As far as XPath/XSLT is concerned, there is no such thing as "an empty text node" -- if it's empty, it's absent. So the Xalan serializer will almost certainly treat empty text nodes as not existing. Any properly written XML application should treat <foo/> and <foo></foo> as IDENTICAL. If you really need to draw this distinction, your output isn't XML.
Maybe your output is HTML. If so, setting the serializer to HTML mode will generate separate start and end tags rather than an empty-element tag. But that has other effects as well, which may or may not be things you want if the document is some SGML language other than HTML. ______________________________________ "... Three things see no end: A loop with exit code done wrong, A semaphore untested, And the change that comes along. ..." -- "Threes" Rev 1.1 - Duane Elms / Leslie Fish ( http://www.ovff.org/pegasus/songs/threes-rev-11.html) Michael Glavassevich <mrgla...@ca.ibm.com> wrote on 12/16/2008 04:23:35 PM: > Michael Glavassevich <mrgla...@ca.ibm.com> > 12/16/2008 04:23 PM > > Please respond to > j-users@xerces.apache.org > > To > > j-users@xerces.apache.org > > cc > > Subject > > Re: How to preserve an empty text node? > > Seems like Xalan has already optimized that. Perhaps if you try a > different serializer (e.g. DOM Level 3 LSSerializer [in > serializer.jar] or Xerces' deprecated one) it will do what you were > hoping for. > > Michael Glavassevich > XML Parser Development > IBM Toronto Lab > E-mail: mrgla...@ca.ibm.com > E-mail: mrgla...@apache.org > > Ian Hummel <hum...@parityinc.net> wrote on 12/15/2008 03:42:50 PM: > > > Hi Michael, > > > > Here is my formatXmlAsString method formatted for brevity: > > > > public static String formatXmlAsString(Document doc) { > > StringWriter out = new StringWriter(); > > TransformerFactory factory = TransformerFactory.newInstance(); > > factory.setAttribute("indent-number", new Integer(2)); > > Transformer serializer; > > serializer = factory.newTransformer(); > > serializer.setOutputProperty(OutputKeys.INDENT, "yes"); > > serializer.setOutputProperty("{http://xml.apache.org/xslt} > > indent-amount", "4"); > > serializer.transform(new DOMSource(doc), new StreamResult(out)); > > return out.toString(); > > } > > > > Here I tried appending a blank text node, and I can see in the DOM > > that the text node _is_ there, but it still gets squashed upon output: > > > > DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); > > DocumentBuilder db = dbf.newDocumentBuilder(); > > Document d = db.newDocument(); > > Element root = d.createElement("root"); > > Element tag = d.createElement("tag"); > > d.appendChild(root); > > root.appendChild(tag); > > > > System.out.println("Child nodes? " + tag.getChildNodes().item(0)); > > System.out.println("Child nodes l? " + tag.getChildNodes().getLength()); > > Text text = d.createTextNode(""); > > tag.appendChild(text); > > System.out.println("Child nodes? " + tag.getChildNodes().item(0)); > > System.out.println("Child nodes l? " + tag.getChildNodes().getLength()); > > System.out.println(formatXmlAsString(d)); > > > > Child nodes? null > > Child nodes l? 0 > > Child nodes? [#text: ] > > Child nodes l? 1 > > <?xml version="1.0" encoding="UTF-8"?> > > <root> > > <tag/> > > </root> > > > > On Dec 15, 2008, at 3:29 PM, Michael Glavassevich wrote: > > > > To add to what I said ... > > > > I think it's likely the case that the Xerces/Xalan serializer will > > write <tag></tag> if you attach an empty text node to the element. > > You should keep in mind that this is an implementation detail that > > could change in the future. Perhaps one day it will write <tag/> instead. > > > > Thanks. > > > > Michael Glavassevich > > XML Parser Development > > IBM Toronto Lab > > E-mail: mrgla...@ca.ibm.com > > E-mail: mrgla...@apache.org > > > > Michael Glavassevich/Toronto/i...