C# – XML Serialization and namespace prefixes

cdatacontractserializerxml-serializationxmlserializer

I'm looking for a way with C# which I can serialize a class into XML and add a namespace, but define the prefix which that namespace will use.

Ultimately I'm trying to generate the following XML:

<myNamespace:Node xmlns:myNamespace="...">
  <childNode>something in here</childNode>
</myNamespace:Node>

I know with both the DataContractSerializer and the XmlSerializer I can add a namespace, but they seem to generate a prefix internally, with something that I'm not able to control. Am I able to control it with either of these serializers (I can use either of them)?

If I'm not able to control the generation of the namespaces will I need to write my own XML serializer, and if so, what's the best one to write it for?

Best Answer

To control the namespace alias, use XmlSerializerNamespaces.

[XmlRoot("Node", Namespace="http://flibble")]
public class MyType {
    [XmlElement("childNode")]
    public string Value { get; set; }
}

static class Program
{
    static void Main()
    {
        XmlSerializerNamespaces ns = new XmlSerializerNamespaces();
        ns.Add("myNamespace", "http://flibble");
        XmlSerializer xser = new XmlSerializer(typeof(MyType));
        xser.Serialize(Console.Out, new MyType(), ns);
    }
}

If you need to change the namespace at runtime, you can additionally use XmlAttributeOverrides.

This is the style that Microsoft tends to use in their examples.

It appears that the guidance in this area may have changed, as StyleCop now enforces the use of the C# specific aliases.

C# – Should ‘using’ directives be inside or outside the namespace

There is actually a (subtle) difference between the two. Imagine you have the following code in File1.cs:

// File1.cs
using System;
namespace Outer.Inner
{
    class Foo
    {
        static void Bar()
        {
            double d = Math.PI;
        }
    }
}

Now imagine that someone adds another file (File2.cs) to the project that looks like this:

// File2.cs
namespace Outer
{
    class Math
    {
    }
}

The compiler searches Outer before looking at those using directives outside the namespace, so it finds Outer.Math instead of System.Math. Unfortunately (or perhaps fortunately?), Outer.Math has no PI member, so File1 is now broken.

This changes if you put the using inside your namespace declaration, as follows:

// File1b.cs
namespace Outer.Inner
{
    using System;
    class Foo
    {
        static void Bar()
        {
            double d = Math.PI;
        }
    }
}

Now the compiler searches System before searching Outer, finds System.Math, and all is well.

Some would argue that Math might be a bad name for a user-defined class, since there's already one in System; the point here is just that there is a difference, and it affects the maintainability of your code.

It's also interesting to note what happens if Foo is in namespace Outer, rather than Outer.Inner. In that case, adding Outer.Math in File2 breaks File1 regardless of where the using goes. This implies that the compiler searches the innermost enclosing namespace before it looks at any using directive.

Best Answer

Related Solutions

C# – the difference between String and string in C#

This is the style that Microsoft tends to use in their examples.

C# – Should ‘using’ directives be inside or outside the namespace

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