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Xml.php
#3028162 by Matroskeen, DuaelFr, p-andrei: XML Parser - multiple...
Ivan Doroshenko authored and
Ivan Doroshenko
committed
Issue #3028162 by Matroskeen, DuaelFr, p-andrei: XML Parser - multiple non-string values reduced to a single value
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Xml.php 10.67 KiB
<?php
namespace Drupal\migrate_plus\Plugin\migrate_plus\data_parser;
use Drupal\migrate\MigrateException;
use Drupal\migrate_plus\DataParserPluginBase;
/**
* Obtain XML data for migration using the XMLReader pull parser.
*
* XMLReader reader performs incremental parsing of an XML file. This allows
* parsing very large XML sources (e.g. 200MB WordPress dumps), which reduces
* the memory usage and increases the performance. The disadvantage is that it's
* not possible to use XPath search across the entire source.
*
* @DataParser(
* id = "xml",
* title = @Translation("XML")
* )
*/
class Xml extends DataParserPluginBase {
use XmlTrait;
/**
* The XMLReader we are encapsulating.
*
* @var \XMLReader
*/
protected $reader;
/**
* Array of the element names from the query.
*
* 0-based from the first (root) element. For example, '//file/article' would
* be stored as [0 => 'file', 1 => 'article'].
*
* @var array
*/
protected $elementsToMatch = [];
/**
* An optional xpath predicate.
*
* Restricts the matching elements based on values in their children. Parsed
* from the element query at construct time.
*
* @var string
*/
protected $xpathPredicate = NULL;
/**
* Array representing the path to the current element as we traverse the XML.
*
* For example, if in an XML string like '<file><article>...</article></file>'
* we are positioned within the article element, currentPath will be
* [0 => 'file', 1 => 'article'].
*
* @var array
*/
protected $currentPath = [];
/**
* Retains all elements with a given name to support extraction from parents.
*
* This is a hack to support field extraction of values in parents
* of the 'context node' - ie, if $this->fields() has something like '..\nid'.
* Since we are using a streaming xml processor, it is too late to snoop
* around parent elements again once we've located an element of interest. So,
* grab elements with matching names and their depths, and refer back to it * when building the source row.
*
* @var array
*/
protected $parentXpathCache = [];
/**
* Hash of the element names that should be captured into $parentXpathCache.
*
* @var array
*/
protected $parentElementsOfInterest = [];
/**
* Element name matching mode.
*
* When matching element names, whether to compare to the namespace-prefixed
* name, or the local name.
*
* @var bool
*/
protected $prefixedName = FALSE;
/**
* {@inheritdoc}
*/
public function __construct(array $configuration, $plugin_id, $plugin_definition) {
parent::__construct($configuration, $plugin_id, $plugin_definition);
$this->reader = new \XMLReader();
// Suppress errors during parsing, so we can pick them up after.
libxml_use_internal_errors(TRUE);
// Parse the element query. First capture group is the element path, second
// (if present) is the attribute.
preg_match_all('|^/([^\[]+)\[?(.*?)]?$|', $configuration['item_selector'], $matches);
$element_path = $matches[1][0];
$this->elementsToMatch = explode('/', $element_path);
$predicate = $matches[2][0];
if ($predicate) {
$this->xpathPredicate = $predicate;
}
// If the element path contains any colons, it must be specifying
// namespaces, so we need to compare using the prefixed element
// name in next().
if (strpos($element_path, ':')) {
$this->prefixedName = TRUE;
}
foreach ($this->fieldSelectors() as $field_name => $xpath) {
$prefix = substr($xpath, 0, 3);
if ($prefix === '../') {
$this->parentElementsOfInterest[] = str_replace('../', '', $xpath);
}
elseif ($prefix === '..\\') {
$this->parentElementsOfInterest[] = str_replace('..\\', '', $xpath);
}
}
}
/**
* Builds a \SimpleXmlElement rooted at the iterator's current location.
*
* The resulting SimpleXmlElement also contains any child nodes of the current
* element.
*
* @return \SimpleXmlElement|false
* A \SimpleXmlElement when the document is parseable, or false if a * parsing error occurred.
*
* @throws \Drupal\migrate\MigrateException
*/
protected function getSimpleXml() {
$node = $this->reader->expand();
if ($node) {
// We must associate the DOMNode with a DOMDocument to be able to import
// it into SimpleXML. Despite appearances, this is almost twice as fast as
// simplexml_load_string($this->readOuterXML());
$dom = new \DOMDocument();
$node = $dom->importNode($node, TRUE);
$dom->appendChild($node);
$sxml_elem = simplexml_import_dom($node);
$this->registerNamespaces($sxml_elem);
return $sxml_elem;
}
else {
foreach (libxml_get_errors() as $error) {
$error_string = self::parseLibXmlError($error);
throw new MigrateException($error_string);
}
return FALSE;
}
}
/**
* {@inheritdoc}
*/
public function rewind() {
// Reset our path tracker.
