matlab.io.xml.xpath.EvalResultType Class

Namespace: matlab.io.xml.xpath

Result type for XPath expression evaluation

Since R2021a

Description

The matlab.io.xml.xpath.EvalResultType class enumerates the types of values that an XPath expression evaluation can return. To specify a result type for an evaluation, provide the enumeration member as the last argument of the evaluate method of a matlab.io.xml.xpath.Evaluator object.

Enumeration Member	Returns
matlab.io.xml.xpath.EvalResultType.Node	The first node selected by the XPath expression as a matlab.io.xml.dom node object, such as a matlab.io.xml.dom.Element object.
matlab.io.xml.xpath.EvalResultType.NodeSet	The nodes selected by the XPath expression as a vector of matlab.io.xml.dom node objects.
matlab.io.xml.xpath.EvalResultType.Number	The value of the first node selected by the XPath expression as a double.
matlab.io.xml.xpath.EvalResultType.Boolean	The value of the first node selected by the XPath expression as a logical.
matlab.io.xml.xpath.EvalResultType.String	The value of the first node selected by the XPath expression as a string scalar.

Examples

Evaluate an XPath Expression in the Context of an XML File

This example evaluates an XPath expression that finds the nodes with the name Instrument in the file music.xml.

The file music.xml contains this XML markup:

<MusicalEnsemble>
	<Ensemble>
		<Music>Jazz</Music>
            <BandName>Kool Katz</BandName>
		<Instrumentation>
			<Instrument type="wind">Trumpet
            </Instrument>
			<Instrument type="percussion">Piano
                <pianotype>concert grand</pianotype>
            </Instrument>
			<Instrument type="percussion">Drums
                <drumkit>Bass drum</drumkit>
                <drumkit>Floor tom</drumkit>
                <drumkit>Snare drum</drumkit>
                <drumkit>Hi-hat</drumkit>
                <drumkit>Ride cymbal</drumkit>
            </Instrument>
			<Instrument type="string">Bass
                <basstype>upright</basstype>
            </Instrument>
		</Instrumentation>
	</Ensemble>
    <Musicians>
        <Name role="trumpeter">Miles</Name>
        <Name role="vocalist">Roger</Name>
        <Name role="pianist">Diana</Name>
        <Name role="drummer">George</Name>
        <Name role="bassist">John</Name>
    </Musicians>
</MusicalEnsemble>

Define the XPath expression and specify the XML file.

import matlab.io.xml.xpath.*

xpExpr = "//Instrument";
xmlFilePath = "music.xml";

Evaluate the XPath expression and return the nodes as a vector of node objects.

data = evaluate(Evaluator,xpExpr,xmlFilePath,EvalResultType.NodeSet)

data=1×4 Element array with properties:
    TagName
    HasAttributes
    TextContent
    Children

Version History

Introduced in R2021a