Entity Framework Finding Entity via Foreign Keys - entity-framework

Question

I'm assuming this is bread & butter for most..
I have Roles, Permissions, and a RolePermissions entity to model many-to-many relationship.
public class RolePermission
{
[Key]
public int ID { get; set; }
//[Key, ForeignKey("Role"), Column(Order = 0)]
public int RoleID { get; set; }
//[Key, ForeignKey("Permission"), Column(Order = 1)]
public int PermissionID { get; set; }
//Navigational Properties
public virtual Role role { get; set; }
public virtual Permission permission { get; set; }
}
I have an ActionResult to remove a given RolePermission, based on the RoleID and PermissionId that are passed in.
public ActionResult Remove(int Roleid, int Permissionid)
{
RolePermission rolepermission = db.RolePermissions
.Include(p => p.PermissionID == Permissionid)
.SingleOrDefault(p => p.RoleID == Roleid);
db.RolePermissions.Remove(rolepermission);
db.SaveChanges();
return RedirectToAction("Index");
}
The above RolePermission rolepermission.. statement fails with
The Include path expression must refer to a navigation property defined on the type. Use dotted paths for reference navigation properties and the Select operator for collection navigation properties.
Parameter name: path
.. which I'm not suprised, as it has one hell of a code smell to start with.
What I'm after is the equivalent of
Delete from RolePermission
Where RoleID = roleid
AND PermissionID = permissionid
Any guidance?
Many thanks

Answer 1

Since you have the RolePermission exposed as an entity (which is a bit unusual for a many-to-many relationship) you should be able to just query for the record in the join table and delete it:
public ActionResult Remove(int Roleid, int Permissionid)
{
RolePermission rolepermission = db.RolePermissions
.SingleOrDefault(rp => rp.RoleID == Roleid
&& rp.PermissionID == Permissionid);
if (rolepermission != null)
{
db.RolePermissions.Remove(rolepermission);
db.SaveChanges();
}
return RedirectToAction("Index");
}