Why is an ExpandoObject breaking code that otherwise works just fine?

Question

Here\'s the setup: I have an Open Source project called Massive and I\'m slinging around dynamics as a way of creating SQL on the fly, and dynamic result sets on the fly.

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Answer 1

It's acting as if you're trying to pass dynamics anonymous types across assemblies, which is not supported. Passing an ExpandoObject is supported though. The work-around I have used, when I need to pass across assemblies, and I have tested it successfully, is to cast the dynamic input variable as an ExpandoObject when you pass it in:

public static dynamic DynamicWeirdness()
{
    dynamic ex = new ExpandoObject();
    ex.TableName = "Products";
    using (var conn = OpenConnection()) {
        var cmd = CreateCommand((ExpandoObject)ex);
        cmd.Connection = conn;
    }
    Console.WriteLine("It worked!");
    Console.Read();
    return null;
}

EDIT: As pointed out in the comments, you CAN pass dynamics across assemblies, you CAN'T pass anonymous types across assemblies without first casting them.

The above solution is valid for the same reason as Frank Krueger states above.

When you pass the dynamic to CreateCommand, the compiler is treating its return type as a dynamic that it has to resolve at runtime.