如何使用实体框架提交具有多对多关系的对象？

// 定义学生实体类
public class Student
{
    public int StudentId { get; set; }
    public string Name { get; set; }
    public ICollection<Course> Courses { get; set; }
}

// 定义课程实体类
public class Course
{
    public int CourseId { get; set; }
    public string Name { get; set; }
    public ICollection<Student> Students { get; set; }
}

// 创建数据库上下文类
public class SchoolContext : DbContext
{
    public DbSet<Student> Students { get; set; }
    public DbSet<Course> Courses { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        // 配置多对多关系
        modelBuilder.Entity<Student>()
            .HasMany(s => s.Courses)
            .WithMany(c => c.Students)
            .Map(cs =>
            {
                cs.MapLeftKey("StudentId");
                cs.MapRightKey("CourseId");
                cs.ToTable("StudentCourse");
            });
    }
}

// 添加数据
using (var context = new SchoolContext())
{
    var student1 = new Student { Name = "John" };
    var student2 = new Student { Name = "Jane" };

    var course1 = new Course { Name = "Math" };
    var course2 = new Course { Name = "Science" };

    student1.Courses.Add(course1);
    student1.Courses.Add(course2);
    student2.Courses.Add(course1);

    context.Students.Add(student1);
    context.Students.Add(student2);

    context.SaveChanges();
}