diff -r 43e37759235e -r 51a74ef9ed63 Symbian3/SDK/Source/GUID-92C2317A-57B8-558E-984B-B10FD0404981.dita --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/Symbian3/SDK/Source/GUID-92C2317A-57B8-558E-984B-B10FD0404981.dita Wed Mar 31 11:11:55 2010 +0100 @@ -0,0 +1,59 @@ + + + + + +Searching +a DOM Tree using XPathThis topic explains how to search in a DOM tree using an XPath +expression. +

Before you start, you must:

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  • understand XPath syntax and the concept of Document Object Model (DOM).

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  • understand the architecture +and classes of the XML +Engine component.

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  • have created an RXmlEngDocument (called myDoc in this +example), either by parsing an XML file (as indicated in the XML +DOM Parsing Tutorial) or by adding nodes to a new DOM tree.

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 +

XPath is a simple query language for XML. An XPath expression +describes a subset of an XML tree, such as all the elements with a specified +name, or all the children of a specific node. Evaluating an XPath expression +means searching in the XML tree for matching nodes or content: clients of +the XML Engine use it to explore XML data.

The following steps show +how to make an XPath query with the XML Engine.

+ +Create an instance +of RXmlEngXPathExpression by calling the TXmlEngXpathEvaluator::CreateExpressionL() method. +RXmlEngXPathExpression expr = TXmlEngXpathEvaluator::CreateExpressionL( "@*" ); +This XPath expression is only useful to illustrate this tutorial: it +returns all the attributes in an XML tree. + + +Evaluate the XPath expression by applying it to your XML document. +RXmlEngXPathResult searchResult = expr.EvaluateL( myDoc ); +The searchResult variable contains a tree of TXmlEngAttr objects. This tree is a subset of the DOM +tree. + + +Use the result, for example by accessing it as a node set as follows: +RXMLEngNodeSet set = result.AsNodeSet(); +if( for TInt i = 0; i < set.Length(); i++ ) + { + TXmlEngNode resultNode = set[i]; + /* [...] do something with the result */ + } + + +Free your resources as necessary. + + + +Serialising +XML DOM + \ No newline at end of file