3 JSONPath functionality

Overview

This section provides details of supported JSONPath functionality in item value preprocessing steps.

JSONPath consists of segments separated with dots. A segment can be either a simple word like a JSON value name, * or a more complex construct enclosed within square brackets [ ]. The separating dot before bracket segment is optional and can be omitted. For example:

See also: Escaping special characters from LLD macro values in JSONPath.

Supported segments

To find a matching segment ignoring its ancestry (detached segment) it must be prefixed with ‘..’ , for example $..name or $..['name'] return values of all ‘name’ properties.

Matched element names can be extracted by adding a ~ suffix to the JSONPath. It returns the name of the matched object or an index in string format of the matched array item. The output format follows the same rules as other JSONPath queries - definite path results are returned ‘as is’ and indefinite path results are returned in array. However there is not much point of extracting the name of an element matching a definite path - it’s already known.

Filter expression

Filter expression is a arithmetical expression in infix notation.

Supported operands:

Supported operators:

Functions

Functions can be used at the end of JSONPath. Multiple functions can be chained if the preceding function returns value that is accepted by the following function.

Supported functions:

Quoted numeric values are accepted by the JSONPath aggregate functions. It means that the values are converted from string type to numeric if aggregation is required.

Incompatible input will cause the function to generate error.

Output value

JSONPaths can be divided in definite and indefinite paths. A definite path can return only null or a single match. An indefinite path can return multiple matches, basically JSONPaths with detached, multiple name/index list, array slice or expression segments. However, when a function is used the JSONPath becomes definite, as functions always output single value.

A definite path returns the object/array/value it’s referencing, while indefinite path returns an array of the matched objects/arrays/values.

Whitespace

Whitespace (space, tab characters) can be freely used in bracket notation segments and expressions, for example, $[ 'a' ][ 0 ][ ?( $.b == 'c' ) ][ : -1 ].first( ).

Strings

Strings should be enclosed with single ‘ or double “ quotes. Inside the strings, single or double quotes (depending on which are used to enclose it) and backslashes \ are escaped with the backslash \ character.

Examples

Input data

{
  "books": [
    {
      "category": "reference",
      "author": "Nigel Rees",
      "title": "Sayings of the Century",
      "price": 8.95,
      "id": 1
    },
    {
      "category": "fiction",
      "author": "Evelyn Waugh",
      "title": "Sword of Honour",
      "price": 12.99,
      "id": 2
    },
    {
      "category": "fiction",
      "author": "Herman Melville",
      "title": "Moby Dick",
      "isbn": "0-553-21311-3",
      "price": 8.99,
      "id": 3
    },
    {
      "category": "fiction",
      "author": "J. R. R. Tolkien",
      "title": "The Lord of the Rings",
      "isbn": "0-395-19395-8",
      "price": 22.99,
      "id": 4
    }
  ],
  "services": {
    "delivery": {
      "servicegroup": 1000,
      "description": "Next day delivery in local town",
      "active": true,
      "price": 5
    },
    "bookbinding": {
      "servicegroup": 1001,
      "description": "Printing and assembling book in A5 format",
      "active": true,
      "price": 154.99
    },
    "restoration": {
      "servicegroup": 1002,
      "description": "Various restoration methods",
      "active": false,
      "methods": [
        {
          "description": "Checmical cleaning",
          "price": 46
        },
        {
          "description": "Pressing pages damaged by moisture",
          "price": 24.5
        },
        {
          "description": "Rebinding torn book",
          "price": 99.49
        }
      ]
    }
  },
  "filters": {
    "price": 10,
    "category": "fiction",
    "no filters": "no \"filters\""
  },
  "closed message": "Store is closed",
  "tags": [
    "a",
    "b",
    "c",
    "d",
    "e"
  ]
}