@ibmca wrote on 12/15/2008 03:20:57 PM: > > > > > Hi Ian, > > > > > > I've never heard of XmlUtils.formatXmlAsString. It's certainly not > > > distributed with Xerces. Have you tried one of the standard > > > serialization methods [1] from JAXP or DOM Level 3? > > > > > > Thanks. > > > > > > [1] http://xerces.apache.org/xerces2-j/faq-general.html#faq-6 > > > > > > Michael Glavassevich > > > XML Parser Development > > > IBM Toronto Lab > > > E-mail: mrgla...@ca.ibm.com > > > E-mail: mrgla...@apache.org > > > > > > Ian Hummel <hum...@parityinc.net> wrote on 12/15/2008 03:08:49 PM: > > > > > > > Hi Michael, > > > > > > > > I know <tag></tag> and <tag/> are the same, but unfortunately the > > > > buggy-parser-that-cannot-be-changed on the other end doesn't :) > > > > > > > > DocumentBuilder db = dbf.newDocumentBuilder(); > > > > Document d = db.newDocument(); > > > > Element root = d.createElement("root"); > > > > Element tag = d.createElement("tag"); > > > > tag.setTextContent(""); > > > > d.appendChild(root); > > > > root.appendChild(tag); > > > > System.out.println(XmlUtils.formatXmlAsString(d)); > > > > > > > > This always outputs <tag/> and never <tag></tag> like I need it to. > > > > > > > > - Ian. > > > > > > > > On Dec 12, 2008, at 10:33 PM, Michael Glavassevich wrote: > > > > > > > > Hi Ian, > > > > > > > > > I need to create XML that looks like this whenever the value of > > > > > "tag" is "" (the empty string): > > > > > > > > > > <root> > > > > > <tag></tag> > > > > > </root> > > > > > > > > Why? <tag/> and <tag></tag> have the same meaning. Whichever form is > > > > chosen by the serializer should have no significance. > > > > > > > > > I am more concerned in preserving the empty text node when I > > > > > serialize to e.g. a file... not so much the parsing. > > > > > > > > > > Any one else have any ideas? > > > > > > > > Would help if you showed your code for serializing the document. > > > > > > > > > Are blank text nodes like that invalid XML or something? > > > > > > > > In the snippet you posted you created a text node with the '\t' > > > > (tab) character in it. That isn't "blank" or empty. > > > > > > > > Thanks. > > > > > > > > Michael Glavassevich > > > > XML Parser Development > > > > IBM Toronto Lab > > > > E-mail: mrgla...@ca.ibm.com > > > > E-mail: mrgla...@apache.org > > > > > > > > Ian Hummel <hum...@parityinc.net> wrote on 12/12/2008 09:21:47 AM: > > > > > > > > > Hi, I didn't really understand how that's going to help. > > > > > > > > > > I am more concerned in preserving the empty text node when I > > > > > serialize to e.g. a file... not so much the parsing. > > > > > > > > > > Any one else have any ideas? Are blank text nodes like that invalid > > > > > XML or something? > > > > > > > > > > On Dec 11, 2008, at 11:53 AM, ravika...@gmail.com wrote: > > > > > > > > > > Hi Lan, > > > > > > > > > > I think we can Implement by LSParser Interface. http://java.sun. > > > > > com/j2se/1.5.0/docs/api/org/w3c/dom/ls/LSParser.html > > > > > this link may help you. > > > > > > > > > > Regards, > > > > > Ravikanth > > > > > > > > > On Thu, Dec 11, 2008 at 7:36 PM, Ian Hummel <hum...@parityinc.net > > > wrote: > > > > > Hi everyone, > > > > > > > > > > I need to create XML that looks like this whenever the value of > > > > > "tag" is "" (the empty string): > > > > > > > > > > <root> > > > > > <tag></tag> > > > > > </root> > > > > > > > > > > I've tried the following: > > > > > > > > > > DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); > > > > > DocumentBuilder db = dbf.newDocumentBuilder(); > > > > > Document d = db.newDocument(); > > > > > Element root = d.createElement("root"); > > > > > Element tag = d.createElement("tag"); > > > > > d.appendChild(root); > > > > > root.appendChild(tag); > > > > > Text text = d.createTextNode("\t"); > > > > > tag.appendChild(text); > > > > > > > > > > but I always end up with XML like this: > > > > > > > > > > <root> > > > > > <tag/> > > > > > </root> > > > > > > > > > > Is there a way to force empty text nodes to get "denormalized" ? > > > > > > > > > > Thanks, > > > > > > > > > > Ian. > > > > > > > > > > -- > > > > > Ravikanth
