DataContractSerializer with Multiple Namespaces

Question

I am using a DataContractSerializer to serialize an object to XML. The main object is SecurityHolding with the namespace "http://personaltrading.test.com/" and contains a property called Amount that's a class with the namespace "http://core.test.com". When I serialize this to XML I get the following:

<ArrayOfSecurityHolding xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://personaltrading.test.com/">
  <SecurityHolding>
    <Amount xmlns:d3p1="http://core.test.com/">
        <d3p1:Amount>1.05</d3p1:Amount>
        <d3p1:CurrencyCode>USD</d3p1:CurrencyCode>
    </Amount>
    <BrokerageID>0</BrokerageID>
    <BrokerageName i:nil="true" />
    <RecordID>3681</RecordID>
  </SecurityHolding></ArrayOfSecurityHolding>

Is there anyway I can control the d3p1 prefix? Am I doing something wrong or should I be doing something else?

Answer 1

Firstly, the choice of namespace alias should make no difference to a well-formed parser.

But; does it have to be DataContractSerializer? With XmlSerializer, you can use the overload of Serialize that accepts a XmlSerializerNamespaces. This allows you to pick and choose the namespaces and aliases that you use.

Ultimately; DataContractSerializer is not intended to give full xml control; that isn't its aim. If you want strict xml control, XmlSerializer is a better choice, even if it is older (and has some nuances/foibles of its own).

Full example:

using System;
using System.Xml.Serialization;
public class Amount
{
    public const string CoreNamespace = "http://core.test.com/";
    [XmlElement("Amount", Namespace=CoreNamespace)]
    public decimal Value { get; set; }
    [XmlElement("CurrencyCode", Namespace = CoreNamespace)]
    public string Currency { get; set; }
}
[XmlType("SecurityHolding", Namespace = SecurityHolding.TradingNamespace)]
public class SecurityHolding
{
    public const string TradingNamespace = "http://personaltrading.test.com/";

    [XmlElement("Amount", Namespace = Amount.CoreNamespace)]
    public Amount Amount { get; set; }

    public int BrokerageId { get; set; }
    public string BrokerageName { get; set; }
    public int RecordId { get; set; }
}
static class Program
{
    static void Main()
    {
        var data = new[] {
            new SecurityHolding {
                Amount = new Amount {
                    Value = 1.05M,
                    Currency = "USD"
                },
                BrokerageId = 0,
                BrokerageName = null,
                RecordId = 3681
            }
        };
        var ser = new XmlSerializer(data.GetType(),
            new XmlRootAttribute("ArrayOfSecurityHolding") { Namespace = SecurityHolding.TradingNamespace});
        var ns = new XmlSerializerNamespaces();
        ns.Add("foo", Amount.CoreNamespace);
        ser.Serialize(Console.Out, data, ns);
    }
}

Output:

<ArrayOfSecurityHolding xmlns:foo="http://core.test.com/" xmlns="http://personaltrading.test.com/">
  <SecurityHolding>
    <foo:Amount>
      <foo:Amount>1.05</foo:Amount>
      <foo:CurrencyCode>USD</foo:CurrencyCode>
    </foo:Amount>
    <BrokerageId>0</BrokerageId>
    <RecordId>3681</RecordId>
  </SecurityHolding>
</ArrayOfSecurityHolding>