Linq version of string array any in enum list

Question

Currently I have:

public enum ApplicationRoles
{
        Undefined = 0,
        Basic = 1,
        Admin = 2
}

// within a method:

bool? isAuthorized = null;
string[] allowedRoles = { "Admin" };
List<ApplicationRoles> userRoles = new List<ApplicationRoles>();

userRoles.Add(ApplicationRoles.Admin); 

foreach (string role in allowedRoles)
{
   foreach (ApplicationRoles appRole in userRoles)
   {
     if (appRole != ApplicationRoles.Undefined)
         isAuthorized = role.ToLower() == appRole.ToString().ToLower();
   }

   if ((bool)isAuthorized)
     break;
}

isAuthorized would return true in this example.

How can this be converted to a Linq statement?

Answer 1

You are looking for Any method:

allowedRoles
.Any(role => user.Roles.Any(r => r != ApplicationRoles.Undefined &&
                                 role.ToLower() == r.ToString().ToLower()));

If you wanna check only for one role there is no need for allowedRoles array:

user.Roles.Any(r => r.ToLower() == "admin");

Answer 2

You shouldn't store any of your values as hardcoded strings; that's what the enums are for, after all.

var allowedRoles = new HashSet<ApplicationRoles> { ApplicationRoles.Admin };
bool isAuthorized = userRoles.Any(r => allowedRoles.Contains(r));

This approach also works fine with arrays.

var allowedRoles = new[] { ApplicationRoles.Admin };
var userRoles = new[] { ApplicationRoles.Basic };
bool isAuthorized = userRoles.Any(r => allowedRoles.Contains(r));

Answer 3

What about

var allowedRoles = Enum.GetValues(typeof(ApplicationRoles))
    .Cast<ApplicationRoles>()
    .Except(ApplicationRoles.Undefinied); // allow all except undefined

bool isAuthorized = userRoles.Any(r => allowedRoles.Contains(r));

this way you don't need to mess with any string comparison.