genx

node-genx

node.js bindings to the Genx XML generation library. It is currently a work in progress. When ready it will be released to npm.

Installing

npm install genx

Building From Source

node-waf configure
node-waf build

Example

The following complete example uses Genx to reproduce the brief, single-entry Atom Feed Document in the Atom spec. The result is written to stdout. Note that Genx does not do any formatting of the XML for you so unless you insert the text nodes manually the result will all come out on one line. This is easy to fix by passing the result through xmllint (part of libxml2).

var genx = require('genx');

var w = new genx.Writer();

w.on('data', function(data) {
  process.stdout.write(data);
})

// Declare the elements and attributes up-front
var ns      = w.declareNamespace('http://www.w3.org/2005/Atom', '');
var feed    = w.declareElement(ns, 'feed');
var title   = w.declareElement(ns, 'title');
var link    = w.declareElement(ns, 'link');
var updated = w.declareElement(ns, 'updated');
var author  = w.declareElement(ns, 'author');
var name    = w.declareElement(ns, 'name');
var id      = w.declareElement(ns, 'id');
var entry   = w.declareElement(ns, 'entry');
var summary = w.declareElement(ns, 'summary');

var href    = w.declareAttribute('href');

// This is not a processing instruction and as such can't be generated by Genx
process.stdout.write("<?xml version=\"1.0\" encoding=\"utf-8\"?>\n");
w.startDocument()
  .startElement(feed)
    .startElement(title).addText("Example Feed").endElement()
    .startElement(link).addAttribute(href, "http://example.org/").endElement()
    .startElement(updated).addText("2003-12-13T18:30:02Z").endElement()
    .startElement(author)
      .startElement(name).addText("John Doe").endElement()
    .endElement()
    .startElement(id).addText("urn:uuid:60a76c80-d399-11d9-b93C-0003939e0af6").endElement()
    .startElement(entry)
      .startElement(title).addText("Atom-Powered Robots Run Amok").endElement()
      .startElement(link).addAttribute(href, "http://example.org/2003/12/13/atom03").endElement()
      .startElement(id).addText("urn:uuid:1225c695-cfb8-4ebb-aaaa-80da344efa6a").endElement()
      .startElement(updated).addText("2003-12-13T18:30:02Z").endElement()
      .startElement(summary).addText("Some text.").endElement()
    .endElement()
  .endElement()
.endDocument();

To run the example and format it with xmllint:

node genx-atom.js | xmllint --format -

API

The API pretty closely follows the underlying Genx library's API. This module exports one object, Writer, which you use to generate XML. Any errors encountered are raised as exceptions.

Note: Each of the following examples assumes the module has been imported and a Writer created as follows:

var genx = require('genx);
var writer = new genx.Writer();

Events

The Writer emits data events with a single string argument containing an XML fragment. You listen for data events in order to make use of the generated XML.

writer.on('data', function(data) {
  // Do something with the data such as write it to a file
});

Writer

The Writer class provides the primary interface to Genx. Call writer methods to generate XML. XML can be generated via literal nodes (elements, attributes) or by reusing pre-declared nodes. The Genx documentation claims that using predeclared nodes are more efficient. Where it makes sense the methods return this allowing calls to be chained. For example:

writer.startDocument().startElement(elem)

---

startDocument()

Starts an XML document. Must be called before any elements can be added. This method may be called on a Writer multiple times after completing each document with endDocument in order to re-use a Writer and generate multiple documents.

Return Value

Returns the receiver.

Example

writer.startDocument();

---

endDocument()

Ends a document previously started with startDocument.

Return Value

Returns the receiver.

Example

writer.endDocument();

---

declareNamespace(uri, [prefix])

Declares a namespace for later use in declareElement.

Arguments

• uri (mandatory, String) -- the uri of the namespace
• prefix (optional, String) -- the prefix that will be used for elements in this namespace. If the prefix is omitted Genx will generate one for you. Generated prefixes are of the form "gN", where N starts at 1. If prefix is the empty string, "", then this namespace will be set as the default namespace.

Return Value

Returns a Namespace object for later use with declareElement.

Examples

// Namespace with prefix
var ns = writer.declareNamespace('http://www.w3.org/2005/Atom', "atom");

// Default namespace
var ns = writer.declareNamespace('http://www.w3.org/2005/Atom', "");

// Generated prefix
var ns = writer.declareNamespace('http://www.w3.org/2005/Atom');

declareElement([namespace], name)

Declares an element with name name in namespace namespace. If no namespace is supplied then the element is in no namespace.

Arguments

• namespace (optional, Namespace) -- The namespace the element belongs to. Must be a Namespace object returned by declareNamespace.
• name (mandatory, String) -- The name of the element a.k.a. tag.

Return Value

Returns an Element object for later use with startElement.

