EF使用流利的api创建可选关系

Question

这些是我的课程：

public class Department
{
    [Key]
    [Column("Department_Id")]
    public int DepartmentId { get; set; }

    [Required]
    [Column("Name")]
    public string Name { get; set; }

    [Column("Manager_Id")]
    public int? ManagerId { get; set; }

    [Column("Parent_Department_Id")]
    public int? ParentDeptId { get; set; }

    public virtual ICollection<Department> ChildDepartments { get; set; }

    public virtual Department ParentDepartment { get; set; }

    public virtual Employee Manager { get; set; }
}

public class Employee
{
    [Key]
    [Column("Employee_Id")]
    public int Id { get; set; }

    [Required]
    [Column("First_Name")]
    public string FirstName { get; set; }

    [Required]
    [Column("Last_Name")]
    public string LastName { get; set; }

    [Required]
    [Column("Job_Title_Id")]
    [ForeignKey("JobTitle")]
    public int? JobTitleId { get; set; }

    [Column("Manager_Id")]
    public int? ManagerId { get; set; }

    [Required]
    [Column("Department_Id")]
    public int? DepartmentId { get; set; }

    public virtual Department Department { get; set; }

    public virtual JobTitle JobTitle { get; set; }
}

现在在部门中，经理是可选的。如何使用 fluent api 建立这种关系？我想我需要使用modelBuilder.Entity<Department>().HasOptional(e => e.Manager)，但不知道接下来应该做什么。我做错了什么？

更新： 如果这有什么不同，我已经为我的部门准备了这段代码：

modelBuilder.Entity<Department>()
            .HasMany(e => e.ChildDepartments)
            .WithOptional(e => e.ParentDepartment)
            .HasForeignKey(e => e.ParentDeptId);

Answer 1

你需要完成那个关系

 modelBuilder.Entity<Department>().HasOptional(e => e.Manager).WithOptionalDependent();