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C# Dynamic select List of strings

Tags:

c#

.net

dynamic

I'm trying to get List of strings from my dynamic object list and it keeps saying that:

Error 1 Cannot implicitly convert type 'System.Collections.Generic.List<dynamic>' to 'System.Collections.Generic.List<string>'

I'm selecting a property and use .ToString() on it:

var objects = new List<dynamic>();
//filling objects here

List<string> things = objects.Select(x => x.nameref.ToString()).ToList();

So isn't it a valid List of strings? Why compiler is assuming that this list is of type dynamic?

I've tried also converting from this answer, but it keeps giving me same error.

Anyone knows how to make it List<string>?

EDIT:

Why isn't it working? Because you can make mess like this:

public class Test
{
    public int ToString()
    {
        return 0;
    }
}

and compiler won't know if ToString returns string or int.

like image 372
Kamil Budziewski Avatar asked Dec 09 '15 07:12

Kamil Budziewski


Video Answer


1 Answers

You need to cast the items, like so:

List<string> things = objects.Select(x => x.nameref.ToString()).Cast<string>().ToList();

The reason why it's not recognizing that ToString() returns a string is that it's called on a dynamic object, and the method binding is done at runtime, not compile time.

like image 77
Rob Avatar answered Sep 28 '22 03:09

Rob