Examples

// Element without a namespace
var elem = writer.declareElement('test');

// Namespaced element
var ns = writer.declareNamespace('http://www.w3.org/2005/Atom', "");
var elem = writer.declareElement(ns, 'feed');

---

declareAttribute([namespace], name)

Declares an attribute with name name in namespace namespace. If no namespace is supplied then the attribute is in no namespace.

Arguments

• namespace (optional, String) -- The namespace the attribute belongs to. Must be a Namespace object returned by declareNamespace.
• name (mandatory, String) -- The name of the attribute. The value is supplied later via addAttribute.

Return Value

Returns an Attribute object for later use with addAttribute.

Examples

// Attribute without a namespace
var elem = writer.declareElement('type');

// Namespaced attribute
var ns = writer.declareAttribute('http://www.w3.org/2005/Atom', "");
var elem = writer.declareAttribute(ns, 'type');

---

startElement(element)

Opens the element element.

Arguments

• element (mandatory, Element) -- The element to open. Must be an Element object previously declared via declareElement.

Return Value

Returns the receiver.

Example

var elem = writer.declareElement('feed');

writer.startDocument()
  .startElement(elem)
  .endElement()
.endDocument()

---

startElementLiteral([namespace], name)

Opens an element with name, name in namespace namespace (a URI) without pre-declaring it. The Genx documentation claims that pre-declaring is more efficient. Especially if the element is emitted multiple times.

Arguments

• namespace (optional, String) -- A namespace URI that the element belongs to. If a prefix for this namespace has previously been declared via declareNamespace then that prefix will be used, otherwise Genx will generate one of the form described in declareNamespace.
• name (mandatory, String) -- The name of the element to start.

Return Value

Returns the receiver.

Examples

// Without a namespace
writer.startDocument()
  .startElementLiteral('feed')
  .endElement()
.endDocument()

// With a namespace
writer.startDocument()
  .startElementLiteral('http://www.w3.org/2005/Atom', 'feed')
  .endElement()
.endDocument()

---

addText(text)

Adds a text node to the document.

Arguments

• text (mandatory, String) -- The text to add to the document.

Return Value

Returns the receiver.

Example

writer.startDocument()
  .startElementLiteral('feed')
    .addText("Some text")
  .endElement()
.endDocument()

---

addComment(comment)

Arguments

• comment (mandatory, String) -- The comment text to add to the document.

Return Value

Returns the receiver.

Example

writer.startDocument()
  .addComment("Generated " + (new Date()).toString())
  .startElementLiteral('feed')
  .endElement()
.endDocument();

---

addAttribute(attribute, value)

Arguments

• attribute (mandatory, Attribute) -- The attribute to add to the document. Must be an Attribute object previously declared via declareAttribute.
• value (mandatory, String) -- The attribute's value.

Return Value

Returns the receiver.

Example

var ns = writer.declareNamespace('http://www.w3.org/2005/Atom', '');
var feed = writer.declareElement(ns, 'feed');
var title = writer.declareElement(ns, 'title');
var type = writer.declareAttribute('type');

writer.startDocument()
  .startElement(feed)
    .startElement(title)
      .addAttribute(type, 'text')
      .addText("Test Title")
    .endElement()
  .endElement()
.endDocument();

---

addAttributeLiteral([namespace], name, value)

Arguments

• namespace (optional, String) -- A namespace URI that the attribute belongs to. If a prefix for this namespace has previously been declared via declareNamespace then that prefix will be used, otherwise Genx will generate one of the form described in declareNamespace.
• name (mandatory, String) -- The attribute's name.
• value (mandatory, String) -- The attribute's value.

Return Value

Returns the receiver.

Example

var ns = writer.declareNamespace('http://www.w3.org/2005/Atom', '');
var feed = writer.declareElement(ns, 'feed');
var title = writer.declareElement(ns, 'title');

writer.startDocument()
  .startElement(feed)
    .startElement(title)
      .addAttributeLiteral('type', 'text')
      .addText("Test Title")
    .endElement()
  .endElement()
.endDocument();

---

endElement()

Return Value

Returns the receiver.

Example

writer.startDocument()
  .startElementLiteral('feed')
  .endElement()
.endDocument()

Running the Tests

This project has a test suite in the spec directory. It is written in CoffeeScript and utilises the Jasmine BDD framwork. To run the suite you need to have the jasbin and coffee-script modules installed:

npm install jasbin coffee-script

The suite is run by running jasbin in the project root:

jasbin

# Started
# ...................................
#
# Finished in 0.032 seconds
# 21 tests, 41 assertions, 0 failures

The suite should pass on node 0.2.x and 0.3.x.

There is also a Guardfile present that enables automatically rebuilding the module and running the tests when one of the source files change. To use this you need the guard and guard-shell Ruby gems installed. This can be done as follows:

gem install guard guard-shell

Then run guard in the project root.