Serialize String containing only whitespace such as a " " character

Question

I'm having dufficulty figuring out how to serialize a String property
[XmlElement("DescriptionDelimiter1")]
public String DescriptionDelimiter1
    get { return _DescriptionDelimiter1; }
    set { _DescriptionDelimiter1 = value; }
Granted, I don't really need the XmlElement tag but just in case I want to change the name of the XML element...
Anyway, what I get in XML is
<ImportProfiles>
  <ImportProfile Name="HPH Import Profile">
    <ConcatenateDescriptions>true</ConcatenateDescriptions>
    <DescriptionDelimiter1 />
    <DescriptionDelimiter2>\r\n</DescriptionDelimiter2>
    <DescriptionDelimiter3>\t</DescriptionDelimiter3>
  <ImportProfile>
</ImportProfiles>
The problem is when serialized, if the value is " " or a single space, the result is <DescriptionDelimiter1 /> which when deserialized sets the string's value to "" with is not the value I need. I've looked into using CData but there doesn't seem to be a simple way to implement it... I expect
<DescriptionDelimiter1> </DescriptionDelimiter1>
or
<DescriptionDelimiter1><[CDATA[ ]]></DescriptionDelimiter1>
Is there some setting I can use when serializing the object to indication the process should not trim away whitespace?
The following is the method used to serialize my object:
public static String Serialize(DataImportBase dib)
    System.Type[] ArrType = new Type[1];
    ArrType[0] = typeof(System.DBNull);
    XmlSerializer xs = new XmlSerializer(typeof(DataImportBase), ArrType);
    System.IO.MemoryStream aMemoryStream = new System.IO.MemoryStream();
    xs.Serialize(aMemoryStream, dib);
    return System.Text.Encoding.UTF8.GetString(aMemoryStream.ToArray());
Thanks for any assistance!!!
Chris

Answer 1

I have looked through the classes for XML serialization but I haven't found anything that seems to allow one to set that attribute xml:space declaratively on members.
One way to change the serialization behaviour would be to write a specialized XmlWriter that takes a list of element names for which it writes out the xml:space attribute. This can be done with a few lines if you use the XmlWrappingWriter from the project http://www.codeplex.com/Wiki/View.aspx?ProjectName=MVPXML. The code for XmlWrappingWriter is also shown in Oleg's blog.
If you use that then you can set up a specialized XmlWriter as follows:
public class XmlSpaceWriter : XmlWrappingWriter
private XmlQualifiedName[] ElementNames;
public XmlSpaceWriter(TextWriter output, XmlQualifiedName[] elementNames)
: base(XmlWriter.Create(output))
ElementNames = elementNames;
public override void WriteStartElement(string prefix, string localName, string ns)
base.WriteStartElement(prefix, localName, ns);
foreach (XmlQualifiedName name in ElementNames)
if (name.Namespace == ns && name.Name == localName && base.XmlSpace != XmlSpace.Preserve)
base.WriteAttributeString("xml", "space", "http://www.w3.org/XML/1998/namespace", "preserve");
break;
and use it like this
Foo foo = new Foo();
foo.Bar = " ";
foo.Example = " ";
XmlSerializer serializer = new XmlSerializer(typeof(Foo));
StringWriter stringWriter = new StringWriter();
XmlSpaceWriter spaceWriter = new XmlSpaceWriter(stringWriter, new XmlQualifiedName[] {new XmlQualifiedName("Bar")});
serializer.Serialize(spaceWriter, foo);
spaceWriter.Close();
string markup = stringWriter.ToString();
The result then looks like this:
<?xml version="1.0" encoding="utf-16"?><Foo xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"><Bar xml:space="preserve"> </Bar><Example> </Example></Foo>
The example code above has just one constructor for a TextWriter but the code could obviously easily extended to have further constructors taking e.g. a stream.