Question

我的模特学生有他所有科目的集合，每个科目都收集了教育比赛。

public class Subject
{
     public int SubjectID { get; set; }
     public string SubjectName {get; set; }
     public ICollection<Student> { get; set; }
}

public class EducationalMatches
{
     public int EducationalMatchesID { get; set; }
     public int Number { get; set; }
     public string Name { get; set; }
}

public class Student
{
     public int StudentID { get; set; }
     public Icollection<AllStudentSubjects> AllStudentSubjects{ get; set; }
}


public class AllStudentSubject
{
     public int AllStudentSubjectID { get; set; }
     public Subject Subject { get; set; }
     public ICollection<EducationalMatches> Educations { get; set; }
}

我希望在DB中会出现一个看起来像这样的表：

tableID
StudentID
SubjectID
EducationMatchesID

但没有出现这样的表格。有谁有想法？

Answer 1

拥有模型是不够的，您需要覆盖OnModelCreating方法（默认情况下它是空的）。加上EF希望能够“扭转”＃39;例如，如果学生有一个主题集合，主题应该有一个学生集合（多对多关系）

在AllStudentSubject的情况下，它应该是这样的（没有测试）

protected override void OnModelCreating(DbModelBuilder modelBuilder) { modelBuilder.Entity<AllStudentSubject>() .HasKey(a => a.AllStudentSubjectID ) //Primary key, I prefer [Key] attribute, but this also works .HasRequired(a => a.Student) //Property in AllStudentSubject .WithMany(s => s.AllStudentSubjects) // Collection property in Student class .HasForeignKey(a => a.StudentId)//Second property in AllStudentSubject //For Student, you do not have to write this all again, just the primary key modelBuilder.Entity<Student>() .HasKey(a => a.StudentId ) //I like to move 'simple' declarations like this to the top }

对于其他两个实体，您必须这样做。这是一个伟大的article，其中包含所有概念的解释

EF CF如何创建一个具有三个外键的表

1 个答案: