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ef核心2.1多对多

ef-core-2.1 c#

Rick Hodder · 技术社区 · 7 年前

我有4个表,我试图在efcore2.1中创建它们之间的关系

一部作品有一个或多个角色。e、 g.一部名为“汉密尔顿”的作品有一个人担任导演,

Production
ProductionId     Name        
------------     -----------
PR1               Hamilton

Person
PersonId         Name
--------         -----------
P1               Rick
P2               Chris
P3               Dan

Role
RoleId           Name
----------       -----------
R1               Director
R2               Choreographer
R3               Actor

ProductionRolePerson
ProductionId    PersonId    RoleId
------------    --------    ------
PR1             P1 (Rick)   R1 (Director)
PR1             P2 (Chris)  R2 (Choreographer)
PR1             P3 (Dan)    R3 (Actor)


Production 
    | 1
    | *
ProductionPersonRole
| *             | *
| 1             | 1
Person         Role

我想不出建立一对多关系的正确方法。

以下是我开设的课程:

 public class Production 
    {
        public int ProductionId { get; set; }
        public List<ProductionPersonRole> Roles { get; set; }
    }

    public class Person 
    {
        public int PersonId { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }

        public ICollection<ProductionPersonRole> ProductionPersonRoles { get; set; }
    }

public class Role
    {
        public int RoldId { get; set; }
        public string Name {get;set;}
        public ICollection<ProductionPersonRole> Jobs { get; set; }
    }

public class ProductionPersonRole
    {
        public Production Production { get; set; }
        public Person Person { get; set; }
        public Role Role { get; set; }
    }

以下是DbContext类:

    public class MyContext : DbContext
        {
            public DbSet<Production> Productions { get; set; }
            public DbSet<ProductionPersonRole> ProductionPersonRoles { get; set; }
            public DbSet<Role> Roles { get; set; }
            public DbSet<Person> Persons { get; set; }

            public MyContext(): base()
            {

            }

            public MyContext(DbContextOptions options): base(options)
            {

            }

            protected override void OnModelCreating(ModelBuilder modelBuilder)
            {
                modelBuilder.Entity<ProductionPersonRole>()
                    .HasKey(ppr => new {ppr.Production.ProductionId, ppr.Person.PersonId, ppr.Role.RoldId});

                modelBuilder.Entity<ProductionPersonRole>()
                    .HasOne(ppr => ppr.Production)
                    .WithMany(ppr => ppr.Roles)
                    .HasForeignKey(ppr => ppr.Production.ProductionId);

                modelBuilder.Entity<ProductionPersonRole>()
                    .HasOne(ppr => ppr.Person)
                    .WithMany(ppr => ppr.ProductionPersonRoles)
                    .HasForeignKey(ppr => ppr.Person.PersonId);

                modelBuilder.Entity<ProductionPersonRole>()
                    .HasOne(ppr => ppr.Role)
                    .WithMany(ppr => ppr.Jobs)
                    .HasForeignKey(ppr => ppr.Role.RoleId);

                base.OnModelCreating(modelBuilder);
            }
}

我的方向正确吗?

2 回复 | 直到 7 年前

Ivan Stoev 7 年前

设计还可以。但流畅的配置并非如此。EF Core不允许在fluent API中使用嵌套属性,因此 HasKey HasForeignKey 方法的使用将导致运行时异常。

要求

虽然可以只使用阴影属性配置复合PK(例如,了解FK属性命名的EF核心约定) public Person Person int PersonId ):

modelBuilder.Entity<ProductionPersonRole>()
     .HasKey("ProductionId", "PersonId", "RoleId");

public class ProductionPersonRole
{
    public int ProductionId { get; set; }
    public int PersonId { get; set; }
    public int RoleId { get; set; }
    public Production Production { get; set; }
    public Person Person { get; set; }
    public Role Role { get; set; }
}

而是使用以下配置:

modelBuilder.Entity<ProductionPersonRole>()
     .HasKey(ppr => new { ppr.ProductionId, ppr.PersonId, ppr.RoleId });

它不仅避免使用硬编码字符串,而且在断开连接的情况下插入/删除链接时也非常有用。

Inline Instructions. 7 年前

是的,只需验证数据库架构。因为如果不正确,EF将创建具有不同体系结构的DB。