Error using Soap API from script

I currently have a script that I am trying to use to access an api that works fine in my browser (navigate to http://zulutrade.com/TradeHistoryIndividual.aspx?pid=24508 to see it working by viewing the XHR requests in developer tools when you change the number of trades visible in the trade history).

My code is as follows:

function getHistory() {

  var wsdl = SoapService.wsdl("http://zulutrade.com/WebServices/Performance.asmx?WSDL");

  var performanceService = wsdl.getService("PerformanceWebService");

  var param = Xml.element("GetProviderTrades", [
              Xml.attribute("xmlns", "http://zulutrade.com/WebServices/Performance.asmx?WSDL"),
              Xml.element("start",["0"]),
              Xml.element("length",["100"]),
              Xml.element("sortBy",["dc"]),
              Xml.element("sortAscending",[false]),
              Xml.element("providerId",["24508"]),
              Xml.element("currencyIds",["[]"]),
              Xml.element("fromDateStr",["1984-04-24"]),
              Xml.element("toDateStr",["2011-09-10"]),
              Xml.element("validTrades",[true]),
              Xml.element("lotSize",["2"])
            ]);

  var result = performanceService.invokeOperation("GetProviderTrades", [param]);

  Logger.log(result);
}

I have copied the params from the payload data that I see in my browser, but I am getting the following error:

Request failed for http://zulutrade.com/WebServices/Performance.asmx returned code 500. Server response: soap:ServerServer was unable to process request. ---> There was an error generating the XML document. ---> <>f__AnonymousTypee`2[System.Int32,Z.T[]] cannot b开发者_开发知识库e serialized because it does not have a parameterless constructor. (line 21)

Can anyone shed any light on what I am doing wrong? Do I need to supply some kind of header data (maybe a cookie or something)?

Thanks!

The .NET XmlSerializer requires a parameterless constructor for any type that you ask it to serialize/deserialize so you get this kind of error if you use a C# class that has no default constructor as a parameter or return value for a .asmx Web Service. So it looks as though there could be a problem in the Web service code rather than your JavaScript.

However the XML namespace for the GetProviderTrades element looks wrong to me (given http://zulutrade.com/WebServices/Performance.asmx?op=GetProviderTrades), try replacing the line:

Xml.attribute("xmlns", "http://zulutrade.com/WebServices/Performance.asmx?WSDL"),

with:

Xml.attribute("xmlns", "ZuluTrade.WebServices"),