C# XmlSerializer Force Encoding Type to ISO-8859-1

Question

I am trying to set encoding type to ISO-8859-1 while serializing an object. The code runs without throwing any exception but the returned coding type is always set to "UTF-16". I have searched many examples, there are 100s of samples, but I am simply unable to force the desired encoding type.

My questions is that how can I force it to set encoding to ISO-8859-1?

Thanks in advance.

The code is:

XmlWriterSettings xmlWriterSettings = new XmlWriterSettings
{
    Indent = true,
    OmitXmlDeclaration = false,
    Encoding = Encoding.GetEncoding("ISO-8859-1")
};

using (var stringWriter = new StringWriter())
{
    using (var xmlWriter = XmlWriter.Create(stringWriter, xmlWriterSettings))
    {
        serializer.Serialize(xmlWriter, obj, ns);
    }

    return stringWriter.ToString();
}

Answer 1

When you write XML to a TextWriter (e.g. StringWriter, StreamWriter), it always uses the encoding specified by the TextWriter, and ignores the one specified in XmlWriterSettings. For StringWriter, the encoding is always UTF-16, because that's the encoding used by .NET strings in memory.

The workaround is to write to a MemoryStream and read the string from there:

var encoding = Encoding.GetEncoding("ISO-8859-1");
XmlWriterSettings xmlWriterSettings = new XmlWriterSettings
{
    Indent = true,
    OmitXmlDeclaration = false,
    Encoding = encoding
};

using (var stream = new MemoryStream())
{
    using (var xmlWriter = XmlWriter.Create(stream, xmlWriterSettings))
    {
        serializer.Serialize(xmlWriter, obj, ns);
    }
    return encoding.GetString(stream.ToArray());
}

Note that if you have the XML in a string, when you write it to a file you need to make sure to write it with the same encoding.