CODEWITHSUNDEEP
javaxmlxpathsaxon
Aravind Yarram
Aravind Yarram

Reputation: 80166

How to check if an element exists in the XML using XPath?

Below is my element hierarchy. How to check (using XPath) that AttachedXml element is present under CreditReport of Primary Consumer

<Consumers xmlns="http://xml.mycompany.com/XMLSchema">
       <Consumer subjectIdentifier="Primary">
          <DataSources>
               <Credit>
                   <CreditReport>
                      <AttachedXml><![CDATA[ blah blah]]>

Upvotes: 64

Views: 177730

Answers (6)

Basheer AL-MOMANI
Basheer AL-MOMANI

Reputation: 15327

take look at my example 

<tocheading language="EN"> 
     <subj-group> 
         <subject>Editors Choice</subject> 
         <subject>creative common</subject> 
     </subj-group> 
</tocheading>

now how to check if creative common is exist 

tocheading/subj-group/subject/text() = 'creative common'

hope this help you

Upvotes: -2

x_kiter
x_kiter

Reputation: 23

If boolean() is not available (the tool I'm using does not) one way to achieve it is:

//SELECT[@id='xpto']/OPTION[not(not(@selected))]

In this case, within the /OPTION, one of the options is the selected one. The "selected" does not have a value... it just exists, while the other OPTION do not have "selected". This achieves the objective.

Upvotes: -1

Dimitre Novatchev
Dimitre Novatchev

Reputation: 243459

Use:

boolean(/*/*[@subjectIdentifier="Primary"]/*/*/*/*
                           [name()='AttachedXml' 
                          and 
                            namespace-uri()='http://xml.mycompany.com/XMLSchema'
                           ]
       )

Upvotes: 6

Mads Hansen
Mads Hansen

Reputation: 66714

Use the boolean() XPath function

The boolean function converts its argument to a boolean as follows:

  • a number is true if and only if it is neither positive or negative zero nor NaN

  • a node-set is true if and only if it is non-empty

  • a string is true if and only if its length is non-zero

  • an object of a type other than the four basic types is converted to a boolean in a way that is dependent on that type

If there is an AttachedXml in the CreditReport of primary Consumer, then it will return true().

boolean(/mc:Consumers
          /mc:Consumer[@subjectIdentifier='Primary']
            //mc:CreditReport/mc:AttachedXml)

Upvotes: 98

Jon Gauthier
Jon Gauthier

Reputation: 25572

The Saxon documentation, though a little unclear, seems to suggest that the JAXP XPath API will return false when evaluating an XPath expression if no matching nodes are found.

This IBM article mentions a return value of null when no nodes are matched.

You might need to play around with the return types a bit based on this API, but the basic idea is that you just run a normal XPath and check whether the result is a node / false / null / etc.

XPathFactory xpathFactory = XPathFactory.newInstance(NamespaceConstant.OBJECT_MODEL_SAXON);
XPath xpath = xpathFactory.newXPath();
XPathExpression expr = xpath.compile("/Consumers/Consumer/DataSources/Credit/CreditReport/AttachedXml");
Object result = expr.evaluate(doc, XPathConstants.NODE);

if ( result == null ) {
    // do something
}

Upvotes: 6

Simon Stender Boisen
Simon Stender Boisen

Reputation: 3431

Normally when you try to select a node using xpath your xpath-engine will return null or equivalent if the node doesn't exists. 

xpath: "/Consumers/Consumer/DataSources/Credit/CreditReport/AttachedXml"

If your using xsl check out this question for an answer:

xpath find if node exists

Upvotes: 4

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