Parsing and editing XML with Google Apps Script

Question

I've been looking for a way to parse and edit XML using Google Apps Script. Parsing the data using the in-built Xml class is easy enough but this doesn't let me edit any of the data. Take for example the example XML:

<?xml version='1.0' encoding='UTF-8'?>
<entry xmlns='http://www.w3.org/2005/Atom' xmlns:gContact='http://schemas.google.com/contact/2008' xmlns:batch='http://schemas.google.com/gdata/batch' xmlns:gd='http://schemas.google.com/g/2005' gd:etag='&quot;Xh9QE00OESt7I2Bp&quot;'>
<id>http://www.google.com/m8/feeds/profiles/domain/test.com/full/user</id>
<info>Test Info</info>
</entry>

Say I'm looking to modify the info entry. Currently I'm just keeping the whole thing as a string, using indexOf("<info>") to find where the entry starts and replacing the test from there to indexOf("</info>"). This seems to work but I don't think it's that reliable (if the tag has an attribute it will fail to find it).

I saw another thread on here were someone suggested using XML (not Xml) to modify the attributes, but I can't figure out how to parse the existing xml I have (retrieved with UrlFetchApp into a string) into the object.

Does anyone have any suggestions on this, it would be gratefully appreciated.

Answer 1

In case anyone finds this in the future (hello future people, how are the flying cars and robot maids?), I wasn't able to find a way to parse and edit xml in apps script so I wrote up my own json to xml functions that worked for me (processing data from the google profile api). I haven't tested it with much else so you will probably have to modify them if you want to use them.

function xmlToJson(xmlElement) {
  var e = {"namespace" : xmlElement.getName().getNamespace(),
           "name" : xmlElement.getName().getLocalName()};
  var xmlAs = xmlElement.getAttributes();
  if(xmlAs.length > 0) {
    e.attributes = {};
    for(var j = 0; j < xmlAs.length; j++) {
      e.attributes[xmlAs[j].getName().getLocalName()] = {"namespace" : xmlAs[j].getName().getNamespace(),
                                                         "name" : xmlAs[j].getName().getLocalName(),
                                                         "value" : xmlAs[j].getValue()};
    }
  }

  var xmlChildren = xmlElement.getElements();
  if(xmlChildren.length > 0) {
    e.children = {};
    for(var i = 0; i < xmlChildren.length; i++){
      var child = xmlToJson(xmlChildren[i]);
      if(typeof e.children[child.name] != "undefined")
        e.children[child.name].push(child);
      else
        e.children[child.name] = [child];
    }
  } else {
    e.value = xmlElement.getText();
  }
  return e;
}

function jsonToXmlString(json) {
  var xml = "<?xml version='1.0' encoding='UTF-8'?>";
  var namespaces = new Object(); // List of things which are possibly namespaces
  namespaces["http://www.w3.org/2000/xmlns/"] = "xmlns";

  function appendNode(node) {
    if(typeof node.attributes != 0) {
      var attributes = ""; // Get attributes first incase any are namespaces
      var keys = getKeys(node.attributes);
      for(var i = 0; i < keys.length; i++) { // Loop through attributes once to get namespaces
        if(node.attributes[keys[i]].value.indexOf("http") == 0) // Possible namespace, store in namespaces
          namespaces[node.attributes[keys[i]].value] = node.attributes[keys[i]].name;
      }
      // If we only do one loop, there may be some namespaces on attributes that don't get recorded first
      for(var i = 0; i < keys.length; i++) { 
        if(node.attributes[keys[i]].namespace != "") // Get namespace if needed
          var ns = (namespaces[node.attributes[keys[i]].namespace] || node.attributes[keys[i]].namespace) + ":";
        else
          var ns = "";
        attributes += " " + ns + node.attributes[keys[i]].name + "='" + node.attributes[keys[i]].value + "'"; 
      }
    }
    if(node.namespace != "") // Get namespace if needed
      var ns = (namespaces[node.namespace] || node.namespace) + ":";
    else
      var ns = "";

    xml += "<" + ns + node.name + attributes;

    if(typeof node.children != "undefined") { 
      xml += ">";
      var cKeys = getKeys(node.children);
      for(var i = 0; i < cKeys.length; i++) {
        for(var j = 0; j < node.children[cKeys[i]].length; j++)
          appendNode(node.children[cKeys[i]][j]);
      }
    } else if(typeof node.value != "undefined") {
      xml += ">" + node.value;
    } else {
      xml += "/>";
      return
    }

    xml += "</" + ns + node.name + ">"
  }

  appendNode(json);
  return xml;
}