Php 如何将现有元素从XML文件B添加到XML文件A

我有2个XML文件

我试图从XML文件B中获取数据并将其添加到XML文件A中。我想首先向XML文件A中添加一个空的子元素，然后在该子元素中，我想从XML文件B中添加数据（在本例中，是

animal

child元素）。我想通过SimpleXML或DOMDocument实现这一点。我一直被困在这个问题上。任何帮助都会很好

personinfo.xml

<personinfo>
    <personN number="1">
        <personL letter="A">
            <fullname>
                <firstname>Summer</firstname>
                <lastname>Smith</lastname>
            </fullname>
            <favourites>
                <color>pink</color>
            </favourites>
        </personL>  
    </personN>

    <personN number="2">
        <personL letter="B">
            <fullname>
                <firstname>Autumn</firstname>
                <lastname>Smith</lastname>
            </fullname>
            <favourites>
                <color>blue</color>
            </favourites>
        </personL>  
    </personN>
</personinfo>

期望输出

<personinfo>
    <personN number="1">
        <personL letter="A">
            <fullname>
                <firstname>Summer</firstname>
                <lastname>Smith</lastname>
            </fullname>
            <favourites>
                <color>pink</color>
            </favourites>
            <favourites>
                <color>cat</color>
            </favourites>
        </personL>  
    </personN>

    <personN number="2">
        <personL letter="B">
            <fullname>
                <firstname>Autumn</firstname>
                <lastname>Smith</lastname>
            </fullname>
            <favourites>
                <color>blue</color>
            </favourites>
            <favourites>
                <color>dog</color>
            </favourites>
        </personL>  
    </personN>
</personinfo>

夏天
史密斯
粉红色
猫
秋
史密斯
蓝色
狗

这在DOM中更容易，因为您可以访问节点，并可以将它们从一个文档复制到另一个文档。使用Xpath获取文档的某些部分

// load the XML into DOM document and create Xpath instances
$personsDocument = new DOMDocument;
$personsDocument->preserveWhiteSpace = FALSE;
$personsDocument->loadXML($xmlPersons);
$personsXpath = new DOMXpath($personsDocument);

$favoritesDocument = new DOMDocument;
$favoritesDocument->preserveWhiteSpace = FALSE;
$favoritesDocument->loadXML($xmlFavorites);
$favoritesXpath = new DOMXpath($favoritesDocument);

// iterate the personN nodes in the favorties XML
foreach ($favoritesXpath->evaluate('.//personN') as $personFavorites) {
    $personId = (int)$personFavorites->getAttribute('number');
    // find the matching personL node in the persons XML
    foreach ($personsXpath->evaluate('.//personN[@number='.$personId.']/personL') as $personNode) {
        // check if it has a 'favourites' child already
        $favoritesNode = $personsXpath->evaluate('favourites', $personNode)->item(0);
        if (!$favoritesNode) {
            // otherwise create one
            $favoritesNode = $personNode->appendChild(
                $personsDocument->createElement('favourites')
            );
        }
        // now iterate the different favorites of a person
        foreach ($personFavorites->childNodes as $favorite) {
            // import and add
            $favoritesNode->appendChild($personsDocument->importNode($favorite, TRUE));
        }
    }
}

$personsDocument->formatOutput = TRUE;
echo $personsDocument->saveXML();

输出：

<?xml version="1.0"?>
<personinfo>
  <personN number="1">
    <personL letter="A">
      <fullname>
        <firstname>Summer</firstname>
        <lastname>Smith</lastname>
      </fullname>
      <favourites>
        <color>pink</color>
        <animal>cat</animal>
      </favourites>
    </personL>
  </personN>
  <personN number="2">
    <personL letter="B">
      <fullname>
        <firstname>Autumn</firstname>
        <lastname>Smith</lastname>
      </fullname>
      <favourites>
        <color>blue</color>
        <animal>dog</animal>
      </favourites>
    </personL>
  </personN>
</personinfo>

---

据我所知，纯SimpleXMLElement不允许从另一个现成文档导入节点，但DOMDocument允许

幸运的是，两者都能很好地协同工作，SimpleXMLElement可以“转换”为DOMNode，反之亦然

这就是为什么

下面是一个与您问题中的示例相关的示例，但不是使用

SimpleXML:：addChild（）

导入DOM，然后将（再次导入的）子节点添加到DomeElement节点：

$parent = dom_import_simplexml($newFave); # [1]
$parent->appendChild( # [2]
    $parent->ownerDocument->importNode(dom_import_simplexml($animal), true) # [3]
);

echo $personXML->asXML(); # [4]

为

父元素创建DOM节点

在DOM父节点上追加子节点

创建并导入动物最喜爱的DOM节点。需要首先将节点导入到父文档，因为它是不同DOMDocument的一部分，并且只有当节点是同一文档的一部分时，才能添加子节点

使用SimpleXMLElement输出

结果（以难看的字体）如下所示：

...
        <personL letter="A">
            <fullname>
                <firstname>Summer</firstname>
                <lastname>Smith</lastname>
            </fullname>
            <favourites>
                <color>pink</color>
            </favourites>
        <favourites><animal>cat</animal></favourites></personL>
               ^       ^
               |       |
               |   $animal = $faveXML->personN[0]->animal;
               |   $parent->ownerDocument
               |       ->importNode(dom_import_simplexml($animal), true)
               |
               |

   $newFave = $personXML->personN->personL[0]->addChild("favourites");
...

• 进一步参考：

foreach ($personsXpath->evaluate('.//personN[@number='.$personId.']/personL') as $personNode) {
    //create 'favourites' child
    $favoritesNode = $personNode->appendChild(
        $personsDocument->createElement('favourites')
    );
    foreach ($personFavorites->childNodes as $favorite) {
    //...

$parent = dom_import_simplexml($newFave); # [1]
$parent->appendChild( # [2]
    $parent->ownerDocument->importNode(dom_import_simplexml($animal), true) # [3]
);

echo $personXML->asXML(); # [4]

...
        <personL letter="A">
            <fullname>
                <firstname>Summer</firstname>
                <lastname>Smith</lastname>
            </fullname>
            <favourites>
                <color>pink</color>
            </favourites>
        <favourites><animal>cat</animal></favourites></personL>
               ^       ^
               |       |
               |   $animal = $faveXML->personN[0]->animal;
               |   $parent->ownerDocument
               |       ->importNode(dom_import_simplexml($animal), true)
               |
               |

   $newFave = $personXML->personN->personL[0]->addChild("favourites");
...

foreach ($faveXML->xpath('./personN[*]') as $person) {
    foreach ($personXML->xpath(
        sprintf('./personN[@number = "%d"]/*/favourites[1]', $person['number'])
    ) as $favourites) {
        $parent = dom_import_simplexml($favourites);
        $parent->appendChild(
            $parent->ownerDocument->importNode(dom_import_simplexml($person->children()[0]), true)
        );
    }
};