XML Serialization and namespace prefixes

Question

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?

Plywood

Answer 1

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.

Lith

+1 but could I suggest an edit to make it clear that the first parameter in the .Add method is the place where the magic happens for setting the prefix. It wasn't clear to me from the answer until I checked the MSDN docs. – Mcqueen

fair to assume that there isn't an equivalent with DataContractSerializer? (Just wanting to keep my options open) – Plywood

@Slace - yes, I believe it is safe to assume that there isn't an equivalent for DCS. Ultimately, DCS isn't intended to give you much control over the output (if you want to control the xml, use XmlSerializer - that is its job). – Lith

Is there any way to do this with class attributes like this: [XmlRoot("Node", Namespace="http://flibble", NamespacePrefix="myNamespace")] ? – Helmholtz

@Helmholtz yes, and there is an example on MSDN here: msdn.microsoft.com/en-us/library/dzxwk3ez(v=vs.110).aspx – Lith

Is it possible to add multiple namespaces? – Viaticum

@CiaranGallagher a single element can only be in a single namespace; it can, however, declare any number of namespace aliases, and it can have attributes and elements inside it in any number of namespaces. What scenario do you have in mind where you think multiple namespaces might help? – Lith

Answer 2

When using generated code from a schema where the types have namespaces this namespace override applies at the root level but the tags within of varying types will have the namespace associated with the class.

I had an occasion to need to use two different generated classes but have different name spaces based on which server I was talking to (don't ask not under my control).

I tried all the overrides offered here and finally gave up and used a kind of brute force method that actually worked pretty well. What I did was serialize to a string. Then use string.replace to change the namespaces then posted the stream from the string by using a stringwriter. Same on the response - capture to a string - manipulate the namespace then deserialize the string from a string writer.

It may not be elegant or use all the fancy overrides but it got the job done.

Tudela

I had a similar issue, and my solution was to explicitly assign the "" namespace to all of the properties in the class in the XmlElementAttribute value and then add the override for the parent class only when it was needed. I am working with a 3rd party solution that is out of my control and refuses to change their process because "none of our other clients have this issue" – Idea

Answer 3

I arrived here from another thread that appears "duplicated" but is not in my opinion.

I answered there but is not really legible so let me answer again here.

if your target is to do so something like:

<sample xmlns:sample="urn:sample:ns"> 
    <something>value<something>
    <sample:somethingelse>value2</sample:somethingelse>
    <new_root xmlns:newns="url:new:ns">
        <newns:item1>sample1</newns:item1> 
    </new_root>
</sample>

I did found a solution for you :).

What you need to do is in the "new_root" class add namespace declaration like this.

[XmlNamespaceDeclarations] 
public XmlSerializerNamespaces newns;

and in your item1 classe add the following decoration in order to use your namespace

[XmlElement("item1", Namespace = "url:new:ns")]

Violative

None of this would work on the ROOT node; which coincidentally is what the OP is asking about. – Phototaxis

Hi Christian, yes, as I wrote in my post, I placed my answer here because other thread (which face a different problem, I do agree), is marked as duplicated, sorry if I wasn't clear enough about that, but my aim was to help the people arriving from the other thread, moreover when the OP was already answered. Hope this clarified a little – Effeminacy