C# – How to rename class-names via Xml attributes

cxmlxml-serialization

Suppose I have an XML-serializable class called Song:

[Serializable]
class Song
{
    public string Artist;
    public string SongTitle;
}

In order to save space (and also semi-obfuscate the XML file), I decide to rename the xml elements:

[XmlRoot("g")]
class Song
{
    [XmlElement("a")]
    public string Artist;
    [XmlElement("s")]
    public string SongTitle;
}

This will produce XML output like this:

<Song>
  <a>Britney Spears</a>
  <s>I Did It Again</s>
</Song>

I want to rename/remap the name of the class/object as well. Say, in the above example, I wish to rename the class Song to g. So that the resultant xml should look like this:

<g>
  <a>Britney Spears</a>
  <s>I Did It Again</s>
</g>

Is it possible to rename class-names via xml-attributes?

I don't wish to create/traverse the DOM manually, so I was wondering if it could be achieved via a decorator.

Thanks in advance!

UPDATE: Oops! This time I really did it again!
Forgot to mention – I'm actually serializing a list of Song objects in the XML.

Here's the serialization code:

    public static bool SaveSongs(List<Song> songs)
    {
            XmlSerializer serializer = new XmlSerializer(typeof(List<Song>));
            using (TextWriter textWriter = new StreamWriter("filename"))
            {
                serializer.Serialize(textWriter, songs);
            }
    }

And here's the XML output:

<?xml version="1.0" encoding="utf-8"?>
<ArrayOfSong>
<Song>
  <a>Britney Spears</a>
  <s>Oops! I Did It Again</s>
</Song>
<Song>
  <a>Rihanna</a>
  <s>A Girl Like Me</s>
</Song>
</ArrayOfSong>

Apparently, the XmlRoot() attribute doesn't rename the object in a list context.

Am I missing something?

Best Answer

Solution: Use [XmlType(TypeName="g")]

XmlRoot only works with XML root nodes as per the documentation (and what you would expect, given its name includes root)!

I was unable to get any of the other answers to work so kept digging...

Instead I found that the XmlTypeAttribute (i.e. [XmlType]) and its TypeName property do a similar job for non-root classes/objects.

e.g.

[XmlType(TypeName="g")]
class Song
{
    public string Artist;
    public string SongTitle;
}

Assuming you apply it to the other classes e.g.:

[XmlType(TypeName="a")]
class Artist
{
    .....
}

[XmlType(TypeName="s")]
class SongTitle
{
    .....
}

This will output the following exactly as required in the question:

<g>
  <a>Britney Spears</a>
  <s>I Did It Again</s>
</g>

I have used this in several production projects and found no problems with it.

Related Solutions

C# – How to cast int to enum

From an int:

YourEnum foo = (YourEnum)yourInt;

From a string:

YourEnum foo = (YourEnum) Enum.Parse(typeof(YourEnum), yourString);

// The foo.ToString().Contains(",") check is necessary for enumerations marked with an [Flags] attribute
if (!Enum.IsDefined(typeof(YourEnum), foo) && !foo.ToString().Contains(","))
{
    throw new InvalidOperationException($"{yourString} is not an underlying value of the YourEnum enumeration.")
}

Update:

From number you can also

YourEnum foo = (YourEnum)Enum.ToObject(typeof(YourEnum) , yourInt);

It depends on the scenario. XmlSerializer is certainly one way and has the advantage of mapping directly to an object model. In .NET 3.5, XDocument, etc. are also very friendly. If the size is very large, then XmlWriter is your friend.

For an XDocument example:

Console.WriteLine(
    new XElement("Foo",
        new XAttribute("Bar", "some & value"),
        new XElement("Nested", "data")));

Or the same with XmlDocument:

XmlDocument doc = new XmlDocument();
XmlElement el = (XmlElement)doc.AppendChild(doc.CreateElement("Foo"));
el.SetAttribute("Bar", "some & value");
el.AppendChild(doc.CreateElement("Nested")).InnerText = "data";
Console.WriteLine(doc.OuterXml);

If you are writing a large stream of data, then any of the DOM approaches (such as XmlDocument/XDocument, etc.) will quickly take a lot of memory. So if you are writing a 100 MB XML file from CSV, you might consider XmlWriter; this is more primitive (a write-once firehose), but very efficient (imagine a big loop here):

XmlWriter writer = XmlWriter.Create(Console.Out);
writer.WriteStartElement("Foo");
writer.WriteAttributeString("Bar", "Some & value");
writer.WriteElementString("Nested", "data");
writer.WriteEndElement();

Finally, via XmlSerializer:

[Serializable]
public class Foo
{
    [XmlAttribute]
    public string Bar { get; set; }
    public string Nested { get; set; }
}
...
Foo foo = new Foo
{
    Bar = "some & value",
    Nested = "data"
};
new XmlSerializer(typeof(Foo)).Serialize(Console.Out, foo);

This is a nice model for mapping to classes, etc.; however, it might be overkill if you are doing something simple (or if the desired XML doesn't really have a direct correlation to the object model). Another issue with XmlSerializer is that it doesn't like to serialize immutable types : everything must have a public getter and setter (unless you do it all yourself by implementing IXmlSerializable, in which case you haven't gained much by using XmlSerializer).

Best Answer

Solution: Use [XmlType(TypeName="g")]

Related Solutions

C# – How to cast int to enum

C# – How to build XML in C#

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