Foreign key constraint may cause cycles or multiple cascade paths?

Question

I have a problem when I try to add constraints to my tables. I get the error:

Introducing FOREIGN KEY constraint \'FK74988DB24B3C886\' on table \'Empl

Answer 1

This is because Emplyee might have Collection of other entity say Qualifications and Qualification might have some other collection Universities e.g.

public class Employee{
public virtual ICollection Qualifications {get;set;}

}

public class Qualification{

public Employee Employee {get;set;}

public virtual ICollection Universities {get;set;}

}

public class University{

public Qualification Qualification {get;set;}

}

On DataContext it could be like below

protected override void OnModelCreating(DbModelBuilder modelBuilder){

modelBuilder.Entity().HasRequired(x=> x.Employee).WithMany(e => e.Qualifications);
modelBuilder.Entity.HasRequired(x => x.Qualification).WithMany(e => e.Universities);

}

in this case there is chain from Employee to Qualification and From Qualification to Universities. So it was throwing same exception to me.

It worked for me when I changed

    modelBuilder.Entity().**HasRequired**(x=> x.Employee).WithMany(e => e.Qualifications); 

To

    modelBuilder.Entity().**HasOptional**(x=> x.Employee).WithMany(e => e.Qualifications);