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Working with C# Anonymous Types

Asked 2010-10-14T17:14:52.020
27

I am calling a method that returns a List variable that contains a c# Anonymous Type objects. For example:

List<object> list = new List<object>();
foreach ( Contact c in allContacts ) {
    list.Add( new {
        ContactID = c.ContactID,
        FullName = c.FullName
    });
}
return list;

How do I reference this type properties in the code I am working on like for example

foreach ( object o in list ) {
    Console.WriteLine( o.ContactID );
}

I know that my sample is not possible, I have only wrote that way to say that I need to identify each property of the anonymous type exactly.

Thanks!

Solution:

Not just one of the answer is correct and/or suggest a working solution. I have ended up to using Option 3 of Greg answer. And I learned something very interesting regarding the dynamic in .NET 4.0!

c# dynamic .net-4.0 anonymous-types
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1 Answer

4
foreach ( var o in list ) {
    Console.WriteLine( o.ContactID );
}

this will work only if list is IEnumerable<anonymous type>, like this:

var list = allContacts.Select(c => new {
        ContactID = c.ContactID,
        FullName = c.FullName
    });
}

but you can't return anonymous types, because you must define return type (you can't return var) and anonymous types can't have names. you should create non-anonymous type if you with to pass it. Actually anonymous types should not be used too much, except for inside of queries.

answered 2010-10-14T17:16:47.063

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