Create XML attribute using XPath-CodePudding

I want to create an xml attribute but in order to find the element I want to add the query on, I need to use xpath. How can I do this?

Example =

const xmlText = `<?xml version="1.0" encoding="ISO-8859-1"?>
<bookstore>
<book>
  <title lang="eng">Harry Potter</title>
  <price>29.99</price>
</book>
<book>
  <title id="somethingeng">Learning XML</title>
  <price>39.95</price>
</book>
</bookstore>`;

var doc = new DOMParser().parseFromString(xmlText,'text/xml');

var r = doc.evaluate("//*[@lang[contains(.,'eng')]]", doc, null, XPathResult.ANY_TYPE, null);

I want to create an attribute for this r;

CodePudding user response：

First of all the xmlText string should be a template literals now that is has new lines.

evaluate() seamed fine, but the result of that is a XPathResult that needs to be iterated with XPathResult.iterateNext().

const xmlText = `<?xml version="1.0" encoding="ISO-8859-1"?>
<bookstore>
<book>
  <title lang="eng">Harry Potter</title>
  <price>29.99</price>
</book>
<book>
  <title id="somethingeng">Learning XML</title>
  <price>39.95</price>
</book>
</bookstore>`;

var doc = new DOMParser().parseFromString(xmlText,'text/xml');

var r = doc.evaluate("//*[@lang[contains(.,'eng')]]", doc, null, XPathResult.ANY_TYPE, null);

var next = r.iterateNext();
while (next) {
  console.log(next.textContent);
  next = r.iterateNext();
}

Update

Based on the iterator you need to collect the nodes that you are interested in and then alter them afterwards. In the following I created functions that can create child elements and attributes based on a XPath expression and an object representing the new data.

const xmlText = `<?xml version="1.0" encoding="ISO-8859-1"?>
<bookstore>
<book>
  <title lang="eng">Harry Potter</title>
  <price>29.99</price>
</book>
<book>
  <title id="somethingeng">Learning XML</title>
  <price>39.95</price>
</book>
</bookstore>`;

var doc = new DOMParser().parseFromString(xmlText, 'text/xml');

function addAttribute(doc, xpath, obj) {
  let r = doc.evaluate(xpath, doc, null, XPathResult.ANY_TYPE, null);

  let nodes = [];
  let next = r.iterateNext();
  while (next) {
    nodes.push(next);
    next = r.iterateNext();
  }

  nodes.forEach(node => {
    Object.keys(obj).forEach(key => {
      let newattr = doc.createAttribute(key);
      newattr.value = obj[key];
      node.setAttributeNode(newattr);
    });
  });
}

function addChildNode(doc, xpath, obj) {
  let r = doc.evaluate(xpath, doc, null, XPathResult.ANY_TYPE, null);

  let nodes = [];
  let next = r.iterateNext();
  while (next) {
    console.log(next.textContent);
    nodes.push(next);
    next = r.iterateNext();
  }

  nodes.forEach(node => {
    Object.keys(obj).forEach(key => {
      let newnode = doc.createElement(key);
      newnode.textContent = obj[key];
      node.appendChild(newnode);
    });
  });
}



addAttribute(doc, "//title[@lang[contains(.,'eng')]]", {"data-lang":"eng", index: 2});
addChildNode(doc, "//book[number(price) < 30]", {sale: true});

console.log(doc.documentElement.outerHTML);

CodePudding user response：

Found the solution by using XPathResult.snapshotItem().

var xmlText = `<?xml version="1.0" encoding="ISO-8859-1"?>
  <bookstore>
    <book>
      <title lang="eng">Harry Potter</title>
      <price>29.99</price>
    </book>
    
    <book>
      <title id=\"somethingeng\">Learning XML</title>
      <price>39.95</price>
    </book>
    
  </bookstore>`;

var doc = new DOMParser().parseFromString(xmlText, 'text/xml');
var r = doc.evaluate("//*[@id[contains(.,'eng')]]", doc, null, XPathResult.ORDERED_NODE_SNAPSHOT_TYPE, null);

var index = 0;
while (index < r.snapshotLength) {
  var next = r.snapshotItem(index);
  next.setAttribute("value", "val");
  index  ;
}

var xmlSerializer = new XMLSerializer();
const updatedDoc = xmlSerializer.serializeToString(doc);

console.log(updatedDoc);