LINQ: Find if one item in List appears in a string array

I have a string array and another object that has a list of objects, on of the properties is a string. 

public string[] allowedroles;

foreach (var role in allowedroles)
{
   if (user.RolesList.Exists(r => r.Name == role))
   {
      authorize = true;
      break; // if one match that break out of loop
   }
}

Is there a way to perform with just a LINQ statement, without the foreach loop?

Jon Skeet
people
quotationmark

It sounds like you want:

var authorize = user.RolesList.Exists(r => allowedRoles.Contains(r.Name));

Or transform the list of roles into their names, and see whether that intersects with the allowed roles:

var authorize = user.RolesList.Select(r => r.Name).Intersect(allowedRoles).Any();

Note that you could use Any instead of Exists, which would stop it being specific to List<T>:

var authorize = user.RolesList.Any(r => allowedRoles.Contains(r.Name));

Also note that even though the foreach loop is no longer in the code, using LINQ won't make this code any faster - there's still a loop, it's just in the LINQ code rather than in your code. But hey, readability is still a big win :)

people

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