(Group)Join if you can't use the ICollection

Question

Hi,

 

I have 2 table :(User and Service) with relation many to many

 

the EF create third table ServiceUserDiff

public partial class User
{
public int UserID { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public virtual ICollection<ServiceUserDiff> UserDiffToService { get; set; }
}
public partial class Service
{
public int CodeService { get; set; }
public string DesignationService { get; set; }
public virtual ICollection<ServiceUserDiff> ServiceToUserDiff { get; set; }
}
public partial class ServiceUserDiff
{
public Nullable<int> IdUserDiffService { get; set; }
public Nullable<int> IdServiceUserDiff { get; set; }
public Nullable<int> AttributaireON { get; set; }
public int IdDiff { get; set; }
public virtual Service ServiceDiff { get; set; }
public virtual User UserDiff { get; set; }
}

i create function to get information from 3 table

public List<ServiceUserDiff> GetAllServiceUserDiff()
{
var listServiceUserDiff = bd.Service.GroupJoin(bd.ServiceUserDiff,
service => service.CodeService,
serviceUserDiff => serviceUserDiff.IdServiceUserDiff,
(service, serviceUserDiff) => new
{
serviceCode = service.CodeService,
serviceDsg = service.DesignationService,
user = serviceUserDiff.Join(bd.User,
serviceUserDiffs => serviceUserDiffs.IdUserDiffService,
user => user.UserID,
(user, serviceUserDiffs) => new
{
IdUser = serviceUserDiffs.UserID,
NameLast = serviceUserDiffs.LastName,
NameFirst = serviceUserDiffs.FirstName
}).ToList(),
});
return listServiceUserDiff;
}

this function generates me the next error message:

 

Cannot implicitly convert type system linq IQueryable to system collections generic List

 

thanks for your help