Make dictionary read only in C#

Question

I have a Dictionary> and would like to expose the member as read only. I see that I can return it as a IReadOnlyDictionar

Answer 1

It would be as easy as casting the whole dictionary reference to IReadOnlyDictionary> because Dictionary implements IReadOnlyDictionary.

BTW, you can't do that because you want the List values as IReadOnlyList.

So you need something like this:

var readOnlyDict = (IReadOnlyDictionary>)dict.ToDictionary(pair => pair.Key, pair => pair.Value.AsReadOnly());

Immutable dictionaries

This is just a suggestion, but if you're looking for immutable dictionaries, add System.Collections.Immutable NuGet package to your solution and you'll be able to use them:

// ImmutableDictionary>
var immutableDict = dict.ToImmutableDictionary(pair => pair.Key, pair => pair.Value.ToImmutableList());

Learn more about Immutable Collections here.