xpath-evaluator-app

NodeJS app to evaluate ODK XPath expressions using Enketo's XPath evaluator.

Prerequisites

Not sure which versions of Node are compatible yet. It's just an MVP at this stage. It was built and tested on Node v8 and should work on later versions as well.

Install (using git)

1. Clone the repo (or copy the files)
2. Run npm install --production from the installation folder
3. Run npm link from the installation folder. This will make the xpath-evaluate command available globally on your machine.

(If this app is deemed useful it will be published on npm, and installation will become easier).

Uninstall

1. To remove the links, run npm unlink and remove the xpath-evaluator-app folder.

Use

The application has a single required XPath expression parameter and 2 options that can be provided using flags:

1. --xml: path to an XML file
2. --context: the context path in which the XPath expression should be evaluated

Run it via the command line as shown below under Examples.

Errors are returned to stderr and the XPath evaluation result as string is return to stdout.

Help

xpath-evaluate --help

Examples

You can try these out from the app's folder. The XML documents used for the sample results of these expressions are at test/xml.

• xpath-evaluate 1+1 👉 2
• xpath-evaluate "1 + 1" 👉 2 (spaces in expression requires use of quotation marks)
• xpath-evaluate "pad2('1')" 👉 01
• xpath-evaluate "/data/a" --xml test/xml/one.xml 👉 a
• xpath-evaluate "pad2( /data/a )" --xml test/xml/one.xml 👉 0a
• xpath-evaluate "count-selected( /data/a )" --xml test/xml/one.xml 👉 1
• xpath-evaluate "../a" --xml test/xml/one.xml --context "/data/b" 👉 a
• xpath-evaluate "/data/odk:b" --xml test/xml/namespaces.xml 👉 b
• xpath-evaluate "//*[@id='2']" --xml test/xml/one.xml 👉 b
• xpath-evaluate "//*[@id='2']/@id" --xml test/xml/one.xml 👉 2
• xpath-evaluate "//*[@CapiTalized='true']" --xml test/xml/one.xml: 👉 b