Iterating through a Enumerable collection with nullable types

Question

Hey, I'm trying to iterate over an Enumerable collection of mix of nullable types However I want to compare the nullable type with a intrinsic type such as string or decimal. i.e. Here is a snippet

       <% foreach (PropertyInfo prop in this.Columns)
      { %>
        <td>
        <% var typeCode = Type.GetTypeCode(prop.PropertyType); %>


        <%-- String Columns --%>
        <% if (typeCode == TypeCode.String) 
           { %> ....

prop.PropertyType is of type 'datetime?', however var typeCode is 'object'.So when i compare typeCode to TypeCode.String, it fails. Is there a way to resolve a nullable type to it's underlying type? , e.g resolve datetime? to datetime.

Answer 1

You can use the static Nullable.GetUndlerlyingType method. I would probably wrap it in an extension method for ease of use:

public static Type GetUnderlyingType(this Type source)
{
    if (source.IsGenericType
        && (source.GetGenericTypeDefinition() == typeof(Nullable<>)))
    {
        // source is a Nullable type so return its underlying type
        return Nullable.GetUnderlyingType(source);
    }

    // source isn't a Nullable type so just return the original type
    return source;
}

You'll need to change your example code to look something like this:

<% var typeCode = Type.GetTypeCode(prop.PropertyType.GetUnderlyingType()); %>