Entity Framework modify models - asp.net

Question

I'm trying to modify the model entity which is sent to the CreateEmployee Method as a parameter to be modified.
public void CreateEmployee(string roleName, EmployeeModel emp)
{
string roleName == "user";
emp.Roles.Select(e => new RoleModel { RoleName = roleName });
AddEmployee(emp);
}
this is how models looks like....
And it give me an error saying
Model does not contain a definition for 'Select' and 'Select' accepting a first argument of type Model could be found....
I have tried using the 'Where' method as well, but still give the same error..
emp.Roles.Where(e => e.RoleName == roleName)

Answer 1

You have some errors in your code,
use = not == for assignment
the selected roles does not used
Linq query functions like Select and Where apply to IEnumerable the Roles property is of type RoleModel not IEnumerable<RoleModel>
so:
public class EmployeeModel
{
//some code
public ICollection<RoleModel> Roles{ get; set; }
}
using System.Linq;
public void CreateEmployee(string roleName, EmployeeModel emp)
{
string roleName = "user";
var empRoles = emp.Roles.Select(e => new RoleModel { RoleName = roleName });
AddEmployee(emp);
}
Edit:
If you want to have one role per employee at most, the relationship between Role and Employee became one-to-many(each role has n employee)
if Role is optional for employee:
public class EmployeeModel
{
//some code
public short? RoleId { get; set; }//nullable foreign key
public virtual RoleModel { get; set; } //Navigation property
}
public class RoleModel
{
//some code
public ICollection<Employee> Employees{ get; set; }
}
But, if Role is required for Employee you must change the foreign key to:
public short RoleId { get; set; }//non-null foreign key
For getting an Employee's Role you do not need to use Select or Where on navigation property, just use employee.Role.
Finally for querying Role's employees you can use Select, Where, ... as mentioned before.