xpath_getelembyattr.html
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<TITLE>Finding Elements by Attributes in a DOM Document Using XPath
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<h3>
e552.
Finding Elements by Attributes in a DOM Document Using XPath</h3>
XPath is an expression language for selecting nodes in an XML file.
See <a href="../org.w3c.dom/xpath_GetAbsElem.html" class="eglink"><font size="-1"><b>e548</b> Finding Elements by Absolute Location in a DOM Document Using XPath</font></a> for common XPath
expression for selecting elements. This example adds to those
examples by demonstrating the ability to select elements based on their
attributes.
<P> This example demonstrates some common uses of expressions that
use attributes; for more information on XPath, see the
specification at <a href="http://www.w3c.org/TR/xpath"><font size="-1">http://www.w3c.org/TR/xpath</font></a>. In the example,
the result of an XPath expression is shown next to the expression; the
numbers are ids of elements in the sample file shown at the end of the
example.
<pre>
// Get all elements where pet equals cat
String xpath = "//*[@pet='cat']"; // 2
// Get all elements where pet equals dog
xpath = "//*[@pet='dog']"; // 7
// Note that element #3 does not match because the attribute
// value is <code>" dog "</code> rather than <code>"dog"</code>
// Get all elements where pet contains the string dog
xpath = "//*[contains(@pet,'dog')]"; // 3 7
// Get all elements that have the age attribute
xpath = "//*[@age]"; // 3 6
// Get all elem1 elements that have the age attribute
xpath = "//elem1[@age]"; // 3
// Get all elements that have both pet and age attributes
xpath = "//*[@pet and @age]"; // 1 3
</pre>
XPath 1.0 does not support case-insensitive matches. However,
a simple case-insensitive match can be done using the <code>translate()</code>
function, which converts a string by mapping one character into another:
<pre>
// Get all elements where pet contains the string cat, ignoring case
xpath = "//*[contains(translate(@pet,'abcdefghijklmnopqrstuvwxyz',"
+ " 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'),'CAT')]"; // 2 4
</pre>
To execute an XPath expression, see
<a href="../org.w3c.dom/xpath_GetAbsElem.html" class="eglink"><font size="-1"><b>e548</b> Finding Elements by Absolute Location in a DOM Document Using XPath</font></a>. Here is the sample XML file
used in the example:
<pre>
<?xml version="1.0" encoding="UTF-8"?>
<root id="1">
<elem1 id="2" pet="cat"/>
<elem1 id="3" pet=" dog " age="8"/>
<elem1 id="4" pet="Cat" >
<elem2 id="5">
<elem3 id="6" age="10"/>
</elem2>
</elem1>
<elem1 id="7" pet="dog"/>
</root>
</pre>
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Related Examples
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e548. <a class="eglink" href="xpath_GetAbsElem.html?l=rel">
Finding Elements by Absolute Location in a DOM Document Using XPath
</a>
<br>
e549. <a class="eglink" href="xpath_GetChildElem.html?l=rel">
Selecting from a Set of Child Elements in a DOM Document Using XPath
</a>
<br>
e550. <a class="eglink" href="xpath_GetElemByText.html?l=rel">
Finding Elements by Content in a DOM Document Using XPath
</a>
<br>
e551. <a class="eglink" href="xpath_GetElemById.html?l=rel">
Finding Elements by Id in a DOM Document Using XPath
</a>
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See also:
<a class="eglink" href="/egs/org.w3c.dom/pkg.html?l=rel#Adding%20and%20Removing%20Nodes">
Adding and Removing Nodes
</a>
<a class="eglink" href="/egs/org.w3c.dom/pkg.html?l=rel#Element%20Attributes">
Element Attributes
</a>
<a class="eglink" href="/egs/org.w3c.dom/pkg.html?l=rel#Elements">
Elements
</a>
<a class="eglink" href="/egs/org.w3c.dom/pkg.html?l=rel#Getting%20Nodes">
Getting Nodes
</a>
<a class="eglink" href="/egs/org.w3c.dom/pkg.html?l=rel#Text%20Nodes">
Text Nodes
</a>
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