The Entity create an additional table for many to-many relationships - entity-framework

Question

Today I got a question about how to create a many to many mapping using Entity Framework Code First fluent api.
The problem is that the entity create an additional table beyond that was set for me.
public class Person
{
public Person()
{
courses = new HashSet<Course>();
}
public int PersonID { get; set; }
public String Name { get; set; }
public ICollection<Course> courses { get; set; }
}
public class Course
{
public Course()
{
people = new HashSet<Person>();
}
public int CourseID { get; set; }
public String Name { get; set; }
public ICollection<Person> people { get; set; }
}
public class PersonCourse
{
public int fk_CourseID { get; set; }
public virtual Course course { get; set; }
public int fk_PersonID { get; set; }
public virtual Person person { get; set; }
public String AnotherInformation { get; set; }
}
public class PersonDataConfiguration : EntityTypeConfiguration<Person>
{
public PersonDataConfiguration()
{
ToTable("Person");
Property(c => c.Name).IsRequired();
this.HasMany(c => c.courses).WithMany(t => t.people).Map(m => { m.MapLeftKey("CourseID"); m.MapRightKey("PersonID"); });
}
}
public class CourseDataConfiguration : EntityTypeConfiguration<Course>
{
public CourseDataConfiguration()
{
ToTable("Course");
Property(c => c.Name).IsRequired();
this.HasMany(c => c.people).WithMany(t => t.courses).Map(m => { m.MapLeftKey("PersonID"); m.MapRightKey("CourseID"); });
}
}
public class PersonCourseDataConfiguration : EntityTypeConfiguration<PersonCourse>
{
public PersonCourseDataConfiguration()
{
ToTable("PersonCourseX");
HasKey(c => new { c.fk_CourseID, c.fk_PersonID });
Property(c => c.AnotherInformation).IsRequired();
this.HasRequired(c => c.person).WithMany().HasForeignKey(t => t.fk_PersonID);
this.HasRequired(c => c.course).WithMany().HasForeignKey(t => t.fk_CourseID);
}
}
public class ProgramTesteContext : DbContext
{
public ProgramTesteContext()
: base("MyConnectionString")
{
}
public DbSet<Person> Person { get; set; }
public DbSet<Course> Course { get; set; }
public DbSet<PersonCourse> PersonCourse { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
modelBuilder.Conventions.Remove<OneToManyCascadeDeleteConvention>();
modelBuilder.Conventions.Remove<ManyToManyCascadeDeleteConvention>();
modelBuilder.Conventions.Remove<IncludeMetadataConvention>();
modelBuilder.Properties<String>()
.Configure(p => p.HasColumnType("varchar"));
modelBuilder.Properties<String>()
.Configure(p => p.HasMaxLength(100));
modelBuilder.Configurations.Add(new PersonDataConfiguration());
modelBuilder.Configurations.Add(new CourseDataConfiguration());
modelBuilder.Configurations.Add(new PersonCourseDataConfiguration());
}
}
The entity set up two tables for mapping:
PersonCourseX created by me and another CoursePerson table containing only foreign keys without anotherinformation field.
How to make this second table is not created?

Answer 1

Change PersonCourseDataConfiguration as follows:
public class PersonCourseDataConfiguration : EntityTypeConfiguration<PersonCourse>
{
public PersonCourseDataConfiguration()
{
ToTable("PersonCourseX");
HasKey(c => new { c.fk_CourseID, c.fk_PersonID });
Property(c => c.AnotherInformation).IsRequired();
this.HasRequired(c => c.person).WithMany(c => c.courses).HasForeignKey(t => t.fk_PersonID);
this.HasRequired(c => c.course).WithMany(c => c.people).HasForeignKey(t => t.fk_CourseID);
}
}
Remove the commented lines:
public class PersonDataConfiguration : EntityTypeConfiguration<Person>
{
public PersonDataConfiguration()
{
ToTable("Person");
Property(c => c.Name).IsRequired();
//this.HasMany(c => c.courses).WithMany(t => t.people).Map(m => { m.MapLeftKey("CourseID"); m.MapRightKey("PersonID"); });
}
}
public class CourseDataConfiguration : EntityTypeConfiguration<Course>
{
public CourseDataConfiguration()
{
ToTable("Course");
Property(c => c.Name).IsRequired();
//this.HasMany(c => c.people).WithMany(t => t.courses).Map(m => { m.MapLeftKey("PersonID"); m.MapRightKey("CourseID"); });
}
}
Change Person and Course as follows:
public class Person
{
//.. other properties
public ICollection<PersonCourse> courses { get; set; }
}
public class Course
{
//.. other properties
public ICollection<PersonCourse> people { get; set; }
}