Entity Framework many to many fluent API - entity-framework

Question

I'm working with an existing database whose schema is fixed.
There are 3 many-to-many relations, Contact-Group, Contact-Department and Contact-Team.
There is a common table, ContactRelation that acts as the middle table for all 3 relations.
public class Contact
{
[Column("CtcID")]
public int Id { get; set; }
[Column("CtcFirstName")]
public string FirstName { get; set; }
[Column("CtcFamilyName")]
public string LastName { get; set; }
public virtual ICollection<ContactRelation> GroupRelations { get; set; }
public virtual ICollection<ContactRelation> DepartmentRelations { get; set; }
public virtual ICollection<ContactRelation> TeamRelations { get; set; }
}
public class Group
{
[Key, Column("GRID")]
public int Id { get; set; }
[Column("GRName")]
public string Name { get; set; }
public virtual ICollection<ContactRelation> ContactRelations { get; set; }
}
public class Department
{
[Key, Column("DEPID")]
public int Id { get; set; }
[Column("DEPName")]
public string Name { get; set; }
public virtual ICollection<ContactRelation> ContactRelations { get; set; }
}
public class Team
{
[Key, Column("TMID")]
public int Id { get; set; }
[Column("TransCode")]
public string TransCode { get; set; }
public virtual ICollection<ContactRelation> ContactRelations { get; set; }
}
public class ContactRelation
{
[Key]
[Column("CtcRelnID")]
public int Id { get; set; }
[Column("GRID")]
public int GroupId { get; set; }
[Column("DEPID")]
public int DepartmentId { get; set; }
[Column("TMID")]
public int TeamId { get; set; }
[Column("CUCtcID")]
public int ContactId { get; set; }
[Column("RCode")]
public string RoleCode { get; set; }
}
In my mapping, I have the following code:
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Group>()
.HasMany(g => g.ContactRelations)
.WithRequired()
.HasForeignKey(r => r.GroupId);
modelBuilder.Entity<Department>()
.HasMany(c => c.ContactRelations)
.WithRequired()
.HasForeignKey(r => r.DepartmentId);
modelBuilder.Entity<Team>()
.HasMany(s => s.ContactRelations)
.WithRequired()
.HasForeignKey(r => r.TeamId);
modelBuilder.Entity<Contact>()
.HasMany(c => c.GroupRelations)
.WithRequired()
.HasForeignKey(r => r.ContactId);
modelBuilder.Entity<Contact>()
.HasMany(c => c.DepartmentRelations)
.WithRequired()
.HasForeignKey(r => r.ContactId);
modelBuilder.Entity<Contact>()
.HasMany(c => c.TeamRelations)
.WithRequired()
.HasForeignKey(r => r.ContactId);
}
I then try to execute the following query:
var ctc = repo.Contacts
.Include("GroupRelations")
.Include("DepartmentRelations")
.FirstOrDefault(c => c.FirstName.ToLower() == "jason");
and I keep getting error:
System.Data.SqlClient.SqlException:
Invalid column name 'Contact_Id1'.
Invalid column name 'Contact_Id'.
Invalid column name 'Contact_Id1'.
Invalid column name 'Contact_Id2'.
I read somewhere that a table cannot participate in more than one many-to-many relations. Is that true? Is it because the ContactRelation table is used more than once that I'm getting this error?
If so, what's the correct way to map these relations, without modifying the database schema.?
PS: I'm working with EF6.1
Thanks for your help.

Answer 1

Remove this mapping
modelBuilder.Entity<Contact>()
.HasMany(c => c.TeamRelations)
.WithRequired()
.HasForeignKey(r => r.ContactId);
and then try executing your query.