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[DomCrawler] Add support for XPath expression evaluation #19430

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Merged
merged 1 commit into from
Aug 2, 2016
Merged

[DomCrawler] Add support for XPath expression evaluation #19430

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30 changes: 30 additions & 0 deletions src/Symfony/Component/DomCrawler/Crawler.php
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Original file line number Diff line number Diff line change
Expand Up @@ -592,6 +592,36 @@ public function html()
return $html;
}

/**
* Evaluates an XPath expression.
*
* Since an XPath expression might evaluate to either a simple type or a \DOMDoneList,
* this method will return either an array of simple types or a new Crawler instance.
*
* @param string $xpath An XPath expression
*
* @return array|Crawler An array of evaluation results or a new Crawler instance
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returning an array of a Crawler makes it difficult to work with this method in a fluent interface. This would be the first method returning a Crawler or something else.

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Yeah, I thought twice before defining the return type. I also don't like it but the DOMXPath::evaluate() returns a simple type value or DOMNodeList. The result depends on the type of xpath query. I figured that the end user knows what it's gonna be since he wrote the query.

Not sure how we could solve it differently (other than defining two methods and verifying results, or forbidding one type of queries).

*/
public function evaluate($xpath)
{
if (null === $this->document) {
throw new \LogicException('Cannot evaluate the expression on an uninitialized crawler.');
}

$data = array();
$domxpath = $this->createDOMXPath($this->document, $this->findNamespacePrefixes($xpath));

foreach ($this->nodes as $node) {
$data[] = $domxpath->evaluate($xpath, $node);
}

if (isset($data[0]) && $data[0] instanceof \DOMNodeList) {
return $this->createSubCrawler($data);
}

return $data;
}

/**
* Extracts information from the list of nodes.
*
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45 changes: 45 additions & 0 deletions src/Symfony/Component/DomCrawler/Tests/CrawlerTest.php
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Expand Up @@ -1061,6 +1061,51 @@ public function testCountOfNestedElements()
$this->assertCount(1, $crawler->filter('li:contains("List item 1")'));
}

public function testEvaluateReturnsTypedResultOfXPathExpressionOnADocumentSubset()
{
$crawler = $this->createTestCrawler();

$result = $crawler->filterXPath('//form/input')->evaluate('substring-before(@name, "Name")');

$this->assertSame(array('Text', 'Foo', 'Bar'), $result);
}

public function testEvaluateReturnsTypedResultOfNamespacedXPathExpressionOnADocumentSubset()
{
$crawler = $this->createTestXmlCrawler();

$result = $crawler->filterXPath('//yt:accessControl/@action')->evaluate('string(.)');

$this->assertSame(array('comment', 'videoRespond'), $result);
}

public function testEvaluateReturnsTypedResultOfNamespacedXPathExpression()
{
$crawler = $this->createTestXmlCrawler();
$crawler->registerNamespace('youtube', 'http://gdata.youtube.com/schemas/2007');

$result = $crawler->evaluate('string(//youtube:accessControl/@action)');

$this->assertSame(array('comment'), $result);
}

public function testEvaluateReturnsACrawlerIfXPathExpressionEvaluatesToANode()
{
$crawler = $this->createTestCrawler()->evaluate('//form/input[1]');

$this->assertInstanceOf(Crawler::class, $crawler);
$this->assertCount(1, $crawler);
$this->assertSame('input', $crawler->first()->nodeName());
}

/**
* @expectedException \LogicException
*/
public function testEvaluateThrowsAnExceptionIfDocumentIsEmpty()
{
(new Crawler())->evaluate('//form/input[1]');
}

public function createTestCrawler($uri = null)
{
$dom = new \DOMDocument();
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