EF核心多个一对多关系

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

    public List<Employee> Employees { get; set; } = new List<Employee>();
}

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

    public int DepartmentId { get; set; }
    public Department Department { get; set; }
}

public class ApplicationDbContext : DbContext
{
    public DbSet<Department> Departments { get; set; }
    public DbSet<Employee> Employees { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Employee>()
            .HasOne(e => e.Department)
            .WithMany(d => d.Employees)
            .HasForeignKey(e => e.DepartmentId);
    }
}

var department = context.Departments
    .Include(d => d.Employees)
    .FirstOrDefault(d => d.Id == departmentId);

modelBuilder.Entity<Employee>()
    .HasOne(e => e.Department)
    .WithMany(d => d.Employees)
    .HasForeignKey(e => e.DepartmentId)
    .OnDelete(DeleteBehavior.Cascade); // 可选：配置级联删除