142 lines
4.4 KiB
Markdown
142 lines
4.4 KiB
Markdown
node-elementtree
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====================
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node-elementtree is a [Node.js](http://nodejs.org) XML parser and serializer based upon the [Python ElementTree v1.3](http://effbot.org/zone/element-index.htm) module.
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Installation
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====================
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$ npm install elementtree
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Using the library
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====================
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For the usage refer to the Python ElementTree library documentation - [http://effbot.org/zone/element-index.htm#usage](http://effbot.org/zone/element-index.htm#usage).
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Supported XPath expressions in `find`, `findall` and `findtext` methods are listed on [http://effbot.org/zone/element-xpath.htm](http://effbot.org/zone/element-xpath.htm).
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Example 1 – Creating An XML Document
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====================
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This example shows how to build a valid XML document that can be published to
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Atom Hopper. Atom Hopper is used internally as a bridge from products all the
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way to collecting revenue, called “Usage.” MaaS and other products send similar
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events to it every time user performs an action on a resource
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(e.g. creates,updates or deletes). Below is an example of leveraging the API
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to create a new XML document.
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```javascript
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var et = require('elementtree');
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var XML = et.XML;
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var ElementTree = et.ElementTree;
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var element = et.Element;
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var subElement = et.SubElement;
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var date, root, tenantId, serviceName, eventType, usageId, dataCenter, region,
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checks, resourceId, category, startTime, resourceName, etree, xml;
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date = new Date();
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root = element('entry');
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root.set('xmlns', 'http://www.w3.org/2005/Atom');
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tenantId = subElement(root, 'TenantId');
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tenantId.text = '12345';
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serviceName = subElement(root, 'ServiceName');
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serviceName.text = 'MaaS';
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resourceId = subElement(root, 'ResourceID');
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resourceId.text = 'enAAAA';
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usageId = subElement(root, 'UsageID');
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usageId.text = '550e8400-e29b-41d4-a716-446655440000';
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eventType = subElement(root, 'EventType');
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eventType.text = 'create';
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category = subElement(root, 'category');
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category.set('term', 'monitoring.entity.create');
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dataCenter = subElement(root, 'DataCenter');
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dataCenter.text = 'global';
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region = subElement(root, 'Region');
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region.text = 'global';
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startTime = subElement(root, 'StartTime');
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startTime.text = date;
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resourceName = subElement(root, 'ResourceName');
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resourceName.text = 'entity';
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etree = new ElementTree(root);
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xml = etree.write({'xml_declaration': false});
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console.log(xml);
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```
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As you can see, both et.Element and et.SubElement are factory methods which
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return a new instance of Element and SubElement class, respectively.
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When you create a new element (tag) you can use set method to set an attribute.
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To set the tag value, assign a value to the .text attribute.
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This example would output a document that looks like this:
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```xml
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<entry xmlns="http://www.w3.org/2005/Atom">
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<TenantId>12345</TenantId>
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<ServiceName>MaaS</ServiceName>
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<ResourceID>enAAAA</ResourceID>
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<UsageID>550e8400-e29b-41d4-a716-446655440000</UsageID>
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<EventType>create</EventType>
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<category term="monitoring.entity.create"/>
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<DataCenter>global</DataCenter>
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<Region>global</Region>
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<StartTime>Sun Apr 29 2012 16:37:32 GMT-0700 (PDT)</StartTime>
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<ResourceName>entity</ResourceName>
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</entry>
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```
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Example 2 – Parsing An XML Document
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====================
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This example shows how to parse an XML document and use simple XPath selectors.
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For demonstration purposes, we will use the XML document located at
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https://gist.github.com/2554343.
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Behind the scenes, node-elementtree uses Isaac’s sax library for parsing XML,
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but the library has a concept of “parsers,” which means it’s pretty simple to
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add support for a different parser.
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```javascript
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var fs = require('fs');
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var et = require('elementtree');
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var XML = et.XML;
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var ElementTree = et.ElementTree;
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var element = et.Element;
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var subElement = et.SubElement;
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var data, etree;
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data = fs.readFileSync('document.xml').toString();
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etree = et.parse(data);
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console.log(etree.findall('./entry/TenantId').length); // 2
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console.log(etree.findtext('./entry/ServiceName')); // MaaS
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console.log(etree.findall('./entry/category')[0].get('term')); // monitoring.entity.create
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console.log(etree.findall('*/category/[@term="monitoring.entity.update"]').length); // 1
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```
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Build status
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====================
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[](http://travis-ci.org/racker/node-elementtree)
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License
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====================
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node-elementtree is distributed under the [Apache license](http://www.apache.org/licenses/LICENSE-2.0.html).
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