Writing XML Elements

Now that the XML declaration is written, it's time to start writing some real XML data. The most important node is the XML element. Elements can be written piece by piece or all at once.

Writing an element piece by piece is necessary when the element needs to contain attributes or child nodes. The XmlTextReader provides WriteStartElement and WriteEndElement to support this functionality. Calling WriteStartElement will write the specified start tag and associate it with an optional namespace and prefix. After the start tag is written, you can then write attributes on the element. You can also write child nodes. But you can no longer write an attribute on an element after a child node has been written.

Listing 10.23 demonstrates how to use WriteElementString and WriteEndElement to write an empty element.

WRITING FULL END ELEMENT TAGS

The XmlTextWriter will write true empty elements whenever you write an element with no content. If this is not the desired behavior, use WriteFullEndElement to make sure both the start tag and the end tag are written to the stream.

 C# // Make a true empty element writer.WriteStartElement("True_Empty"); writer.WriteEndElement(); // Make an empty element with start and end tags writer.WriteStartElement("Empty"); writer.WriteFullEndElement(); VB ' Make a true empty element writer.WriteStartElement("True_Empty") writer.WriteEndElement() ' Make an empty element with start and end tags writer.WriteStartElement("Empty") writer.WriteFullEndElement() Output <True_Empty /> <Empty> </Empty> 

Listing 10.23

 C# XmlTextWriter writer =   new XmlTextWriter("startelem.xml", Encoding.UTF8); writer.Formatting = Formatting.Indented; writer.WriteStartDocument(); writer.WriteStartElement("root"); writer.WriteEndElement(); writer.Close(); VB Dim writer As   New XmlTextWriter("startelem.xml", Encoding.UTF8) writer.Formatting = Formatting.Indented writer.WriteStartDocument() writer.WriteStartElement("root") writer.WriteEndElement() writer.Close() Output <?xml version="1.0" encoding="utf-8"?> <root /> 

An element that contains only text can be written by calling one, single API method, WriteElementString , which will write out the start tag, the text content, and the end tag. Unfortunately, attributes other than namespace declarations cannot be written. Listing 10.24 demonstrates how to use WriteElementString .

Listing 10.24

 C# XmlTextWriter writer =   new XmlTextWriter("elementstring.xml", Encoding.UTF8); writer.Formatting = Formatting.Indented; writer.WriteStartElement("StockQuote", "http://fakequote.com"); writer.WriteElementString   ("Symbol", "http://fakequote.com", "MSFT"); writer.WriteElementString("Value",                           "http://fakequote.com",                           XmlConvert.ToString(123.32)); writer.WriteEndElement(); writer.Close(); VB Dim writer As   New XmlTextWriter("elementstring.xml", Encoding.UTF8) writer.Formatting = Formatting.Indented writer.WriteStartElement("StockQuote", "http://fakequote.com") writer.WriteElementString _   ("Symbol", "http://fakequote.com", "MSFT") writer.WriteElementString("Value", _                           "http://fakequote.com", _                           XmlConvert.ToString(123.32)) writer.WriteEndElement() writer.Close() Output <StockQuote xmlns="http://fakequote.com">   <Symbol>MSFT</Symbol>   <Value>123.32</Value> </StockQuote>