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dotnet xml : XPath question
<authors> <author> <name>Mike Galos</name> <nationality>French</nationality> </author> <author period="modern"> <name>Eva Corets</name> <nationality>British</nationality> </author> <author> <name>Cynthia Randall</name> <nationality>Canadian</nationality> </author> <author> <name>Stefan Knorr</name> <nationality>Canadian</nationality> </author> <author period="modern"> <name>Paula Thurman</name> <nationality>British</nationality> </author> </authors> I want to use an XPath expression to select all Canadian authors, but want the results to be nested within their ancestor like so: <authors> <author> <name>Cynthia Randall</name> <nationality>Canadian</nationality> </author> <author> <name>Stefan Knorr</name> <nationality>Canadian</nationality> </author> </authors> Is this possible with XPath? If I use /authors/author[nationality='Canadian']/ancestor-or-self::* as my XPath expression, I get back the root node and all it's
XPath won't give you what you want.
-Naraen ------ [quoted text, click to view] "Brad" <veloearl@hotmail.com> wrote in message news:923c671f.0403310638.33f41a2e@posting.google.com... > Let's say I have the following XML: > > <authors> > <author> > <name>Mike Galos</name> > <nationality>French</nationality> > </author> > <author period="modern"> > <name>Eva Corets</name> > <nationality>British</nationality> > </author> > <author> > <name>Cynthia Randall</name> > <nationality>Canadian</nationality> > </author> > <author> > <name>Stefan Knorr</name> > <nationality>Canadian</nationality> > </author> > <author period="modern"> > <name>Paula Thurman</name> > <nationality>British</nationality> > </author> > </authors> > > I want to use an XPath expression to select all Canadian authors, but > want the results to be nested within their ancestor like so: > > <authors> > <author> > <name>Cynthia Randall</name> > <nationality>Canadian</nationality> > </author> > <author> > <name>Stefan Knorr</name> > <nationality>Canadian</nationality> > </author> > </authors> > > Is this possible with XPath? If I use > > /authors/author[nationality='Canadian']/ancestor-or-self::* > > as my XPath expression, I get back the root node and all it's > descendants, which is not what I want.
Brad,
XPath will allow you to specify which nodes in your input document you want to select. XPath statements will return a list of nodes that match your statement. XPath itself won't transform your XML into another format. If what you're trying to do is generate an output document that has a different format from the input document then perhaps XSLT is what you're really after. XSLT will allow you to transform an input XML document into an output XML document, and as part of that transform you will specify an XPath to tell the transform which parts of the input document you'd like tranformed (e.g. "transform all of the Canadian authors only"). http://www.xml.com/pub/a/2000/08/holman/index.html give a good write-up of XSLT. There are other ways of generating your output XML (using a DOM, using custom code) but they really depend upon what you're doing. For example, if you're dealing with XML files, if you're dealing with XML that's already been loaded into a DOM, if you're dealing with XML that's part of a stream. Regards, Martin -- This posting is provided "AS IS" with no warranties, and confers no rights. [quoted text, click to view] "Brad" <veloearl@hotmail.com> wrote in message news:923c671f.0403310638.33f41a2e@posting.google.com... > Let's say I have the following XML: > > <authors> > <author> > <name>Mike Galos</name> > <nationality>French</nationality> > </author> > <author period="modern"> > <name>Eva Corets</name> > <nationality>British</nationality> > </author> > <author> > <name>Cynthia Randall</name> > <nationality>Canadian</nationality> > </author> > <author> > <name>Stefan Knorr</name> > <nationality>Canadian</nationality> > </author> > <author period="modern"> > <name>Paula Thurman</name> > <nationality>British</nationality> > </author> > </authors> > > I want to use an XPath expression to select all Canadian authors, but > want the results to be nested within their ancestor like so: > > <authors> > <author> > <name>Cynthia Randall</name> > <nationality>Canadian</nationality> > </author> > <author> > <name>Stefan Knorr</name> > <nationality>Canadian</nationality> > </author> > </authors> > > Is this possible with XPath? If I use > > /authors/author[nationality='Canadian']/ancestor-or-self::* > > as my XPath expression, I get back the root node and all it's > descendants, which is not what I want.
You can use the following code:
XPathNodeIterator it = nav.Select("/authors/author[nationality='Canadian']"); XPathIteratorReader reader = new XPathIteratorReader(it, "authors"); reader.MoveToContent(); string xml = reader.ReadOuterXml(); // now xml contains the format you wanted. // To save the subset to file XmlTextWriter tw = new XmlTextWriter(destination); tw.WriteNode( new XPathIteratorReader( it, "authors" ) ); tw.Close(); The XPathIteratorReader implements IXmlSerializable, so you can also return it directly from a webservice. Check it out at http://weblogs.asp.net/cazzu/archive/2004/04/26/120684.aspx -- Daniel Cazzulino [MVP XML] Clarius Consulting SA http://weblogs.asp.net/cazzu http://aspnet2.com [quoted text, click to view] "Martin Peck [MSFT]" <mpeck@online.microsoft.com> wrote in message news:##Lvj1IHEHA.956@TK2MSFTNGP09.phx.gbl... > Brad, > > XPath will allow you to specify which nodes in your input document you want > to select. XPath statements will return a list of nodes that match your > statement. XPath itself won't transform your XML into another format. > > If what you're trying to do is generate an output document that has a > different format from the input document then perhaps XSLT is what you're > really after. XSLT will allow you to transform an input XML document into an > output XML document, and as part of that transform you will specify an XPath > to tell the transform which parts of the input document you'd like > tranformed (e.g. "transform all of the Canadian authors only"). > > http://www.xml.com/pub/a/2000/08/holman/index.html give a good write-up of > XSLT. > > There are other ways of generating your output XML (using a DOM, using > custom code) but they really depend upon what you're doing. For example, if > you're dealing with XML files, if you're dealing with XML that's already > been loaded into a DOM, if you're dealing with XML that's part of a stream. > > Regards, > > Martin > > -- > This posting is provided "AS IS" with no warranties, and confers no > rights. > > > "Brad" <veloearl@hotmail.com> wrote in message > news:923c671f.0403310638.33f41a2e@posting.google.com... > > Let's say I have the following XML: > > > > <authors> > > <author> > > <name>Mike Galos</name> > > <nationality>French</nationality> > > </author> > > <author period="modern"> > > <name>Eva Corets</name> > > <nationality>British</nationality> > > </author> > > <author> > > <name>Cynthia Randall</name> > > <nationality>Canadian</nationality> > > </author> > > <author> > > <name>Stefan Knorr</name> > > <nationality>Canadian</nationality> > > </author> > > <author period="modern"> > > <name>Paula Thurman</name> > > <nationality>British</nationality> > > </author> > > </authors> > > > > I want to use an XPath expression to select all Canadian authors, but > > want the results to be nested within their ancestor like so: > > > > <authors> > > <author> > > <name>Cynthia Randall</name> > > <nationality>Canadian</nationality> > > </author> > > <author> > > <name>Stefan Knorr</name> > > <nationality>Canadian</nationality> > > </author> > > </authors> > > > > Is this possible with XPath? If I use > > > > /authors/author[nationality='Canadian']/ancestor-or-self::* > > > > as my XPath expression, I get back the root node and all it's > > descendants, which is not what I want. > > --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.665 / Virus Database: 428 - Release Date: 23/04/2004
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