openrosa-xpath-evaluator

Openrosa XForms Evaluator

Wrapper for browsers' XPath evaluator with added support for OpenRosa extensions.

For more info on extended XPath expressions/bindings supported by XForms/OpenRosa/OpenDataKit (ODK) see:

• ODK XForm Specification
• OpenDataKit Binding documentation
• JavaRosa XPath functions

Limitations

Any expression made requesting a node-type result will be delegated to the underlying xpath evaluator.

Also, the expression parser is currently very basic and will fail for some xpath expressions. Some examples of expressions that are and are not supported follow.

Supported XPath expressions:

• /model/instance[1]//*
• /model/instance[1]/*/meta/*
• ./author
• author
• first.name
• /bookstore
• //author
• author/first-name
• bookstore//title
• bookstore/*/title
• bookstore//book/excerpt//emph
• .//title
• author/*
• book/*/last-name
• @style
• price/@exchange
• price/@exchange/total
• book[@style]
• book/@style
• ./first-name
• first-name
• author[1]
• author[first-name][3]
• my:book
• x/y[1]
• x[1]/y[2]
• book[excerpt]
• book[excerpt]/title
• book[excerpt]/author[degree]
• book[author/degree]
• author[degree][award]
• ancestor::book[1]
• ancestor::book[author][1]
• ancestor::author[parent::book][1]

Unsupported XPath expressions:

• */*
• *[@specialty]
• @my:*
• @*
• author[degree and award]
• author[(degree or award) and publication]
• author[degree and not(publication)]
• author[not(degree or award) and publication]
• author[. = "Matthew Bob"]
• author[last-name = "Bob" and ../price > 50]
• author[not(last-name = "Bob")]
• author[first-name = "Bob"]
• author[last-name = "Bob" and first-name = "Joe"]
• author[* = "Bob"]
• author[last-name = "Bob"]
• author[last-name[1] = "Bob"]
• author[last-name [position()=1]= "Bob"]
• book[last()]
• book/author[last()]
• book[position() <= 3]
• book[/bookstore/@specialty=@style]
• degree[position() < 3]
• degree[@from != "Harvard"]
• my:*
• p/text()[2]
• price[@intl = "Canada"]
• x/y[position() = 1]
• (book/author)[last()]
• (x/y)[1]