设计EF Core三个实体连接到一个表

Question

新的代码优先方法和EF Core。遇到了如何为通过共同实体加入的3个实体实施解决方案的问题。

这是我的实体

 public class Activity
    {
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        [Key]
        public int Id { get; set; }
        public string Name { get; set; }     
        public ICollection<RoleApplicationActivity> RoleActivities{ get; set; 
    }



 public class Application
    {
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        [Key]
        public int Id { get; set; }
        public string Name { get; set; }
        public ICollection<RoleApplicationActivity> RoleActivities { get; set; }
    }

public class Role
    {
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        [Key]
        public int Id { get; set; }
        public string Name { get; set; }
        public string Description { get; set; }

        public ICollection<RoleApplicationActivity> ApplicationActivities { get; set; }
    }

 public class RoleApplicationActivity
    {

        public int RoleId { get; set; }
        public Role Role { get; set; }

        public int ApplicationId { get; set; }
        public Application Application { get; set; }

        public int ActivitId { get; set; }
        public Activity Activity { get; set; }
    }

我基本上想要实现以下表格映射

Role    Application Activity
1         1          1
1         1          2
2         1          1
2         2          1

如果我的实体设计对于这种方法是正确的，你能帮助我吗？

这是我为三联接表创建密钥的代码。

 modelBuilder.Entity<RoleApplicationActivity>()
               .HasKey(ur => new { ur.RoleId, ur.ApplicationId, ur.ActivitId });

编辑：

看起来我找到了答案。我在sql server和Scaffold-DbContext中生成了我的设计，为我生成代码。

以下是它生成的代码。

public partial class Activity
    {
        public Activity()
        {
            RoleApplicationActivity = new HashSet<RoleApplicationActivity>();
        }

        public int Id { get; set; }
        public string Name { get; set; }

        public ICollection<RoleApplicationActivity> RoleApplicationActivity { get; set; }
    }

 public partial class Application
    {
        public Application()
        {
            RoleApplicationActivity = new HashSet<RoleApplicationActivity>();
        }

        public string Name { get; set; }
        public int Id { get; set; }

        public ICollection<RoleApplicationActivity> RoleApplicationActivity { get; set; }
    }
 public partial class Role
    {
        public Role()
        {
            RoleApplicationActivity = new HashSet<RoleApplicationActivity>();
        }

        public string Name { get; set; }
        public int Id { get; set; }

        public ICollection<RoleApplicationActivity> RoleApplicationActivity { get; set; }
    }

 public partial class RoleApplicationActivity
    {
        public int Id { get; set; }
        public int RoleId { get; set; }
        public int ApplicationId { get; set; }
        public int ActivityId { get; set; }

        public Activity Activity { get; set; }
        public Application Application { get; set; }
        public Role Role { get; set; }
    }

protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<Activity>(entity =>
            {
                entity.Property(e => e.Id).ValueGeneratedNever();

                entity.Property(e => e.Name)
                    .IsRequired()
                    .HasColumnType("nchar(10)");
            });

            modelBuilder.Entity<Application>(entity =>
            {
                entity.Property(e => e.Id).ValueGeneratedNever();

                entity.Property(e => e.Name)
                    .IsRequired()
                    .HasColumnType("nchar(10)");
            });

            modelBuilder.Entity<Role>(entity =>
            {
                entity.Property(e => e.Id).ValueGeneratedNever();

                entity.Property(e => e.Name)
                    .IsRequired()
                    .HasColumnType("nchar(50)");
            });

            modelBuilder.Entity<RoleApplicationActivity>(entity =>
            {
                entity.HasOne(d => d.Activity)
                    .WithMany(p => p.RoleApplicationActivity)
                    .HasForeignKey(d => d.ActivityId)
                    .OnDelete(DeleteBehavior.ClientSetNull)
                    .HasConstraintName("FK_RoleApplicationActivity_Activity");

                entity.HasOne(d => d.Application)
                    .WithMany(p => p.RoleApplicationActivity)
                    .HasForeignKey(d => d.ApplicationId)
                    .OnDelete(DeleteBehavior.ClientSetNull)
                    .HasConstraintName("FK_RoleApplicationActivity_Application");

                entity.HasOne(d => d.Role)
                    .WithMany(p => p.RoleApplicationActivity)
                    .HasForeignKey(d => d.RoleId)
                    .OnDelete(DeleteBehavior.ClientSetNull)
                    .HasConstraintName("FK_RoleApplicationActivity_Role");
            });
        }