JSON JSONPath

One of the biggest strengths of XML is XPath, the query-oriented language to query subsections of an XML document. In the same line, JSONPath is a query language with features similar to XPath that lets you extract just the bits of a JSON document your application needs.

To use JSONPath, you will need to include its dependency and then use it.

JSONPath Syntax

As XPath, JSONPath also has syntax to follow:

• $ – symbol refers to the root object or element.
• @ – symbol refers to the current object or element.
• . – operator is the dot-child operator, which you use to denote a child element of the current element.
• [ ] – is the subscript operator, which you use to denote a child element of the current element (by name or index).
• * – operator is a wildcard, returning all objects or elements regardless of their names.
• , – operator is the union operator, which returns the union of the children or indexes indicated.
• : – operator is the array slice operator, so you can slice collections using the syntax [start:end:step] to return a subcollection of a collection.
• ( ) – operator lets you pass a script expression in the underlying implementation’s script language. It’s not supported by every implementation of JSONPath, however.
• ? ( ) – to query all items that meet a certain criteria.

e.g.

$.store.book[0].title
$.store.book[*].title
$..book[3]

//or using brackets

$['store']['book'][0].['title']
$['store']['book'][*].['title']
$..['book'][3]

$.store.book[?(@.price < 10)].title

JSONPath Example

Let’s assume we have given JSON object and we want to apply JSONPath on it.

{ "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
    }
  }
}

Let’s apply some JSONPaths to above JSON object.

Example 1

var response = jsonPath(store , "$..author").toJSONString();

//Outpout:

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

Example 2

var response = jsonPath(store , "$..book[3]").toJSONString();

//Outpout:

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

Live Example : Learn to build JSONPath expressions in line editor

JSONPath dependencies

<dependency>
	<groupId>com.jayway.jsonpath</groupId>
	<artifactId>json-path</artifactId>
	<version>2.0.0</version>
</dependency>

Reference: JSONPath – XPath for JSON