Check Properties of a Dynamic Object in .NET

How can you avoid a RuntimeBinderException when working with dynamics?

In JavaScript, checking if an object implements a property is easy; so why can't it be that easy to check dynamics in C#? Well, it sort of is!* If you are using an ExpandoObject, you need only cast it to a Dictionary and check and see if it contains the desired key.

* Offer only valid with ExpandoObject. **
** See sample code for participating interfaces.***
*** Visit your local Visual Studio installation for details.

JavaScript

test("HasProperties", function() {

    var x = { first: "Tom" };

    ok(x.first);

    ok(!x.last);

});

C#

public class ExpandoObjectTests

{

    [Fact]

    public void HasProperties()

    {

        dynamic x = new ExpandoObject();

        x.First = "Tom";

        var map = x as IDictionary<string, object>;

        Assert.True(map.ContainsKey("First"));

        Assert.False(map.ContainsKey("Last"));

    }

}

Enjoy,
Tom