dotnetcore EF many-to-many mapping

    class Student
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public List<Teacher> Teachers { get; } = new List<Teacher>();
    }

    class StudentConfig : IEntityTypeConfiguration<Student>
    {
        public void Configure(EntityTypeBuilder<Student> builder)
        {
            builder.ToTable("student");

            builder.Property(e => e.Name).HasColumnType("nvarchar(50)").IsRequired();
        }
    }

    class Teacher
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public List<Student> Students { get; } = new List<Student>();
    }

    class TeacherConfig : IEntityTypeConfiguration<Teacher>
    {
        public void Configure(EntityTypeBuilder<Teacher> builder)
        {
            builder.ToTable("teacher");

            builder.Property(e => e.Name).HasColumnType("nvarchar(50)").IsRequired();
            // 使用hasMany()/withMany()+指定中间表
            builder.HasMany(t => t.Students).WithMany(s => s.Teachers).UsingEntity(b => b.ToTable("teacher_student"));
        }
    }

    class MyDbContext : DbContext
    {
        public DbSet<Teacher> Teachers { get; set; }
        public DbSet<Student> Students { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            base.OnConfiguring(optionsBuilder);

            ILoggerFactory loggerFactory = LoggerFactory.Create(builder => builder.AddConsole());

            optionsBuilder.UseLoggerFactory(loggerFactory); // output sql script to log.
            //optionsBuilder.LogTo(Console.WriteLine);
            optionsBuilder.UseSqlServer("Server=.;Database=demo02;Trusted_Connection=True;MultipleActiveResultSets=True");
        }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);
            modelBuilder.ApplyConfigurationsFromAssembly(this.GetType().Assembly);
        }
    }

    class Program
    {
        static async Task Main(string[] args)
        {
            using (MyDbContext ctx = new MyDbContext())
            {
                await GetStudents(ctx);
            }
        }

        private static Task GetStudents(MyDbContext ctx)
        {
            Student[] students = ctx.Students.Include(s => s.Teachers).Where(_ => true).ToArray();

            foreach (Student s in students)
            {
                Console.WriteLine(s.Name);
                foreach (Teacher t in s.Teachers)
                {
                    Console.WriteLine($"    {t.Name}");
                }
            }

            return Task.CompletedTask;
        }

        private static async Task SaveStudentTeachers(MyDbContext ctx)
        {
            Student s1 = new Student { Name = "张三" };
            Student s2 = new Student { Name = "李四" };
            Student s3 = new Student { Name = "王五" };

            Teacher t1 = new Teacher { Name = "tom" };
            Teacher t2 = new Teacher { Name = "mike" };
            Teacher t3 = new Teacher { Name = "jack" };

            s1.Teachers.AddRange(new Teacher[] { t1, t2 });
            s2.Teachers.AddRange(new Teacher[] { t2, t3 });
            s3.Teachers.AddRange(new Teacher[] { t1, t2, t3 });

            ctx.Students.AddRange(new Student[] { s1, s2, s3 });
            await ctx.SaveChangesAsync();
        }
    }

标签：Name,many,builder,EF,public,dotnetcore,Student,new,Teacher
来源： https://www.cnblogs.com/mryux/p/15857340.html