Variable Component Advanced Usage

The Variable Component allows you to define Velocity Templates (VTL) to include logic for variable assignment. This feature enhances the flexibility and power of variable manipulation in your Flows.

For details on VTL syntax and usage, see the Velocity User Guide.

Advanced usage scenarios for the Variable Component are shown below, demonstrating how to leverage VTL for common tasks such as concatenating array values and incrementing counters.

Concatenating Values from an Array

To transform an array of values from an API response and pass them to an Assistant or Agent in another variable, you can create a new variable using a VTL script. This script generates plain text content to send to the Assistant.

Sample

Suppose you have a variable named {items}, mapped from an API response with the following content:

  {
    "name": "John",
    "age": 23
  },
  {
    "name": "Jane",
    "age": 23
  }

To create a new variable {userNames} that contains a comma-separated list of names, use the following VTL script:

#foreach( $item in {items} )
    $item.name#if( $foreach.hasNext ), #end
#end

This script will assign the following value to {userNames}:

John, Jane

Incrementing a Counter

To increment the value of a Number variable, use the following script:

#set( {count} = {count} + 1)
{count}

To cast a String value to an Integer, use this script:

#set( {count} = $number.toNumber({count}) + 1)
{count}

Date and Time

The Variable Component also supports working with date and time using built-in date utilities.

To set the current date in a variable using the default format for the current locale:

$date

To apply a custom format (e.g., ISO format):

$date.format("yyyy-MM-dd", $date.getDate())

You can also build date-based phrases to send to an Assistant or Agent. For example, the following script calculates the date 7 days ago and today's date, then formats both:

## Get the calendar
#set( $calendar = $date.getCalendar() )
## Subtract 7 days. The number 5 corresponds to java.util.Calendar.DAY_OF_MONTH
#evaluate( $calendar.add(5, -7) )
#set( $startTime = $date.format("yyyy-MM-dd", $calendar.getTime()) )
#set( $currentTime = $date.format("yyyy-MM-dd", $date.getDate()) )

Show me the news from $startTime till $currentTime

To change the time zone, you need to set the timezone variable with a valid time zone value such as "UTC", "GMT-3", or "GMT+5".