👨‍💻Template syntax

Overview

This article introduces the template syntax; by using variables and expressions, you can easily build the desired content and perform substitutions.

The template syntax can currently be applied to the following features:

• Certain message operations in conversation scripts.

• Parameters (Params) and callbacks in Webhook scripts.

Variable naming rules

Like most programming languages such as Python and JavaScript, conversation variables must follow the following rules:

1. Variable names must start with a letter (a-z, A-Z) or an underscore (_).

2. Subsequent characters can be letters, digits (0-9), or underscores (_).

3. Variable naming is case-sensitive; uppercase letters (A-Z) and lowercase letters (a-z) are considered different characters.

Here are some examples of variable names that comply with the naming rules:

• myVariable

• count

• first_name

• age123

Symbols and operators

Delimiters

The template syntax uses {{ ... }} and {% ... %} two kinds of symbol expressions. The former delimiter will be replaced with the actual string output in the content. As the syntax below shows, it will actually output “王小明，您好！” (Wang Xiaoming, hello!).

{{ name }}，您好！

You can also use a dot (.) to access deeper parts of a variable, for example

{{ contact.first_name }}

{# You can also access content using square brackets #}
{{ contact['first_name'] }}

And the latter {% ... %} delimiter is used for performing logical operations, such as for, if ... etc.

{# Set the variable name to Wang Xiaoming #}
{% set name = '王小明' %}

{# This will display 0,1,2,3 sequentially up to 10 #}
{% for i in range(0, 10) %}
    {{ i }}
{% endfor %}

Arithmetic operators

The template provides simple operators; others include the following

Operator	Syntax example	Result	Instructions
+	{{ 1 + 2 }}	3	Addition, only applicable to numbers, cannot be used to concatenate strings
-	{{ 5 - 3 }}	2	Subtraction
*	{{ 4 * 2 }}	8	Multiplication
/	{{ 5 / 2 }}	2.5	Division
//	{{ 7 // 2 }}	3	Integer division (quotient)
%	{{ 11 % 7 }}	4	Modulus (remainder)

Comparison operators

Can be used directly with == ,!=, <, >, >= and <=, and will return a boolean value based on the comparison result.

• ==: equal to.

• -!: not equal to.

• <: less than.

• >: greater than.

• >=: greater than or equal to.

• <=: less than or equal to.

For more complex comparisons, you can use matchesThe matches operator compares using regular expressions.

{% if phone_number matches '/^[\\d\\.]+$/' %}
{% endif %}

Ternary (conditional) operator

This operator accepts two operands as values and one operand as the condition. The syntax is:condition ? value1 : value2 , below are some simple examples.

{{ name ? 'yes' : 'no' }}

{{ age >= 18 ? 'adult' : 'child' }}

Logical operators

You can use ?? to evaluate OR logic; if expression1 is present/true, it returns expression1; otherwise it returns expression2.

{# If age is not null, display the value of name; otherwise display unknown #}
{{ name ?? 'unknown' }}

Flow control

Flow control refers to conditional statements that control the flow, such asif,elseif,else,foretc. Control syntax should be placed within {% ... %} delimiter content.

if...else

When the condition is met, the statements inside the if block will be executed; when it is not met, another statement will be executed.

{% if age >= 18 %}
    Adult
{% else %}
    Minor
{% endif %}

{# Check whether a value exists #}
{% if users is defined %}
  {{ user.username }}
{% endif %}

for

Repeatedly executes until a specified condition evaluates to false; it stops executing when the condition no longer holds. Within the for block, you can use built-in special variables. The special variables are as follows:

Variable name	Description
loop.index	Displays the current index, starting from 1
loop.index0	Displays the current index, starting from 0
loop.length	Length of the array
loop.first	Returns true if it is the first item of the array
loop.last	Returns true if it is the last item of the array

{% for user in users %}
    {{ user.name }}
{% endfor %}

{# You can also use else to handle the case when the array is empty, for example #}
{% for user in users %}
    {{ loop.index }} - {{ user.name }}
{% else %}
    No users have been found.
{% endfor %}

Below is a description written for the usage of split based on the tone and format you provided; it can be directly appended to the original tutorial content:

---

Text filters

Operator

Operator / method	Syntax example	Result / function	Instructions
~	{{ 'Hello, ' ~ name }}	Hello, Eason	String concatenation operator, will automatically convert variables to strings, even if they are null

String split

When you need to split a piece of text into multiple parts based on a delimiter, you can use the split feature. For example, to split a name into a list of characters so you can access each character individually:

{{ name|split('') }}

{# If name is “王小明”, executing this will produce: #}
['王', '小', '明']

You can also specify a particular delimiter to split by, for example a comma-separated list of color tags:

{{ 'red,blue,green'|split(',') }}

{# The result is: #}
[['red', 'blue', 'green']

The split data can be processed one by one using the for syntax, commonly used for displaying tags, decomposing text content, and other needs.

Date filters

The date syntax can accept strings or DateTime objects. For example, to display the current date, pass the word “now” as the parameter to the syntax.

Display current time

// Output is 2022-05-12 22:21:10
{{ 'now' | date('Y-m-d H:i:s') }

Specify timezone

By default, dates will use the FIRST LINE server’s timezone for display, but you can override it by explicitly specifying a timezone:

// Specify a special timezone conversion
{{ 'now' | date('Y-m-d H:i:s', 'Asia/Tokyo') }}

If the date is already a DateTime object and you want to keep its current timezone, pass the timezone value as false.

{{ product.created_at | date('Y-m-d H:i:s', false) }}