Php – How to use XPath to perform a case-insensitive search and support non-english characters

phpxmlxpath

I am performing a search in an XML file, using the following code:

$result = $xml->xpath("//StopPoint[contains(StopName, '$query')]");

Where $query is the search query, and StopName is the name of a bus stop. The problem is, it's case sensitive.

And not only that, I would also be able to search with non-english characters like ÆØÅæøå to return Norwegian names.

How is this possible?

Best Solution

In XPath 1.0 (which is, I believe, the best you can get with PHP SimpleXML), you'd have to use the translate() function to produce all-lowercase output from mixed-case input.

For convenience, I would wrap it in a function like this:

function findStopPointByName($xml, $query) {
  $upper = "ABCDEFGHIJKLMNOPQRSTUVWXYZÆØÅ"; // add any characters...
  $lower = "abcdefghijklmnopqrstuvwxyzæøå"; // ...that are missing

  $arg_stopname = "translate(StopName, '$upper', '$lower')";
  $arg_query    = "translate('$query', '$upper', '$lower')";

  return $xml->xpath("//StopPoint[contains($arg_stopname, $arg_query)");
}

As a sanitizing measure I would either completely forbid or escape single quotes in $query, because they will break your XPath string if they are ignored.

Related Solutions

Html – How to find an element by CSS class with XPath

This selector should work but will be more efficient if you replace it with your suited markup:

//*[contains(@class, 'Test')]

Or, since we know the sought element is a div:

//div[contains(@class, 'Test')]

But since this will also match cases like class="Testvalue" or class="newTest", @Tomalak's version provided in the comments is better:

//div[contains(concat(' ', @class, ' '), ' Test ')]

If you wished to be really certain that it will match correctly, you could also use the normalize-space function to clean up stray whitespace characters around the class name (as mentioned by @Terry):

//div[contains(concat(' ', normalize-space(@class), ' '), ' Test ')]

Note that in all these versions, the * should best be replaced by whatever element name you actually wish to match, unless you wish to search each and every element in the document for the given condition.

Java – How to read XML using XPath in Java

You need something along the lines of this:

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse(<uri_as_string>);
XPathFactory xPathfactory = XPathFactory.newInstance();
XPath xpath = xPathfactory.newXPath();
XPathExpression expr = xpath.compile(<xpath_expression>);

Then you call expr.evaluate() passing in the document defined in that code and the return type you are expecting, and cast the result to the object type of the result.

If you need help with a specific XPath expressions, you should probably ask it as separate questions (unless that was your question in the first place here - I understood your question to be how to use the API in Java).

Edit: (Response to comment): This XPath expression will get you the text of the first URL element under PowerBuilder:

/howto/topic[@name='PowerBuilder']/url/text()

This will get you the second:

/howto/topic[@name='PowerBuilder']/url[2]/text()

You get that with this code:

expr.evaluate(doc, XPathConstants.STRING);

If you don't know how many URLs are in a given node, then you should rather do something like this:

XPathExpression expr = xpath.compile("/howto/topic[@name='PowerBuilder']/url");
NodeList nl = (NodeList) expr.evaluate(doc, XPathConstants.NODESET);

And then loop over the NodeList.

Best Solution

Related Solutions

Html – How to find an element by CSS class with XPath

Java – How to read XML using XPath in Java

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