> Cities { get; set; }

    public TestEFContext()
    {
        ObjectContext.ContextOptions.LazyLoadingEnabled = true;
    }

    protected override void OnModelCreating(System.Data.Entity.ModelConfiguration.ModelBuilder modelBuilder)
    {
        // city
        modelBuilder.Entity<City>()
            .HasKey(p => p.Id)
            .MapSingleType()
            .ToTable("CD_City");

        modelBuilder.Entity<City>()
            .Property(c => c.Id).IsIdentity();

        modelBuilder.Entity<City>()
            .HasOptional(c => c.Country)
            .WithMany(c => c.Cities)
            .Map(
                "CD_Country",
                (city, country) => new 
                {
                    CountryCode = city.CountryCode,
                    Code = country.Code
                });

        // country
        modelBuilder.Entity<Country>()
            .HasKey(p => p.Id)
            .MapSingleType()
            .ToTable("CD_Country");

    }

}

public class City
{
    public int Id {get;set;}
    public string Code {get;set;}
    public string Name {get;set;}
    public string CountryCode {get;set;}

    public virtual Country Country {get;set;}
}

public class Country
{
    public int Id {get;set;}
    public string Code {get;set;}
    public string Name {get;set;}

    public virtual ICollection<City> Cities {get;set;}
}

Answer 1

微软的官方回复

“FK到非主要密钥是实体框架目前不支持的东西，但我们正在努力。

谢谢，Arthur“

论坛帖子http://social.msdn.microsoft.com/Forums/en-US/adonetefx/thread/56eedb7b-3e2a-4a2b-bd62-d451753bd9b5/#903991f6-7c5e-4aa4-a560-ef9826f8c660

如何在实体框架4.0 Code First CTP4中映射非主键的集合？

1 个答案: