Dealing with invalid XML hexadecimal characters

Question

I\'m trying to send an XML document over the wire but receiving the following exception:

\"MY LONG EMAIL STRING\" was specified for the \'Body\' element. ---         


        

Answer 1

There is a generic solution that works nicely:

public class XmlTextTransformWriter : System.Xml.XmlTextWriter
{
    public XmlTextTransformWriter(System.IO.TextWriter w) : base(w) { }
    public XmlTextTransformWriter(string filename, System.Text.Encoding encoding) : base(filename, encoding) { }
    public XmlTextTransformWriter(System.IO.Stream w, System.Text.Encoding encoding) : base(w, encoding) { }

    public Func TextTransform = s => s;

    public override void WriteString(string text)
    {
        base.WriteString(TextTransform(text));
    }

    public override void WriteCData(string text)
    {
        base.WriteCData(TextTransform(text));
    }

    public override void WriteComment(string text)
    {
        base.WriteComment(TextTransform(text));
    }

    public override void WriteRaw(string data)
    {
        base.WriteRaw(TextTransform(data));
    }

    public override void WriteValue(string value)
    {
        base.WriteValue(TextTransform(value));
    }
}

Once this is in place, you can then create your override of THIS as follows:

public class XmlRemoveInvalidCharacterWriter : XmlTextTransformWriter
{
    public XmlRemoveInvalidCharacterWriter(System.IO.TextWriter w) : base(w) { SetTransform(); }
    public XmlRemoveInvalidCharacterWriter(string filename, System.Text.Encoding encoding) : base(filename, encoding) { SetTransform(); }
    public XmlRemoveInvalidCharacterWriter(System.IO.Stream w, System.Text.Encoding encoding) : base(w, encoding) { SetTransform(); }

    void SetTransform()
    {
        TextTransform = XmlUtil.RemoveInvalidXmlChars;
    }
}

where XmlUtil.RemoveInvalidXmlChars is defined as follows:

    public static string RemoveInvalidXmlChars(string content)
    {
        if (content.Any(ch => !System.Xml.XmlConvert.IsXmlChar(ch)))
            return new string(content.Where(ch => System.Xml.XmlConvert.IsXmlChar(ch)).ToArray());
        else
            return content;
    }