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REFERENCE

Developer Reference

Authentication, APIs, SDKs, Flow Agent processors and parameter resolution, in full.

Handlebars in five minutes

Handlebars is the template engine behind Asgard's Template mode, letting you produce dynamic text with concise syntax.

  1. The basics​

    Handlebars inserts dynamic content with braces, and there are two forms:

    Double braces versus triple braces​

    Double braces {{}} — HTML escaped

    Hello {{name}}! Your order number is {{orderNumber}}

    Triple braces {{{}}} — not escaped

    Hello {{{name}}}! Your order number is {{{orderNumber}}}
    SyntaxPurposeHTML escapingExample
    {{}}Ordinary text output✅ escaped{{content}} → <script>
    {{{}}}Raw output❌ not escaped{{{content}}} → <script>

    What to use in Asgard​

    In Asgard, use triple braces {{{}}} in most cases, because:

    • It avoids unintended conversion: special characters are not mangled (< becoming &lt;, say)
    • It keeps data intact: the variable's content comes out as it went in
    Hello {{{name}}}! Your order number is {{{orderNumber}}}

    Output:

    Hello Alice! Your order number is ORD20240115001

    📖 Learning the syntax properly
    The full Handlebars syntax is in the official documentation

  2. Core syntax​

    Inserting a variable​

    Hello {{{user.name}}}! Your membership tier is {{{user.level}}}

    Conditionals​

    {{#if hasNewOrders}}
      You have
      {{{newOrderCount}}}
      new orders
    {{else}}
      No new orders right now
    {{/if}}

    Loops​

    • Products:
    {{#each products}}
      {{{@index}}}.
      {{{name}}}
      - NT$
      {{{price}}}
    {{/each}}

  3. Asgard's built-in helpers​

    Asgard provides eight helpers:

    {{{history 0 -1}}}
    <!-- conversation history -->
     
    {{{historySize}}}
    <!-- how many messages -->
     
    {{{toJson user}}}
    <!-- convert to JSON -->
     
    {{{urlEncode searchKeyword}}}
    <!-- URL encode -->
     
    {{{xpathExtract xmlData '/root/item'}}}
    <!-- XML lookup -->
     
    {{{vecToStr vector '[' ']' ','}}}
    <!-- vector to string -->
     
    {{{isoNow 'Asia/Taipei'}}}
    <!-- the time now -->
     
    {{{isoToday 'Asia/Taipei'}}}
    <!-- today's date -->

  4. Worked examples​

    A basic message template​

    Hello
    {{{user.name}}}! 
    System status: 
    • Messages: {{{historySize}}}
    • The time now: {{{isoNow 'Asia/Taipei'}}}
     
    {{#if hasUpdates}}
      Recent messages:
      {{{history -3 -1}}}
    {{/if}}

    A button template​

    {
      "type": "BUTTON",
      "title": "{{{user.name}}}'s details",
      "text": "Membership details:\n{{{toJson user}}}",
      "buttons": [
        {
          "label": "See the history",
          "action": {
            "type": "MESSAGE",
            "text": "Show the conversation history"
          }
        }
      ]
    }

    An API query​

    • Search: {{{urlEncode query}}}
    • Queried at: {{{isoNow 'Asia/Taipei'}}}
     
    {{#if xmlResponse}}
    • Results:
      {{{xpathExtract xmlResponse '//item/title'}}}
    {{/if}}

  5. Choosing between Template and Expression​

    SituationUseWhy
    Text templatesTemplateConcise syntax
    Complex computationExpressionThe whole of JavaScript
    ConditionalsTemplateBuilt in
    ArithmeticExpressionMore flexible

  6. Quick checklist​

    ✅ Insert a variable: {{{variable}}}
    ✅ Conditional: {{#if condition}}
    ✅ Loop: {{#each array}}
    ✅ Asgard helpers: eight of them
    ✅ Object properties: {{{user.name}}} for nested access

  7. Going further​

    Standard Handlebars syntax plus Asgard's helpers is enough to build capable dynamic message templates.

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