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Resolving values

In an Asgard workflow, a setting's value can be resolved three ways: Literal, Expression and Template.

The three ways​

Literal​

Fixed content.

Example:

Welcome to our service!

Expression​

A JavaScript expression, for computation and logic.

Examples:

// read a variable directly
prevMessage

// read with a boolean expression
userName || 'guest'

// call a built-in function and use its return value
history(0, -1)

// call a built-in function and use its return value
urlEncode(searchKeyword)

Template​

Rendered with Handlebars syntax.

Example:

{{#each prevBlobs}}
  File
  {{@index}}:
  {{fileName}}
  {{#if (eq fileType 'IMAGE')}}
    Image file: {{mime}}
  {{/if}}
{{/each}}

What is built in​

Built-in variables​

  • Conversation: prevMessage, prevBlobs, prevPayload, prevError
  • Channel: customChannelId, customMessageId

See Expression variables for the details.

Built-in functions​

Eight functions are provided:

  • Conversation history: history(), historySize()
  • Data handling: urlEncode(), vecToStr(), xpathExtract()
  • Date and time: isoNow(), isoToday()

See Expression built-in functions for the details.

Examples​

Expression mode​

// using a variable
prevMessage || 'no message'

// a conditional
prevError ? `Error: ${prevError}` : 'processed normally'

// calling a function
`Conversation length: ${historySize()} messages`

Template mode​

{{#if prevMessage}}
  You just said: {{prevMessage}}
{{else}}
  Welcome, let's begin!
{{/if}}

The time now: {{{isoNow 'Asia/Taipei'}}}