Pass null value to ASP.NET web service using HTTP POST?

How do I pass a null value to an ASP.NET web service when accessing it via 开发者_如何学JAVAHTTP POST?

[WebMethod]
public string GetResult(DateTime date, int foo)
{
  //do stuff here
}

When calling this method using HTTP POST, how do I pass a null parameter? Passing empty string just makes the server throw an exception trying to convert the string parameter to a DateTime. Making the DateTime parameter nullable (i.e. DateTime? date) seems to disallow calling it via HTTP.

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Neither of these can have null values. They are both value types and can't be set to null even if you attempted to do it using code. I would recommend sending DateTime.MinValue and 0.