JSONPath

This is an implementation of JSONPath in Scala. The library follows the semantics describted by Stefan Goessner on his blog. Although, due to the lack of standardization, it is worth reading the following documentation.

Syntax

JSONPath expressions

In a JSONPath expression, the abstract name $ is used to designate to the outer level object.

JSONPath expressions can use the dot–notation $.store.book[0].title or the bracket–notation $['store']['book'][0]['title'].

Based on the following JSON document :

    { "store": {
        "book": [ 
          { "category": "reference",
            "author": "Nigel Rees",
            "title": "Sayings of the Century",
            "price": 8.95
          },
          { "category": "fiction",
            "author": "Evelyn Waugh",
            "title": "Sword of Honour",
            "price": 12.99
          },
          { "category": "fiction",
            "author": "Herman Melville",
            "title": "Moby Dick",
            "isbn": "0-553-21311-3",
            "price": 8.99
          },
          { "category": "fiction",
            "author": "J. R. R. Tolkien",
            "title": "The Lord of the Rings",
            "isbn": "0-395-19395-8",
            "price": 22.99
          }
        ],
        "bicycle": {
          "color": "red",
          "price": 19.95
        }
      }
    }

Here is a list of supported operators :

Operator	Description	Example
`$`	the root element	`$`
`@`	the current element	`@`
`.` or `[]`	the child element	`$.bicycle or $['bicycle']`
`..`	recursive descent	`$..author`
`*`	wildcard	`$.store.book[*].author`
`[,]`	collection of names or indices	`$[2,5], $.store.book['title', 'author']`
`[start:stop:end]`	array slice	`$[2:-3]`, `$[::-1]`
`[?(expression)]`	filter expression	`$.store.book[?(@.price < 10)].title`

Filter expressions

The underlying engine for writing filter expressions currently support two different kinds of filter expression:

Filter	Example
Has-child filter	`$.store.book[?(@.isbn)].title`
Comparison filter	`$.store.book[?(@.category == 'fiction')].title`

You can also combine them with boolean operators, eg: $.store.book[?(@.price < 10 && @.price >4)].title

Implementation

This implementation is JSON provider agnostic, but it requires to have JSON representation based on raw types from the JVM. For instance, with Jackson, one could do the following:

val jsonSample = (new ObjectMapper).readValue("""{"a":"A","b":"B"}""", classOf[Object])

JSONPath.query("$.a", jsonSample) gives you Right(non-empty iterator). This will allow you to iterate over all possible solutions to the query.

eg :

JsonPath.query("$.a", jsonSample).right.map(_.toVector)

gives you Right(Vector("A"))

Licence