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jsonpath

A command-line tool for manipulating JSON using JSONPath.

Getting Started

Usage

Applying a JSONPath query on a file

% jsonpath '$.store.book[*].author' sample.json -p

[
    "Nigel Rees",
    "Evelyn Waugh",
    "Herman Melville",
    "J. R. R. Tolkien"
]

Viewing path to matching results

% jsonpath '$.store.book[*].author' sample.json -lp
[
    "$['store']['book'][0]['author']",
    "$['store']['book'][1]['author']",
    "$['store']['book'][2]['author']",
    "$['store']['book'][3]['author']"
]

Getting help with arguments and options

% jsonpath help simple

OVERVIEW: Simplified interface to quickly run a JSONPath query against a file

USAGE: jsonpath simple <query> <input> [-l] [-p]

ARGUMENTS:
  <query>                 JSONPath query
  <input>                 input file

OPTIONS:
  -l                      Output the path to the results instead of the results
                          themselves
  -p                      Pretty print the result JSON
  -h, --help              Show help information.

Installation

Mint

mint install KittyMac/jsonpath

What is JSONPath

The original Stefan Goessner JsonPath implemenentation was released in 2007, and from it spawned dozens of different implementations. This JSONPath Comparison chart shows the wide array of available implemenations, and at the time of this writing a Swift implementation is not present (note that there exists the SwiftPath project, but it is not included in said chart due to critical errors when running on Linux.

The rest of this section is largely adapted from the Jayway JsonPath Getting Started section.

Operators

Operator Description
$ The root element to query. This starts all path expressions.
@ The current node being processed by a filter predicate.
* Wildcard. Available anywhere a name or numeric are required.
.. Deep scan. Available anywhere a name is required.
.<name> Dot-notated child
['<name>' (, '<name>')] Bracket-notated child or children
[<number> (, <number>)] Array index or indexes
[start:end] Array slice operator
[?(<expression>)] Filter expression. Expression must evaluate to a boolean value.

Functions

Functions can be invoked at the tail end of a path - the input to a function is the output of the path expression. The function output is dictated by the function itself.

Function Description Output type
min() Provides the min value of an array of numbers Double
max() Provides the max value of an array of numbers Double
avg() Provides the average value of an array of numbers Double
stddev() Provides the standard deviation value of an array of numbers Double
length() Provides the length of an array Integer
sum() Provides the sum value of an array of numbers Double
keys() Provides the property keys (An alternative for terminal tilde ~) Set<E>
concat(X) Provides a concatinated version of the path output with a new item like input
append(X) add an item to the json path output array like input

Filter Operators

Filters are logical expressions used to filter arrays. A typical filter would be [?(@.age > 18)] where @ represents the current item being processed. More complex filters can be created with logical operators && and ||. String literals must be enclosed by single or double quotes ([?(@.color == 'blue')] or [?(@.color == "blue")]).

Operator Description
== left is equal to right (note that 1 is not equal to '1')
!= left is not equal to right
< left is less than right
<= left is less or equal to right
> left is greater than right
>= left is greater than or equal to right
=~ left matches regular expression [?(@.name =~ /foo.*?/i)]
in left exists in right [?(@.size in ['S', 'M'])]
nin left does not exists in right
subsetof left is a subset of right [?(@.sizes subsetof ['S', 'M', 'L'])]
anyof left has an intersection with right [?(@.sizes anyof ['M', 'L'])]
noneof left has no intersection with right [?(@.sizes noneof ['M', 'L'])]
size size of left (array or string) should match right
empty left (array or string) should be empty

Path Examples

Given the json

{
  "store": {
    "book": [
      {
        "category": "reference",
        "author": "Nigel Rees",
        "title": "Sayings of the Century",
        "display-price": 8.95,
        "bargain": true
      },
      {
        "category": "fiction",
        "author": "Evelyn Waugh",
        "title": "Sword of Honour",
        "display-price": 12.99,
        "bargain": false
      },
      {
        "category": "fiction",
        "author": "Herman Melville",
        "title": "Moby Dick",
        "isbn": "0-553-21311-3",
        "display-price": 8.99,
        "bargain": true
      },
      {
        "category": "fiction",
        "author": "J. R. R. Tolkien",
        "title": "The Lord of the Rings",
        "isbn": "0-395-19395-8",
        "display-price": 22.99,
        "bargain": false
      }
    ],
    "bicycle": {
      "color": "red",
      "display-price": 19.95,
      "foo:bar": "fooBar",
      "dot.notation": "new",
      "dash-notation": "dashes"
    }
  }
}
JsonPath (click link to try) Result
$.store.book[*].author The authors of all books
$..['author','title'] All authors and titles
$.store.* All things, both books and bicycles
$.store..display-price The price of everything
$..book[2] The third book
$..book[-2] The second to last book
$..book[0,1] The first two books
$..book[:2] All books from index 0 (inclusive) until index 2 (exclusive)
$..book[1:2] All books from index 1 (inclusive) until index 2 (exclusive)
$..book[-2:] Last two books
$..book[2:] Book number two from tail
$..book[?(@.isbn)] All books with an ISBN number
$.store.book[?(@.display-price < 10)] All books in store cheaper than 10
$..book[?(@.bargain == true)] All bargain books in store
$..book[?(@.author =~ /.*REES/i)] All books matching regex (ignore case)
$..* Give me every thing
$..book.length() The number of books