Using LINQ, is it possible to output a dynamic object from a Select statement? If so, how?

Question

Presently in LINQ, the following compiles and works just fine:

var listOfFoo = myData.Select(x => new FooModel{
     someProperty = x.prop1,
     someOtherProperty = x.prop2
});

public class FooModel{
     public string someProperty  { get; set; };
     public string someOtherProperty  { get; set; };
}

However, the past few versions of .NET/C# have expanded the role of dynamic objects such as the ExpandoObject and I am wondering if there is a way to basically do this:

var listOfFoo = myData.Select(x => new ExpandoObject{
     someProperty = x.prop1,
     someOtherProperty = x.prop2
});

Obviously, I have already tried the code above without success, but it seems like I am missing something.

Answer 1

You should be able to create a new anonymous object without any type declared:

var listOfFoo = myData.Select(x => new {
    someProperty = x.prop1,
    someOtherProperty = x.prop2
});

Answer 2

There is nothing preventing you from using Select to return a collection of ExpandoObject's, you just aren't properly constructing the ExpandoObject. Here's one way:

var listOfFoo = myData.Select(x =>
    {
        dynamic expando = new ExpandoObject();
        expando.someProperty = x.prop1;
        expando.someOtherProperty = x.prop2;
        return (ExpandoObject)expando;
    });

Answer 3

using (var command = this._context.Database.GetDbConnection().CreateCommand())
        {
            command.CommandText = "select * from persons";
            command.CommandType = CommandType.Text;
            this._context.Database.OpenConnection();
            using (var result = command.ExecuteReader())
            {
                var lst = new List<object>();
                var lstColumns = new UserAccount().GetType().GetProperties(BindingFlags.DeclaredOnly | BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic).ToList();
                while (result.Read())
                {
                    var newObject = new object();
                    dynamic myobject = new ExpandoObject();
                    IDictionary<string, object> myUnderlyingObject = myobject;
                    for (var i = 0; i < result.FieldCount; i++)
                    {
                        var name = result.GetName(i);
                        var val = result.IsDBNull(i) ? null : result[i];
                        myUnderlyingObject.Add(name, val);
                    }
                    lst.Add(myUnderlyingObject);
                }
                return Ok(lst);
            }
        }