Entity Framework 多对多关系 3 类

Question

您好，我有以下三个 classes。我正在尝试使用三个 classes 实现多对多映射。我已经实现了两个 class 之间的多对多关系，但我正试图在混合中获得另一个 class。下面是我拥有的 classes 和我试图实现的关系的 class 表示。

public class Person
{
    public int ID { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string EmployeeId { get; set; }
    public ICollection<Department> Departments { get; set; }
}

public class Department
{
    public int ID { get; set; }
    public string Name { get; set; }
    public string DepartmentCode { get; set; }
    public string Description { get; set; }
    public ICollection<Person> Members { get; set; }
}

public class Role
{
    public int ID { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
}

关于如何实现以下目标的任何提示都会有所帮助。

public class PersonRoleDepartment
{
    public int PersonID { get; set; }
    public int DepartmentID{ get; set; }
    public int RoleID { get; set; }
}

Answer 1

public class Person
{
    public int Id { get; set; }
    public ICollection<PersonDepartmentRole> DepartmentRoles { get; set; }
}

public class Department
{
    public int Id { get; set; }
    public ICollection<PersonDepartmentRole> PersonRoles { get; set; }
}

public class Role
{
    public int Id { get; set; }
    public ICollection<PersonDepartmentRole> PersonDepartments { get; set; }
}

public class PersonDepartmentRole
{
    [Key, Column( Order = 0 )]
    public int PersonId { get; set; }
    [ForeignKey( "PersonId" )]
    [Required]
    public virtual Person Person { get; set; }

    [Key, Column( Order = 1 )]
    public int DepartmentId { get; set; }
    [ForeignKey( "DepartmentId" )]
    [Required]
    public virtual Department Department { get; set; }

    [Key, Column( Order = 2 )]
    public int RoleId { get; set; }
    [ForeignKey( "RoleId" )]
    [Required]
    public virtual Role Role { get; set; }
}

流畅API 配置：

var pdrConfig = modelBuilder.Entity<PersonDepartmentRole>()
    .HasKey( pdr => new
    {
        pdr.PersonId,
        pdr.DepartmentId,
        pdr.RoleId
    } ); 

pdrConfig.HasRequired( pdr => pdr.Department )
    .WithMany( d => d.PersonRoles )
    .HasForeignKey( pdr => pdr.DepartmentId );

pdrConfig.HasRequired( pdr => pdr.Person )
    .WithMany( p => p.DepartmentRoles )
    .HasForeignKey( pdr => pdr.PersonId );

pdrConfig.HasRequired( pdr => pdr.Role )
    .WithMany( r => r.PersonDepartments )
    .HasForeignKey( pdr => pdr.RoleId );

注意：从任何主要实体到其他实体的所有引用都应通过您的联结实体 PersonDepartmentRole - 否则，可能会出现数据不一致（例如，我将 Department 添加到 Person 以及相应的 PersonDepartmentRole 记录到数据库，但随后我从 Person 实体中删除了 Department - PersonDepartmentRole 实体仍然存在）

相反，如果您想要一个人的所有部门：

db.Person.DepartmentRoles.Select( dr => dr.Department ).Distinct()

Answer 2

在这个构造中，一个人可以在一个部门但没有角色吗？或者，一个部门没有人，能发挥作用吗？如果没有，这怎么可能完成

Entity Framework 多对多关系 3 类

Entity Framework Many to Many Relationship 3 Classes

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