Question

I need a way to create an extension method off of an IEnumerable that will allow me to return a list of SelectListItem’s.

For example

    public class Role
    {
        public string Name {get;set;}
        public string RoleUID {get;set;}
    }
    IEnumerable<Role> Roles = .../*Get Roles From Database*/
    var selectItemList = Roles.ToSelectItemList(p => p.RoleUID,r => r.Name);

this would give me a SelectItemList with the Name being the display, and the RoleUID being the value.

IMPORTANT I want this to be generic so I can create it with any two properties off of an object, not just an object of type Role.

How can I do this?

I imagine something like the following

 public static List<SelectItemList> ToSelectItemList<T,V,K>(this IEnumerable<T>,Func<T,V,K> k)

or something, I obviously know that would be incorrect.

Answer 1

Why not just combine the existing Select and ToList methods?

var selectItemList = Roles
  .Select(p => new SelectListItem { Value = p.RoleUID, Text = p.Name })
  .ToList();

If you want to specifically put it into one method then you could define ToSelectListItem as a combination of those two methods.

public static List<SelectListItem> ToSelectListItem<T>(
  this IEnumerable<T> enumerable,
  Func<T, string> getText,
  Func<T, string> getValue) {

  return enumerable
    .Select(x => new SelectListItem { Text = getText(x), Value = getValue(x) })
    .ToList();
}