c# - 播种多对多数据

Question

您好，我正在尝试为我的项目创建一些种子，但我无法将多对多关系数据播种到数据库。

我的数据库是这样的:

在 TeacherSkills 中，Teacher_ID 和 Skill_ID 是其类(class)表的外键。

我的播种机是这样的

protected override void Seed(Ability_Examen_ASP.Models.AbilityDbContext context)
    {
        if (!context.Skills.Any())
        {
            context.Skills.Add(new Models.Skill { SkillName = "PHP" });
            context.Skills.Add(new Models.Skill { SkillName = "Java" });
            context.Skills.Add(new Models.Skill { SkillName = "Frans" });
            context.Skills.Add(new Models.Skill { SkillName = "Drupal" });
        }

        if (!context.Teachers.Any())
        {
            context.Teachers.Add(new Models.Teacher
            {
                FirstName = "Joris",
                LastName = "Hens",
                Campus = "Kruidtuin",
                Password = "testpass",
                Email = "Joris.Hens@"
            });
            context.Teachers.Add(new Models.Teacher
            {
                FirstName = "Anne",
                LastName = "Van Goetem",
                Campus = "Kruidtuin",
                Password = "testpass",
                Email = "Anne.Vangoetem@"
            });
            context.Teachers.Add(new Models.Teacher
            {
                FirstName = "Sofie",
                LastName = "Krekels",
                Campus = "De Ham",
                Password = "testpass",
                Email = "Sofie.Krekels@"
            });
            context.Teachers.Add(new Models.Teacher
            {
                FirstName = "Robby",
                LastName = "Vanelderen",
                Campus = "De Vest",
                Password = "testpass",
                Email = "Robby.Vanelderen@"
            });
        }

        if (!context.TeacherSkills.Any())
        {
            context.TeacherSkills.Add(new Models.TeacherSkill
            {
                Teacher_ID = 1,
                Skill_ID = 1,
            });
            context.TeacherSkills.Add(new Models.TeacherSkill
            {
                Teacher_ID = 1,
                Skill_ID = 4,
            });
            context.TeacherSkills.Add(new Models.TeacherSkill
            {
                Teacher_ID = 2,
                Skill_ID = 2,
            });
            context.TeacherSkills.Add(new Models.TeacherSkill
            {
                Teacher_ID = 3,
                Skill_ID = 3,
            });
            context.TeacherSkills.Add(new Models.TeacherSkill
            {
                Teacher_ID = 4,
                Skill_ID = 4,
            });
        }

    }

老师和技能种子没有任何问题，但我无法将任何技能种子给老师。

它没有给我任何错误，我也不确定哪里出了问题。

希望大家帮帮忙，谢谢!

Answer 1

添加调用

context.SaveChanges();  

在你培养教师的地方和你要培养教师技能的地方之间。这应该提交 Skills 和 Teachers 集合，这样您对键列(标识值)的假设将被 INSERT 执行时实际生成的那些所取代。

此外，可以在 TeacherSkills 构造函数中检索和使用实际教师和技能的 ID 值，以摆脱种子代码中的“魔数(Magic Number)”1-4。