JsonPath

Crystal conversion of the Javascript JSONPath from http://goessner.net/articles/JsonPath/

Installation

Add this to your application's shard.yml:

dependencies:
  json_path:
    github: lribeiro/json_path.cr

Usage

require "json_path"
require "json"

json = JSON.parse("{\"store\": {\"book\":[{\"category\": \"reference\"}]}}")

jp = JsonPath.new("$.store.book.*")
jp.on(json)

results in

	[{"category" => "reference"}] #	Array(JSON::Any)

Examples

 { "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
        }
      } ,
      "expensive": 10
    }

$.store.book[*].author can get the authors of all books in the store

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

$..author can get all authors

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

$.store.* can get all things in store, which are some books and a red bicycle

[
      {
         "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
      }
   ],
   {
      "color" : "red",
      "price" : 19.95
   }
]

$.store..price can get the price of everything in the store

[ 8.95, 12.99, 8.99, 22.99, 19.95 ]

$..book[2] can get the third book

[ 
  {
      "category" : "fiction",
      "author"   : "Herman Melville",
      "title"    : "Moby Dick",
      "isbn"     : "0-553-21311-3",
      "price"    :  8.99
   }
]

$..book[(@.length-1)] can get the last element

[{
  "category" : "fiction",
  "author" : "J. R. R. Tolkien",
  "title" : "The Lord of the Rings",
  "isbn" : "0-395-19395-8",
  "price" : 22.99
}]

$..book[-1:] can get the last book in order

[{
  "category" : "fiction",
  "author" : "J. R. R. Tolkien",
  "title" : "The Lord of the Rings",
  "isbn" : "0-395-19395-8",
  "price" : 22.99
}]

$..book[0,1] can get the first two books

[{
  "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
}]

$..book[:2] can get the first two books

[{
    "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
  }]

$..book[?(@.isbn)] can filter all books with isbn number

[{
        "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
     }]

$..book[?(@.price<10)] can filter all books cheapier than 10

[
  {
    "category" : "reference",
    "author" : "Nigel Rees",
    "title" : "Sayings of the Century",
    "price" : 8.95
  },
  {
    "category" : "fiction",
    "author" : "Herman Melville",
    "title" : "Moby Dick",
    "isbn" : "0-553-21311-3",
    "price" : 8.99
  }
]

$..* can get All members of JSON structure

[
{
  "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
  }
},
10,
[
  {
    "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
  }
],
{
  "color" : "red",
  "price" : 19.95
},
{
  "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
},
"reference",
"Nigel Rees",
"Sayings of the Century",
8.95,
"fiction",
"Evelyn Waugh",
"Sword of Honour",
12.99,
"fiction",
"Herman Melville",
"Moby Dick",
"0-553-21311-3",
8.99,
"fiction",
"J. R. R. Tolkien",
"The Lord of the Rings",
"0-395-19395-8",
22.99,
"red",
19.95
]

License

The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the JsonPath project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.