Custom XML Serialization and handling CDATA

Question

I have a custom XML Serializer as follows

    public void WriteXml(XmlWriter writer)
    {
        foreach (PropertyInfo pi in this.GetType().GetProperties())
        {
            if (pi.GetCustomAttributes(typeof(XmlIgnoreAttribute), true).Count() == 0)
            {
                var attrList = pi.GetCustomAttributes(typeof(XmlElementAttribute), true);

                if (attrList.Count() > 0)
                {
                    XmlElementAttribute xe = (XmlElementAttribute)attrList[0];
                    writer.WriteStartElement(xe.ElementName);
                }
                else
                {
                    writer.WriteStartElement(pi.Name);
                }

                if (pi.PropertyType == typeof(int) || (pi.PropertyType == typeof(float)))
                {
                    writer.WriteString(pi.GetValue(this, null).ToString());
                }
                else if (pi.PropertyType == typeof(DateTime))
                {
                    DateTime dt = (DateTime)(pi.GetValue(this, null));

                    writer.WriteString(dt.ToString("yyyyMMddHHmm"));
                }
                else
                {

                    if (pi.GetValue(this, null) == null) writer.WriteString(String.Empty);
                    else
                    {
                        // write code to generate CDATA 

                        String val = pi.GetValue(this, null).ToString();

                        if (val.IndexOfAny(invalidChars) != -1)
                            writer.WriteString(String.Format(@"<![CDATA[{0}]]>", pi.GetValue(this, null).ToString()));
                        else writer.WriteString(pi.GetValue(this, null).ToString());
                    }

                }

                writer.WriteEndElement();
            }


        }
    }
}

}

The problem arises when the value contains one of the characters which is invalid in an XML Value. This is detected successfully with these lines

                    if (val.IndexOfAny(invalidChars) != -1)
                        writer.WriteString(String.Format(@"<![CDATA[{0}]]>", pi.GetValue(this, null).ToString()));
                    else writer.WriteString(pi.GetValue(this, null).ToString());

The problem is the creation of the CDATA - instead of getting a properly formatted CDATA what I am getting is & gt ; and & lt ;

So how should you create a properly formatted CDATA within a custom serializer?

Answer 1

Answer provided by Jeroen Mostert in the comments.

Replace the following code

if (val.IndexOfAny(invalidChars) != -1) writer.WriteString(String.Format(@"<![CDATA[{0}]]>", pi.GetValue(this, null).ToString()));
else writer.WriteString(pi.GetValue(this, null).ToString());

with

if (val.IndexOfAny(invalidChars) != -1) writer.WriteRaw(String.Format(@"<![CDATA[{0}]]>", pi.GetValue(this, null).ToString()));
else writer.WriteString(pi.GetValue(this, null).ToString());

The CDATA is then written to the stream correctly and saved to disk in the correct format.

WriteString has been replaced with WriteRaw.