如何在 JavaScript 中处理 XPath 的子元素中的命名空间声明？

Question

我正在尝试使用MDN: Introduction to using XPath in JavaScript 中指定的 XPath 和 XML。但是，当我尝试按原样使用我的 XML 时，它导致了一个错误（见下文）

const xmlStr = `<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" 
    xmlns:n0="http://tempuri.org/">
    <soapenv:Header>
    </soapenv:Header>
    <soapenv:Body>
        <n0:SavePartnerDetailsWithToken xmlns:n2="http://schemas.microsoft.com/2003/10/Serialization/Arrays">
            <n0:userToken></n0:userToken>
            <n2:myNode>valueHere</n2:myNode>
        </n0:SavePartnerDetailsWithToken>
    </soapenv:Body>
</soapenv:Envelope>`;
const xmlObj = new DOMParser().parseFromString(xmlStr, 'application/xml');
const nsResolver = xmlObj.createNSResolver(xmlObj.ownerDocument === null ? xmlObj.documentElement : xmlObj.ownerDocument.documentElement);
firstNode = xmlObj.evaluate('/soapenv:Envelope/soapenv:Body/n0:SavePartnerDetailsWithToken/n2:myNode', xmlObj, nsResolver, XPathResult.FIRST_ORDERED_NODE_TYPE, null);
console.log(firstNode.singleNodeValue.textContent)

然后我将所有 xmlns: 属性移动到根目录，因为 createNSResolver() 方法需要 documentElement 作为参数。

const xmlStr = `<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" 
    xmlns:n0="http://tempuri.org/"
    xmlns:n2="http://schemas.microsoft.com/2003/10/Serialization/Arrays">
    <soapenv:Header>
    </soapenv:Header>
    <soapenv:Body>
        <n0:SavePartnerDetailsWithToken>
            <n0:userToken></n0:userToken>
            <n2:myNode>valueHere</n2:myNode>
        </n0:SavePartnerDetailsWithToken>
    </soapenv:Body>
</soapenv:Envelope>`;
const xmlObj = new DOMParser().parseFromString(xmlStr, 'application/xml');
const nsResolver = xmlObj.createNSResolver(xmlObj.ownerDocument === null ? xmlObj.documentElement : xmlObj.ownerDocument.documentElement);
firstNode = xmlObj.evaluate('/soapenv:Envelope/soapenv:Body/n0:SavePartnerDetailsWithToken/n2:myNode', xmlObj, nsResolver, XPathResult.FIRST_ORDERED_NODE_TYPE, null);
console.log(firstNode.singleNodeValue.textContent)

这行得通。但是，我无法确保命名空间声明位于运行时上传到我的应用程序的 XML 的根元素上。我想知道

• 可以创建XPathNSResolver，以便考虑根中的命名空间声明以及所有子元素。或
• xmlns: 声明可以提升到根目录。

也欢迎其他解决方案！

Answer 1

我想出了一个函数来实现第二种方法。然而，即使在应用了函数 xmlObj 之后，仍然不能直接用于给定的 XPath。 xmlObj 需要反序列化和重新序列化（参见 sn-p 中的第 41 和 42 行）才能成功评估 XPath。

function hoistNameSpaceAttributesToRoot(DOMNode) {
	if (DOMNode instanceof Element) {
		if (DOMNode.hasAttributes() && DOMNode !== DOMNode.ownerDocument.documentElement) {
			const attrs = DOMNode.attributes;
			for (let i = attrs.length - 1; i >= 0; i--) {
				if (attrs[i].name.startsWith('xmlns:')) {
					DOMNode.ownerDocument.documentElement.setAttribute(attrs[i].name, attrs[i].value);
					DOMNode.removeAttribute(attrs[i].name);
				}
			}
			if (DOMNode.hasAttribute('xmlns')) {
				DOMNode.removeAttribute('xmlns');
			}
		}
	}
	// First check that the element has child nodes
	if (DOMNode.hasChildNodes()) {
		const children = DOMNode.childNodes;

		// tslint:disable-next-line: prefer-for-of
		for (let i = 0; i < children.length; i++) {
			// do something with each child as children[i]
			// NOTE: List is live, adding or removing children will change the list
			this.hoistNameSpaceAttributesToRoot(children[i]);
		}
	}
}
let xmlStr = `<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" 
    xmlns:n0="http://tempuri.org/">
    <soapenv:Header>
    </soapenv:Header>
    <soapenv:Body>
        <n0:SavePartnerDetailsWithToken xmlns:n2="http://schemas.microsoft.com/2003/10/Serialization/Arrays">
            <n0:userToken></n0:userToken>
            <n2:myNode>valueHere</n2:myNode>
        </n0:SavePartnerDetailsWithToken>
    </soapenv:Body>
</soapenv:Envelope>`;
let xmlObj = new DOMParser().parseFromString(xmlStr, 'application/xml');
hoistNameSpaceAttributesToRoot(xmlObj);
xmlStr = new XMLSerializer().serializeToString(xmlObj);
xmlObj = new DOMParser().parseFromString(xmlStr, 'application/xml');
const nsResolver = xmlObj.createNSResolver(xmlObj.ownerDocument === null ? xmlObj.documentElement : xmlObj.ownerDocument.documentElement);
const firstNode = xmlObj.evaluate('/soapenv:Envelope/soapenv:Body/n0:SavePartnerDetailsWithToken/n2:myNode', xmlObj, nsResolver, XPathResult.FIRST_ORDERED_NODE_TYPE, null);
console.log(firstNode.singleNodeValue.textContent)