XmlWriter encoding UTF-8 using StringWriter in C#

Question

I'm using C# to output an xml file and Im trying to set the xml encoding value to UTF-8 but its currently outputting:

<?xml version="1.0"?>

This is my code:

public sealed class StringWriterWithEncoding: StringWriter {
    private readonly Encoding encoding;

    public StringWriterWithEncoding(Encoding encoding) {
        this.encoding = encoding;
    }

    public override Encoding Encoding {
        get {
            return encoding;
        }
    }
}

private string GetXml(JobStore jobStore) {
    StringWriterWithEncoding sw = new StringWriterWithEncoding();
    XmlWriterSettings settings = new XmlWriterSettings();
    settings.Encoding = Encoding.UTF8;
    settings.Encoding = Encoding.GetEncoding("utf-8");
    settings.Indent = true;
    using(var writer = XmlWriter.Create(sw, settings)) {
        writer.WriteStartDocument();
        writer.WriteStartElement("resources");

        writer.WriteStartElement("string");
        writer.WriteAttributeString("name");
        writer.WriteCData("value");
        writer.WriteEndElement();

        writer.WriteEndElement();
        writer.WriteEndDocument();
    }
    return sw.ToString();
}

Must be something simple I am missing?

Answer 1

Your code does not compile -- StringWriterWithEncoding does not have a parameterless constructor. Or, if it does have a parameterless constructor, maybe it actually looks like this?

public sealed class StringWriterWithEncoding : StringWriter
{
    private readonly Encoding encoding;

    public StringWriterWithEncoding() { }

    public StringWriterWithEncoding(Encoding encoding)
    {
        this.encoding = encoding;
    }

    public override Encoding Encoding
    {
        get { return encoding; }
    }
}

If so, that would explain your problem - the field encoding has been left at its default (null) value, meaning Encoding returns null, and so no encoding will appear in the XML file.

To fix it, eliminate the parameterless constructor, and do:

var sw = new StringWriterWithEncoding(Encoding.UTF8);

Or change the parameterless constructor to explicitly set Encoding.UTF8:

public sealed class StringWriterWithEncoding : StringWriter
{
    private readonly Encoding encoding;

    public StringWriterWithEncoding() : this(Encoding.UTF8) { }

    public StringWriterWithEncoding(Encoding encoding)
    {
        this.encoding = encoding;
    }

    public override Encoding Encoding
    {
        get { return encoding; }
    }
}