Question

I am trying to expose the linked class that EF code first automatically creates in many to many relationships as a separate object because that linked object needs to be referenced in other classes, however I seem to have a problem with getting the data that exists in the database.

I’ve got the following 3 objects:

 public class Role : Entity
{
    public virtual ICollection<User> Users { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
    public virtual ICollection<Permission> Permissions { get; set; }
}

public class User: Entity
{
    public string FirstName { get; set; }
    public string MiddleName { get; set; }
    public string LastName { get; set; }

    public virtual ICollection<Role> Roles { get; set; }
 }

 public class UserRole : Entity
{
    public User User { get; set; }
    public Role Role { get; set; }
}

This creates the following tables:

Now I can see the problem is that it is creating a RoleUsers table, when it shouldn’t and should just use my UserRoles table. How can I force the linked table to be UserRoles so that I can have that linked object exposed in EF so I can use it in other objects?

Also, how would I be traversing the objects then when writing queries? Would I still be able to use User.Roles.Any(y => y.Name == “blah”), or would I now have to query by going User.UserRoles.Any(y => y.Role.Name == “blah”)? I suppose it isn’t possible to maintain the transparent linking while simultaneously exposing the linked object?

Edit: One of the classes that references UserRole as a navigation property looks like this:

 public class UserRoleEntity : Entity
{
    public UserRole UserRole { get; set; }
    public Guid EntityId { get; set; }
    public EntityType EntityType { get; set; }
}

I don’t want to individually store the User and Role object in this class because then they are not tightly coupled and data could be orphaned.

Answer 1

You don’t need to explicitly create UserRole entity in your code. since you have the navigational property of Roles in Users and Users in Roles, EF will automatically create a relationship between them.

EDIT : If you want to create the link table and use that as a property of another class, you can do it like this.

public class User 
{
    public int UserID { set; get; }
    public string FirstName { get; set; }     
    public string LastName { get; set; }
    public virtual ICollection<UserRole> UserRoles { get; set; }      
}
public class Role 
{      
    public int RoleID { set;get;}
    public string Name { get; set; }
    public string Description { get; set; }
    public virtual ICollection<UserRole> UserRoles { get; set; }
}
public class UserRole 
{
    public int UserRoleID { set; get; }
    public virtual User User { get; set; }
    public virtual Role Role { get; set; }
}
public class AnotherEntity
{
    public int ID { set; get; }
    public int UserRoleID { set; get; }     
}

and you will have your tables created like this

And you are correct, You have to access it like this

 StringBuilder stRoleNames = new StringBuilder();
 var user1 = dbContext.Users.Where(x => x.UserID == 34).SingleOrDefault();
 var userRoles = user1.UserRoles;
 foreach (var userRole in userRoles)
 {
     stRoleNames.Append(userRole.Role.Name);
 }