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node-xml2js

Ever had the urge to parse XML? And wanted to access the data in some sane, easy way? Don't want to compile a C parser, for whatever reason? Then xml2js is what you're looking for!

Description

Simple XML to JavaScript object converter. It supports bi-directional conversion. Uses sax-js and xmlbuilder-js.

Note: If you're looking for a full DOM parser, you probably want JSDom.

Installation

Simplest way to install xml2js is to use npm, just npm install xml2js which will download xml2js and all dependencies.

xml2js is also available via Bower, just bower install xml2js which will download xml2js and all dependencies.

Usage

No extensive tutorials required because you are a smart developer! The task of parsing XML should be an easy one, so let's make it so! Here's some examples.

Shoot-and-forget usage

You want to parse XML as simple and easy as possible? It's dangerous to go alone, take this:

var parseString = require('xml2js').parseString;
var xml = "<root>Hello xml2js!</root>"
parseString(xml, function (err, result) {
    console.dir(result);
});

Can't get easier than this, right? This works starting with xml2js 0.2.3. With CoffeeScript it looks like this:

{parseString} = require 'xml2js'
xml = "<root>Hello xml2js!</root>"
parseString xml, (err, result) ->
    console.dir result

If you need some special options, fear not, xml2js supports a number of options (see below), you can specify these as second argument:

parseString(xml, {trim: true}, function (err, result) {
});

Simple as pie usage

That's right, if you have been using xml-simple or a home-grown wrapper, this was added in 0.1.11 just for you:

var fs = require('fs'),
    xml2js = require('xml2js');

var parser = new xml2js.Parser();
fs.readFile(__dirname + '/foo.xml', function(err, data) {
    parser.parseString(data, function (err, result) {
        console.dir(result);
        console.log('Done');
    });
});

Look ma, no event listeners!

You can also use xml2js from CoffeeScript, further reducing the clutter:

fs = require 'fs',
xml2js = require 'xml2js'

parser = new xml2js.Parser()
fs.readFile __dirname + '/foo.xml', (err, data) ->
  parser.parseString data, (err, result) ->
    console.dir result
    console.log 'Done.'

But what happens if you forget the new keyword to create a new Parser? In the middle of a nightly coding session, it might get lost, after all. Worry not, we got you covered! Starting with 0.2.8 you can also leave it out, in which case xml2js will helpfully add it for you, no bad surprises and inexplicable bugs!

Promise usage

var xml2js = require('xml2js');
var xml = '<foo></foo>';

// With parser
var parser = new xml2js.Parser(/* options */);
parser.parseStringPromise(xml).then(function (result) {
  console.dir(result);
  console.log('Done');
})
.catch(function (err) {
  // Failed
});

// Without parser
xml2js.parseStringPromise(xml /*, options */).then(function (result) {
  console.dir(result);
  console.log('Done');
})
.catch(function (err) {
  // Failed
});

Parsing multiple files

If you want to parse multiple files, you have multiple possibilities:

So you wanna some JSON?

Just wrap the result object in a call to JSON.stringify like this JSON.stringify(result). You get a string containing the JSON representation of the parsed object that you can feed to JSON-hungry consumers.

Displaying results

You might wonder why, using console.dir or console.log the output at some level is only [Object]. Don't worry, this is not because xml2js got lazy. That's because Node uses util.inspect to convert the object into strings and that function stops after depth=2 which is a bit low for most XML.

To display the whole deal, you can use console.log(util.inspect(result, false, null)), which displays the whole result.

So much for that, but what if you use eyes for nice colored output and it truncates the output with …? Don't fear, there's also a solution for that, you just need to increase the maxLength limit by creating a custom inspector var inspect = require('eyes').inspector({maxLength: false}) and then you can easily inspect(result).

XML builder usage

Since 0.4.0, objects can be also be used to build XML:

var xml2js = require('xml2js');

var obj = {name: "Super", Surname: "Man", age: 23};

var builder = new xml2js.Builder();
var xml = builder.buildObject(obj);

will result in:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<root>
  <name>Super</name>
  <Surname>Man</Surname>
  <age>23</age>
</root>

At the moment, a one to one bi-directional conversion is guaranteed only for default configuration, except for attrkey, charkey and explicitArray options you can redefine to your taste. Writing CDATA is supported via setting the cdata option to true.

