Server-side JavaScript

Working with XML

Everything’s a node in a MarkLogic database: JSON, XML, binary, and text. JavaScript provides syntax for working with JSON nodes, mapping them to plain old JavaScript objects. No such equivalent is built into the language for XML. The NodeBuilder API provides a lightweight interface for constructing XML nodes from JavaScript. XML nodes can also be constructed from strings using xdmp.unquote(). Like a JSON node, an XML node can be saved in the database or manipulated using either Server-side JavaScript or XQuery. XML nodes support a read-only W3C DOM interface for reading and traversing node structures. Additionally, any XDM function that takes a node as its first parameter in XQuery can also be called as property of an XMLNode.

var nb = new NodeBuilder();
nb.startDocument()
  .startElement('ex:article', 'http://example.com')
    .addAttribute('is-draft','true');
    for (var i = 0; i < 17; i++) {
      nb.startElement('ex:p', 'http://example.com')
        .addText('This is paragraph ') + 
          nb.startElement('em', '') // No namespace
            .addText((i + 1).toString())
            .endElement()
        .addText('.')
      .endElement();
    }
  nb.endElement()
    .endDocument();
var xml = nb.toNode();

// An XMLNode is how XML is represented in Server-Side JavaScript. Like JSON 
// ObjectNodes, XMLNodes are immutable. Use NodeBuilder to construct XML or 
// literal JavaScript objects to build JSON nodes in JavaScript. 
xml instanceof XMLNode && xml instanceof Node && xml instanceof Value; // true

for (var element of xml.xpath('//ex:p', {'ex': 'http://example.com'})) {
  // All XMLNode instances support a read-only w3c DOM interface
  var text = element.textContent;
  // typeof text === 'string'
  var children = element.childNodes; 
  // children instanceof NodeList && children.length === 3

  // …as well as any node function, i.e. any XDM function that takes a node as the first argument
  // For example, to validate against a schema:
  //   element.validate();
  // is equivalent to 
  //   xdmp.validate(element);
}

XPath

Because JSON nodes in the database are nodes, in the XML Document Model (XDM) sense, you can access them with XPath. This provides a powerful way to drill down into XML content. To use this from Server-side JavaScript, you can call xdmp.xqueryEval(), passing in an expression, or apply the xpath() function to an XMLNode. The code above has an example of using the .xpath() function.

/*
 * Evaluate standard XPath against JSON (or XML or both). JSON properties operate similar to unnamespaced
 * XML elements.
 */
var total = 0, count = 0;
// XPath is a subset of XQuery. Evaluate it.
var resultIter = 
  xdmp.xqueryEval('/node()[some $name in friends/name satisfies starts-with(upper-case($name), "N") or eyeColor = "blue"]');
for (var result of resultIter) {
  total += result.age;
  count++;
};
"Average age of people who have blue eyes or are friends with others whose names start with \"N\": " + (total/count);

From XPath, JSON properties look like un-namespaced XML elements. MarkLogic also extends the XDM with object-node() and array-node() types.

/*
 * Use node() to match any XML or JSON node, including unnamed object nodes at the "root" of a JSON document. 
 * The new object-node() and array-node() match only their JSON namesakes.
 * (Note: Don't run this code on a large database. It brings back every document and its properties multiple times.)
 */
[
  "All nodes ===============================================================================================",
  xdmp.xqueryEval("//node()"),
  "All \"root\" nodes. These are unnamed for JSON documents ================================================",
  xdmp.xqueryEval("/node()"),
  "All nodes types =========================================================================================",
  xdmp.xqueryEval("//node()/xdmp:node-kind(.)"),
  "All object nodes ========================================================================================",
  xdmp.xqueryEval("//object-node()"),
  "All array nodes =========================================================================================",
  xdmp.xqueryEval("//array-node()"),
]

Stack Overflow: Get the most useful answers to questions from the MarkLogic community, or ask your own question.

MarkLogic

Semaphore

OpenEdge

DataDirect

Sitefinity

Telerik

Kendo UI

Corticon

DataDirect

MOVEit

Chef

Flowmon

Kemp LoadMaster

WhatsUp Gold

Telerik

Kendo UI

Fiddler

Test Studio

MOVEit

WS_FTP

Contents

Server-side JavaScript

Working with XML

XPath