When setting up a many-to-many relationship with Code First approach, by default the join table only includes 2 columns (FK to PK of the 2 tables).
1) Is it possible/How can I setup a join table that will include some additional fields, and 2) how do I fill these values via code?
For example:
class Student
{
public int Id { get; set; }
public string Name { get; set; }
public List<Course> Courses { get; set; }
}
class Course
{
public int Id { get; set; }
public string Name { get; set; }
public List<Student> Students { get; set; }
}
class MyDbContext : DbContext
{
public DbSet<Student> Students { get; set; }
public DbSet<Course> Courses { get; set; }
}
A simple db with Students and Courses with a many-to-many relationship. However for each join Student-Course, I also want a field, for example: PercentComplete, that tracks how far a student is in each course.
How can this be achieved?
Thanks
This is a case for many-to-many relationship with additional information. You will need to create a new entity called, let's say Enrollments. Then, you will need to set 1-to-Many relationships between Student - Enrollment and Course - Enrollment entities.
public class Student
{
[Key]
public int Id { get; set; }
public string Name { get; set; }
public List<Enrollment> Enrollments { get; set; }//each student can have many enrollments
}
public class Course
{
[Key]
public int Id { get; set; }
public string Name { get; set; }
public List<Enrollment> Enrollments { get; set; }//each course can have many enrollments
}
public class Enrollment
{
public int EnrollmentId { get; set; }
public int PercentComplete{ get; set; }
public Course Course { get; set; } //each single enrollment involves one course
public Student Student { get; set; } //each single enrollment involves one student
}
You can find a detailed example here:
https://practiceaspnet.wordpress.com/2015/11/09/many-to-many-relationships-with-additional-fields/