Question

For brevity’s sake in my code, i’d like to be able to do the following: having a collection, find the first element matching a lambda expression; if it exists, return the value of a property or function. If it doesn’t exist, return null.

Updated examples w. classes

Let’s have a collection of stuff

class Stuff
{
    public int Id { get; set; }
    public string Value { get; set; }
    public DateTime? ExecutionTime { get; set; }
}

What I am aiming for is a way to return nicely when calling this

var list = new Stuff[] { new Stuff() { Id = 1, Value = "label", ExecutionTime = DateTime.Now } };

// would return the value of ExecutionTime for the element in the list
var ExistingTime = list.FirstOrDefault(s => s.Value.Contains("ab")).ExecutionTime;

// would return null
var NotExistingTime = list.FirstOrDefault(s => s.Value.Contains("zzz")).ExecutionTime; 

Is it possible with some linq-syntax-fu or do I have to check explicitly for the return value before proceeding?

Original example w. strings

var stuff = {"I", "am", "many", "strings", "obviously"};

// would return "OBVIOUSLY"
var UpperValueOfAString = stuff.FirstOrDefault(s => s.contains("bvi")).ToUpper();

// would return null
var UpperValueOfAStringWannabe = stuff.FirstOrDefault(s => s.contains("unknown token")).ToUpper();

Comment:
I shouldn’t have used strings in my original example, since it slightly skews the question by centering it on the ToUpper method and the string class. Please consider the updated example

Answer 1

Why not just do:

stuff.Where(s => s.contains("bvi"))
     .Select(s => s.ToUpper())
     .FirstOrDefault()

If you have a “non-default default”, you can do:

stuff.Where(s => s.contains("bvi"))
     .Select(s => s.ToUpper())
     .DefaultIfEmpty("Something Else")
     .First()