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Overview

Use a 

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 when it is neccessary necessary to repeat an action or set of actions multiple times. 

There are three types of supported looping:

  1. Polling, repeating the same operation multiple times with the same parameters until a desired result is obtained and then generating a single output record. Output results are only generated at the end of the iterations. For example, polling an HTTP API until the results are available.

  2. Accumulation, repeating the same operation multiple times, where each iteration accumulates the progress results and triggers the next iteration with the updated result. Generates a single output record. For example, calling the DB to get the parent record, and repeating with the parent until the root has been reached.

  3. Paging, repeating an operation multiple times with different parameters and generating the next parameters with a set of output records for each iteration of the loop. For example, reading from a paging API, where each iteration gives you the link for the next iteration

,

  1. and a set of output records.

For a worked example, see Loop Action Configuration.

Start Loop and End Loop

Loops consist of a

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property

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Basic Settings

FieldDescriptionExample ValueNameName given to the action node. This will be displayed on the actionflow canvas.MyJSONReaderInput 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 an HTTP Action or the body from an API request.

// consist of the name of the pipe 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 node items.

It can be used to specify which nodes are extracted from the JSON.

// JSON Path

$.main_page.title

Input Connection Points

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

To add a new input connection point

  and an 

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joined by a loop connector which returns the result of the End Node to the Start Node. Each part of the Loop has its own set of properties described below.

The key concept of a loop is that the attributes passed into it are available as passthrough as well as attributes mapped in from the End Loop. This allows the original passthrough values to be referenced and if the loop is manipulating the incoming attributes, for example incrementing a number, this is also available. The mapped attributes that are manipulated by the loop are shown with a loop icon, passthrough attributes will be shown with the icon of where they have come from, for example a calculated action.

Tip

Loops wait until all their internal nodes have completed their tasks before beginning the next iteration of a loop.


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 -  Start Loop

Basic Settings

FieldDescriptionExample Value
NameThe name given to the node and displayed on the canvas.My Loop
End Loop Action

A read-only field that states the end loop node associated with the start loop node.

// The End Loop Node will initially take the name of the Start Loop // Node and prefix it with "end".

End My Loop

Output Attributes

The grid contains a list of all Output Attributes.

  • To add an Output Attribute, in the section toolbar click 
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     to open a new input connection point and  and set its properties; see Input Connection Points.
  • To edit an existing input connection point Output Attribute, double-click it in the list to open its properties.
  • To remove an input connection point Output Attribute, select one (or more) from the list and in the section toolbar click 
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 -  End Loop

Basic Settings

FieldDescriptionExample Value
NameThe name given to the node and displayed on the canvas. The name will default to the Start Loop name prefixed with end.End My Loop
Records to outputSets whether to output all records from the loop or just the final record.

Output Connection Points

This section has a toolbar with standard buttons. 
All Records or Final Record
Output Mode

A read-only field that states the end loop node associated with the start loop node.

// The End Loop Node will initially take the name of the Start Loop // Node and prefix it with "end".

End My Loop

Until ExpressionAn expression that is checked on each cycle of the loop, and once the expression returns true the loop will end.  

// Where myValue is being sent into the End Loop Node on a pipe // called in.

in.myValue == 10

Max LoopsThis is a safety net designed to stop infinite loops. The number entered here will stop 

//Defaults to 10000

10000

Input Parameters

Can accept a single

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

  • To add a new output pathan Input Parameter, in the section toolbar click 
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     to open a new output path and set the expression; see Output Connection Points and set its properties.
  • To edit an existing output pathInput Parameter, double-click it in the list to open its properties.
  • To remove an output pathInput Parameter, select one (or more) from the list and in the section toolbar click 
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    .

Output Attributes

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

Worked Example

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

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// 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.name, returns 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.initials, an array of data is returned. See Array Handling Functions.
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titleNote the use of
  • ^ traverses up the hierarchy 1 layer.
  • . tranverses down the heirach 1 layer.

Learn More

For links to all pages in this topic, see Understanding Actionflows

Input Parameters can be mapped to by clocking on the incoming connector.


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Learn More