Iterating over a Generic Dictionary

It can be tedious to iterate over a generic Dictionary in C#, especially if the Dictionary contains complex types. The values you’re interested in are properties of the iteration variable. I never know what to name the iteration variable (here I name it “pair”), which is an indicator this code is clumsy.

	private void IterateOverDictionary()
	{
	Dictionary<string, HashSet<string>> claims = GetClaims();
	foreach (KeyValuePair<string, HashSet<string>> pair in claims)
	{
	string claimType = pair.Key;
	HashSet<string> claimValues = pair.Value;
	foreach (string claimValue in claimValues)
	{
	Console.WriteLine($"{claimType} = {claimValue}.");
	}
	}
	}

view raw IterateOverDictionary.cs hosted with by GitHub

Make it easier on yourself by using C#’s Tuple Deconstruction language feature. First, write an extension method for the generic KeyValuePair class.

	public static class ExtensionMethods
	{
	public static void Deconstruct<T1, T2>(this KeyValuePair<T1, T2> Tuple, out T1 Key, out T2 Value)
	{
	Key = Tuple.Key;
	Value = Tuple.Value;
	}
	}

view raw DictionaryTupleDeconstruction.cs hosted with by GitHub

Or, instead of writing the extension method, you can add a reference to my ErikTheCoder.ServiceContract package and add a using ErikTheCoder.ServiceContract; statement.

Then rewrite your foreach loop with more a compact, yet readable, syntax.

	private void IterateOverDictionaryUsingTupleDeconstruction()
	{
	Dictionary<string, HashSet<string>> claims = GetClaims();
	foreach ((string claimType, HashSet<string> claimValues) in claims)
	{
	foreach (string claimValue in claimValues)
	{
	Console.WriteLine($"{claimType} = {claimValue}.");
	}
	}
	}

view raw IterateOverDictionaryTupleDeconstruction.cs hosted with by GitHub