To specify attributes:

var xml2js = require('xml2js');

var obj = {root: {$: {id: "my id"}, _: "my inner text"}};

var builder = new xml2js.Builder();
var xml = builder.buildObject(obj);

will result in:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<root id="my id">my inner text</root>

Adding xmlns attributes

You can generate XML that declares XML namespace prefix / URI pairs with xmlns attributes.

Example declaring a default namespace on the root element:

let obj = { 
  Foo: {
    $: {
      "xmlns": "http://foo.com"
    }   
  }
};

Result of buildObject(obj):

<Foo xmlns="http://foo.com"/>

Example declaring non-default namespaces on non-root elements:

let obj = {
  'foo:Foo': {
    $: {
      'xmlns:foo': 'http://foo.com'
    },
    'bar:Bar': {
      $: {
        'xmlns:bar': 'http://bar.com'
      }
    }
  }
}

Result of buildObject(obj):

<foo:Foo xmlns:foo="http://foo.com">
  <bar:Bar xmlns:bar="http://bar.com"/>
</foo:Foo>

Processing attribute, tag names and values

Since 0.4.1 you can optionally provide the parser with attribute name and tag name processors as well as element value processors (Since 0.4.14, you can also optionally provide the parser with attribute value processors):


function nameToUpperCase(name){
    return name.toUpperCase();
}

//transform all attribute and tag names and values to uppercase
parseString(xml, {
  tagNameProcessors: [nameToUpperCase],
  attrNameProcessors: [nameToUpperCase],
  valueProcessors: [nameToUpperCase],
  attrValueProcessors: [nameToUpperCase]},
  function (err, result) {
    // processed data
});

The tagNameProcessors and attrNameProcessors options accept an Array of functions with the following signature:

function (name){
  //do something with `name`
  return name
}

The attrValueProcessors and valueProcessors options accept an Array of functions with the following signature:

function (value, name) {
  //`name` will be the node name or attribute name
  //do something with `value`, (optionally) dependent on the node/attr name
  return value
}

Some processors are provided out-of-the-box and can be found in lib/processors.js:

Options

Apart from the default settings, there are a number of options that can be specified for the parser. Options are specified by new Parser({optionName: value}). Possible options are:

Options for the Builder class

These options are specified by new Builder({optionName: value}). Possible options are:

renderOpts, xmldec,doctype and headless pass through to xmlbuilder-js.

Updating to new version

Version 0.2 changed the default parsing settings, but version 0.1.14 introduced the default settings for version 0.2, so these settings can be tried before the migration.

var xml2js = require('xml2js');
var parser = new xml2js.Parser(xml2js.defaults["0.2"]);

To get the 0.1 defaults in version 0.2 you can just use xml2js.defaults["0.1"] in the same place. This provides you with enough time to migrate to the saner way of parsing in xml2js 0.2. We try to make the migration as simple and gentle as possible, but some breakage cannot be avoided.

So, what exactly did change and why? In 0.2 we changed some defaults to parse the XML in a more universal and sane way. So we disabled normalize and trim so xml2js does not cut out any text content. You can reenable this at will of course. A more important change is that we return the root tag in the resulting JavaScript structure via the explicitRoot setting, so you need to access the first element. This is useful for anybody who wants to know what the root node is and preserves more information. The last major change was to enable explicitArray, so everytime it is possible that one might embed more than one sub-tag into a tag, xml2js >= 0.2 returns an array even if the array just includes one element. This is useful when dealing with APIs that return variable amounts of subtags.

Running tests, development

Build Status Coverage Status Dependency Status

The development requirements are handled by npm, you just need to install them. We also have a number of unit tests, they can be run using npm test directly from the project root. This runs zap to discover all the tests and execute them.

If you like to contribute, keep in mind that xml2js is written in CoffeeScript, so don't develop on the JavaScript files that are checked into the repository for convenience reasons. Also, please write some unit test to check your behaviour and if it is some user-facing thing, add some documentation to this README, so people will know it exists. Thanks in advance!

Getting support

Please, if you have a problem with the library, first make sure you read this README. If you read this far, thanks, you're good. Then, please make sure your problem really is with xml2js. It is? Okay, then I'll look at it. Send me a mail and we can talk. Please don't open issues, as I don't think that is the proper forum for support problems. Some problems might as well really be bugs in xml2js, if so I'll let you know to open an issue instead :)

But if you know you really found a bug, feel free to open an issue instead.