JPath is a Ruby library that allows to execute XPath queries on JSON documents.

JPath doesn't use any dependencies. Simply install via rubygems:

gem install jpath

or clone it from github:

git clone https://github.com/merimond/jpath.git

JPath is in early beta stage. So having an up-to-date Git version is more preferable.

Please note that JPath works with standard XPath syntax, not one of XPath alternatives, such as the great JSONPath syntax by Stefan Goessner. If you prefer the latter, there's a terrific library by Joshua Hull that you should check out.

Although JSON and XML are both data containers, they are quite different when it comes to searching and manipulating data. So JPath may behave somewhat differently from what you woud expect, although we tried to make some sensible assumptions while transforming the XML-oriented search paradigm into the JSON world.

JPath support all the basic and some of the more advanced XPath functions:

Simple chains with children and ancestors:

/store/book/author
//author
/store/*

Position predicates:

//book[last()]
//book[position()<3]

Attribute and child predicates:

//book[@price<10]
//book[isbn]

Multiple predicates:

//book[@price>10][last()]

And all of the above in non-abbreviated form:

/descendant::book
/child::book[attribute::price="8.95"]

Test files are a bit of a mess at the moment, but they should give you an indication of what's currently supported.

Fork, send pull requests, file bug reports -- any help is welcome.