复合键作为外键

您可以使用任何一种流畅的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; }}