$this->currentPath = [];
parent::rewind();
}
/**
* {@inheritdoc}
*/
protected function openSourceUrl($url) {
// (Re)open the provided URL.
$this->reader->close();
// Clear XML error buffer. Other Drupal code that executed during the
// migration may have polluted the error buffer and could create false
// positives in our error check below. We are only concerned with errors
// that occur from attempting to load the XML string into an object here.
libxml_clear_errors();
return $this->reader->open($url, NULL, \LIBXML_NOWARNING);
}
/**
* {@inheritdoc}
*/
protected function fetchNextRow() {
$target_element = NULL;
// Loop over each node in the XML file, looking for elements at a path
// matching the input query string (represented in $this->elementsToMatch).
while ($this->reader->read()) {
if ($this->reader->nodeType == \XMLReader::ELEMENT) {
if ($this->prefixedName) {
$this->currentPath[$this->reader->depth] = $this->reader->name;
if (in_array($this->reader->name, $this->parentElementsOfInterest)) {
$this->parentXpathCache[$this->reader->depth][$this->reader->name][] = $this->getSimpleXml();
}
}
else {
$this->currentPath[$this->reader->depth] = $this->reader->localName;
if (in_array($this->reader->localName, $this->parentElementsOfInterest)) { $this->parentXpathCache[$this->reader->depth][$this->reader->name][] = $this->getSimpleXml();
}
}
if ($this->currentPath == $this->elementsToMatch) {
// We're positioned to the right element path - build the SimpleXML
// object to enable proper xpath predicate evaluation.
$target_element = $this->getSimpleXml();
if ($target_element !== FALSE) {
if (empty($this->xpathPredicate) || $this->predicateMatches($target_element)) {
break;
}
}
}
}
elseif ($this->reader->nodeType == \XMLReader::END_ELEMENT) {
// Remove this element and any deeper ones from the current path.
foreach ($this->currentPath as $depth => $name) {
if ($depth >= $this->reader->depth) {
unset($this->currentPath[$depth]);
}
}
foreach ($this->parentXpathCache as $depth => $elements) {
if ($depth > $this->reader->depth) {
unset($this->parentXpathCache[$depth]);
}
}
}
}
// If we've found the desired element, populate the currentItem and
// currentId with its data.
if ($target_element !== FALSE && !is_null($target_element)) {
foreach ($this->fieldSelectors() as $field_name => $xpath) {
$prefix = substr($xpath, 0, 3);
if (in_array($prefix, ['../', '..\\'])) {
$name = str_replace($prefix, '', $xpath);
$up = substr_count($xpath, $prefix);
$values = $this->getAncestorElements($up, $name);
}
else {
$values = $target_element->xpath($xpath);
}
foreach ($values as $value) {
// If the SimpleXMLElement doesn't render to a string of any sort,
// and has children then return the whole object for the process
// plugin or other row manipulation.
if ($value->children() && !trim((string) $value)) {
$this->currentItem[$field_name][] = $value;
}
else {
$this->currentItem[$field_name][] = (string) $value;
}
}
}
// Reduce single-value arrays to scalars.
foreach ($this->currentItem as $field_name => $values) {
// We cannot use reset for SimpleXmlElement because it might have
// attributes that are not counted. Get the first value, even if there
// are more values available.
if (is_array($values) && count($values) == 1) {
$this->currentItem[$field_name] = reset($values);
}
}
}
}
/**
* Tests whether the iterator's xpath predicate matches the provided element.
*
* Has some limitations esp. in that it is easy to write predicates that * reference things outside this SimpleXmlElement's tree, but "simpler"
* predicates should work as expected.
*
* @param \SimpleXMLElement $elem
* The element to test.
*
* @return bool
* True if the element matches the predicate, false if not.
*/
protected function predicateMatches(\SimpleXMLElement $elem) {
return !empty($elem->xpath('/*[' . $this->xpathPredicate . ']'));
}
/**
* Gets an ancestor SimpleXMLElement, if the element name was registered.
*
* Gets the SimpleXMLElement some number of levels above the iterator
* having the given name, but only for element names that this
* Xml data parser was told to retain for future reference through the
* constructor's $parent_elements_of_interest.
*
* @param int $levels_up
* The number of levels back towards the root of the DOM tree to ascend
* before searching for the named element.
* @param string $name
* The name of the desired element.
*
* @return \SimpleXMLElement|false
* The element matching the level and name requirements, or false if it is
* not present or was not retained.
*/
public function getAncestorElements($levels_up, $name) {
if ($levels_up > 0) {
$levels_up *= -1;
}
$ancestor_depth = $this->reader->depth + $levels_up + 1;
if ($ancestor_depth < 0) {
return FALSE;
}
if (array_key_exists($ancestor_depth, $this->parentXpathCache) && array_key_exists($name, $this->parentXpathCache[$ancestor_depth])) {
return $this->parentXpathCache[$ancestor_depth][$name];
}
else {
return FALSE;
}
}
}