JSON Node

JSON Node

Overview

Use a 

 action to process JSON data, and convert it into specific data objects that can be used by PhixFlow for processing. The JSON Node extracts one or more records from the provided JSON object using the JSON path specified.

Basic Settings

Expect literal values or expressions encapsulated within ${} syntax, for example ${in.MyValue}. A worked example of the JSON Node is provided at the end of this page.

Field

Description

Example Value

Name

Name given to the JSON Node. This will be displayed on the actionflow canvas.

MyJSONReader

Input Expression

The input expression provides the JSON data to be operated upon. Typically, this will be a simple expression pointing at an incoming attribute, such as, the body from a HTTP Node.

In PhixFlow version 11.1 onwards, this field is mandatory.

// Consists of the pipe name and the name of a mapped attribute

in.body

Use Strict JSON parsing

Defines the parsing of the JSON, disabled will be lenient and enabled will be strict.

Lenient parsing relaxes validation allowing the following to be present in the JSON data:

  • Use of single quotes, for example: {'name': 'Some “quotes” in a string'}

  • Unquoted field names, for example:  {name: “value”}

  • Unescaped control characters, including literal new lines to appear within a string.

  • Allow trailing commas {“name”: ”value”,}

// Leaving the default option

Disabled.

Path

The JSON Path expression is evaluated against the data provided by the Input Expression and returns a list of JSON elements. It determines which elements are extracted from the JSON.

The path starts at the root element represented by $ and each element in the path is separated by a full stop. The ^ traverses up a node and a . traverses down the node.

Note that the path determines the number of nodes that are processed, which directly correlates to the number of records returned by the JSON Node. For example, if the path returns the route element of the JSON only one record will be returned. Whereas a path that returns children nodes will return one record for each child element

// JSON Path

$.main_page.title

Input Connection Points

Can Accept a single

.

The grid contains a list of all input connection points and their type.

  • To add a new input connection point, in the section toolbar click 

     to open a new input connection point and set its properties; see Input Connection Points.

  • To edit an existing input connection point, double-click it in the list to open its properties.

  • To remove an input connection point, select one and in the section toolbar click 

    .

Output Connection Points

This section has a toolbar with standard buttonsThe grid contains a list of all output connection points.

  • To add a new output path, in the section toolbar click 

     to open a new output path and set the expression; see Output Connection Points.

  • To edit an existing output path, double-click it in the list to open its properties.

  • To remove an output path, select one and in the section toolbar click 

    .

Output Attributes

JSON is converted into data objects that can be used by PhixFlow, this information is accessed using the syntax, _result.AttributeName.

Advanced

Field

Description

Prioritise Throughput Over Ordering

Worked Example

Extracting Data

Below is an example JSON object passed to the JSON Node:

Example JSON
// Example JSON string. {     "main_page": {         "page": "PF Main Page",         "title": {             "name": "PF Title Text",             "data": [                 {"initials": "AA", "value" : "Alistair Andrews"},                 {"initials": "BB", "value" : "Bert Brown"}             ]         }     } }



JSON Path$.main_page.title

This path will bring back all elements matching the JSON path including the parent/grandparents and all child elements. The path defines the starting point from which we reference the JSON nodes.

The following examples show how to reference the returned JSON data:

  1. _result.namereturns PF Title Text

  2. _result.^.page, returns PF Main Page

    1. The ^ traverses up the JSON hierarchy. 

  3. listToString(_result.data.initials)returns "AA, BB"

    1. Because there are multiple JSON nodes under  _result.data.initialsan array of data is returned. See Array Handling Functions.

Note the use of

  • ^traverses up the hierarchy 1 layer.

  • . is the separator between nodes

  • using .. traverses down the hierarchy 1 layer.

Retrieving Field Names

Example JSON
{ "a": "1", "b": 2, "c": "xxx", "d": { "x": 1, "y": 2, "z": 3 } }

To retrieve the field names held in element d:

do( $json = jsonToItems(in.JsonIn), $fields = getFields($json.d), $fields[1] )

Returns the first field name of d which is “x”. See getFields.