复合键作为外键

我在MVC 3应用程序中使用entity framework4.1。 我有一个实体，我有主键由两列（复合键）组成。 这被另一个实体用作外键。 如何build立关系？ 在正常的scnerios我们使用：

public class Category { public string CategoryId { get; set; } public string Name { get; set; } public virtual ICollection<Product> Products { get; set; } } public class Product { public int ProductId { get; set; } public string Name { get; set; } public string CategoryId { get; set; } public virtual Category Category { get; set; } } 

但如果类别有两列键呢？

Answer 1

你可以使用stream利的API：

 public class Category { public int CategoryId1 { get; set; } public int CategoryId2 { get; set; } public string Name { get; set; } public virtual ICollection<Product> Products { get; set; } } public class Product { public int ProductId { get; set; } public string Name { get; set; } public int CategoryId1 { get; set; } public int CategoryId2 { get; set; } public virtual Category Category { get; set; } } public class Context : DbContext { public DbSet<Category> Categories { get; set; } public DbSet<Product> Products { get; set; } protected override void OnModelCreating(DbModelBuilder modelBuilder) { base.OnModelCreating(modelBuilder); modelBuilder.Entity<Category>() .HasKey(c => new {c.CategoryId1, c.CategoryId2}); modelBuilder.Entity<Product>() .HasRequired(p => p.Category) .WithMany(c => c.Products) .HasForeignKey(p => new {p.CategoryId1, p.CategoryId2}); } } 

或数据注释：

 public class Category { [Key, Column(Order = 0)] public int CategoryId2 { get; set; } [Key, Column(Order = 1)] public int CategoryId3 { get; set; } public string Name { get; set; } public virtual ICollection<Product> Products { get; set; } } public class Product { [Key] public int ProductId { get; set; } public string Name { get; set; } [ForeignKey("Category"), Column(Order = 0)] public int CategoryId2 { get; set; } [ForeignKey("Category"), Column(Order = 1)] public int CategoryId3 { get; set; } public virtual Category Category { get; set; } } 

Answer 2

我相信最简单的方法是在导航属性上使用数据注释，如下所示： [ForeignKey("CategoryId1, CategoryId2")]

 public class Category { [Key, Column(Order = 0)] public int CategoryId1 { get; set; } [Key, Column(Order = 1)] public int CategoryId2 { get; set; } public string Name { get; set; } public virtual ICollection<Product> Products { get; set; } } public class Product { [Key] public int ProductId { get; set; } public string Name { get; set; } public int CategoryId1 { get; set; } public int CategoryId2 { get; set; } [ForeignKey("CategoryId1, CategoryId2")] public virtual Category Category { get; set; } }