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177 lines
6.4 KiB
Markdown
177 lines
6.4 KiB
Markdown
node-xml2js
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===========
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Ever had the urge to parse XML? And wanted to access the data in some sane,
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easy way? Don't want to compile a C parser, for whatever reason? Then xml2js is
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what you're looking for!
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Description
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===========
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Simple XML to JavaScript object converter. Uses
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[sax-js](https://github.com/isaacs/sax-js/).
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Note: If you're looking for a full DOM parser, you probably want
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[JSDom](https://github.com/tmpvar/jsdom).
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Installation
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============
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Simplest way to install `xml2js` is to use [npm](http://npmjs.org), just `npm
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install xml2js` which will download xml2js and all dependencies.
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Usage
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=====
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This will have to do, unless you're looking for some fancy extensive
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documentation. If you're looking for every single option and usage, see the
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unit tests.
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Simple as pie usage
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-------------------
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The simplest way to use it, is to use the optional callback interface added in
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0.1.11. That's right, if you have been using xml-simple or a home-grown
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wrapper, this is for you:
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```javascript
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var fs = require('fs'),
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xml2js = require('xml2js');
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var parser = new xml2js.Parser();
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fs.readFile(__dirname + '/foo.xml', function(err, data) {
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parser.parseString(data, function (err, result) {
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console.dir(result);
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console.log('Done');
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});
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});
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```
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Look ma, no event listeners! Alternatively you can still use the traditional
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`addListener` variant:
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```javascript
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var fs = require('fs'),
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xml2js = require('xml2js');
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var parser = new xml2js.Parser();
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parser.addListener('end', function(result) {
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console.dir(result);
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console.log('Done.');
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});
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fs.readFile(__dirname + '/foo.xml', function(err, data) {
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parser.parseString(data);
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});
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```
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You can also use xml2js from
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[CoffeeScript](http://jashkenas.github.com/coffee-script/), further reducing
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the clutter:
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```coffeescript
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fs = require 'fs',
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xml2js = require 'xml2js'
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parser = new xml2js.Parser()
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fs.readFile __dirname + '/foo.xml', (err, data) ->
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parser.parseString data, (err, result) ->
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console.dir result
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console.log 'Done.'
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```
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So you wanna some JSON?
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-----------------------
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Just wrap the `result` object in a call to `JSON.stringify` like this
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`JSON.stringify(result)`. You get a string containing the JSON representation
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of the parsed object that you can feed to JSON-hungry consumers.
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Displaying results
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------------------
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You might wonder why, using `console.dir` or `console.log` the output at some
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level is only `[Object]`. Don't worry, this is not because xml2js got lazy.
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That's because Node uses `util.inspect` to convert the object into strings and
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that function stops after `depth=2` which is a bit low for most XML.
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To display the whole deal, you can use `console.log(util.inspect(result, false,
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null))`, which displays the whole result.
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So much for that, but what if you use
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[eyes](https://github.com/cloudhead/eyes.js) for nice colored output and it
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truncates the output with `…`? Don't fear, there's also a solution for that,
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you just need to increase the `maxLength` limit by creating a custom inspector
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`var inspect = require('eyes').inspector({maxLength: false})` and then you can
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easily `inspect(result)`.
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Options
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=======
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Apart from the default settings, there is a number of options that can be
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specified for the parser. Options are specified by ``new Parser({optionName:
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value})``. Possible options are:
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* `attrkey` (default: `$`): Prefix that is used to access the attributes.
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Version 0.1 default was `@`.
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* `charkey` (default: `_`): Prefix that is used to access the character
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content. Version 0.1 default was `#`.
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* `explicitCharkey` (default: `false`)
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* `trim` (default: `false`): Trim the whitespace at the beginning and end of
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text nodes.
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* `normalizeTags` (default: `false`): Normalize all tag names to lowercase.
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* `normalize` (default: `false`): Trim whitespaces inside text nodes.
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* `explicitRoot` (default: `true`): Set this if you want to get the root
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node in the resulting object.
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* `emptyTag` (default: `undefined`): what will the value of empty nodes be.
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Default is `{}`.
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* `explicitArray` (default: `true`): Always put child nodes in an array if
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true; otherwise an array is created only if there is more than one.
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* `ignoreAttrs` (default: `false`): Ignore all XML attributes and only create
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text nodes.
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* `mergeAttrs` (default: `false`): Merge attributes and child elements as
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properties of the parent, instead of keying attributes off a child
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attribute object. This option is ignored if `ignoreAttrs` is `false`.
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* `validator` (default `null`): You can specify a callable that validates
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the resulting structure somehow, however you want. See unit tests
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for an example.
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* `xmlns` (default `false`): Give each element a field usually called '$ns'
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(the first character is the same as attrkey) that contains its local name
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and namespace URI.
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Updating to new version
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=======================
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Version 0.2 changed the default parsing settings, but version 0.1.14 introduced
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the default settings for version 0.2, so these settings can be tried before the
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migration.
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```javascript
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var xml2js = require('xml2js');
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var parser = new xml2js.Parser(xml2js.defaults["0.2"]);
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```
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To get the 0.1 defaults in version 0.2 you can just use
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`xml2js.defaults["0.1"]` in the same place. This provides you with enough time
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to migrate to the saner way of parsing in xml2js 0.2. We try to make the
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migration as simple and gentle as possible, but some breakage cannot be
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avoided.
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So, what exactly did change and why? In 0.2 we changed some defaults to parse
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the XML in a more universal and sane way. So we disabled `normalize` and `trim`
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so xml2js does not cut out any text content. You can reenable this at will of
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course. A more important change is that we return the root tag in the resulting
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JavaScript structure via the `explicitRoot` setting, so you need to access the
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first element. This is useful for anybody who wants to know what the root node
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is and preserves more information. The last major change was to enable
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`explicitArray`, so everytime it is possible that one might embed more than one
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sub-tag into a tag, xml2js >= 0.2 returns an array even if the array just
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includes one element. This is useful when dealing with APIs that return
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variable amounts of subtags.
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Running tests, development
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==========================
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The development requirements are handled by npm, you just need to install
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them. We also have a number of unit tests, they can be run using `zap`
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directly from the project root.
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