Soracom Flux

Use Expressions in Actions

In this document, we explain the syntax of the expressions you can use in Action Condition and some Action Config fields. These expressions are used to access and evaluate the Message and Context of event messages received from the channel. In action condition fields, you can use these expressions to conditionally execute actions based on data in event message. In some action config fields, you can also use these expressions to dynamically customize the input data for the action.

Action Condition Expressions

In action conditions, expressions evaluate to a boolean value (true or false).

The condition is evaluated each time the channel receives a new event. If the result of the evaluation is true, the action is executed.

For example, this expression is evaluated as true when the Message of an event sent to the channel is {"temperature": 42} and the current day of the week in UTC is Monday.

(payload.temperature - 2.12) >= 32.8 && getUTCDayOfWeek(now()) == 1

Similarly, the following expression is evaluated as true when the Message sent from the event source is {"clicktype": "SINGLE"} or when the Context sent to the channel contains {"protocol": "http"}.

startsWith(toUpperCase(event.payload.clicktype), "SINGLE") || context.protocol == "http"

Action Config Expressions

In supported action config input fields, expressions evaluate to strings.

The action config expression is evaluated when the action is executed. The evaluated result is used as the action's input.

For example, if the event is {"presignedUrls": {"get": "https://example.com"}}, the output of the following expression will be <https://example.com|Image>.

<${event.payload.presignedUrls.get}|Image>

For another example, if the event is {"output": {"people": 3, "people_with_blue_shirts": 0}}, the output of the following expression will be There are 3 people. Among them, 0 are wearing blue shirts!.

There are ${payload.output.people} people. Among them, ${payload.output.people_with_blue_shirts} are wearing blue shirts!

Likewise, to get the number of elements in the weather array from {"weather": ["sunny", "cloudy", "rain"]} in the MESSAGE (the output data of the previous channel), use the following expression:

${len(payload.weather)}

Expression Syntax Reference

Expressions in Action Condition and Action Config fields can include variables, operators, and functions. The following is a reference of the syntax you can use in these expressions.

Variables

Variable	Description
payload	The Message sent to the channel. If it's a JSON object, you can access JSON object values using syntax such as payload.temperature or payload.values[1].foo["click type"]. If it's not a JSON object, payload is treated as a string.
context	A JSON object corresponding to the Context sent to the channel. The schema of the object varies by event type. Refer to each Event Source reference for more details. For example: IoT Device Event Source
event.payload	The original Message sent from the event source to the channel.
event.context	A JSON object corresponding to the Context sent from the event source to the channel.

Operators

Operator	Description
||	Logical OR: Returns true if either condition is true.
&&	Logical AND: Returns true if both conditions are true.
? :	Ternary operator: Used as a ? b : c, it returns b if the condition a is evaluated as true, and c if evaluated as false. For example: event.payload.click_type == 1 ? "Single click" : "Double click"
==	Equal to: Returns true if the values are equal.
!=	Not equal to: Returns true if the values are not equal.
>=	Greater than or equal to: Returns true if the left value is greater than or equal to the right value.
>	Greater than: Returns true if the left value is greater than the right value.
<=	Less than or equal to: Returns true if the left value is less than or equal to the right value.
<	Less than: Returns true if the left value is less than the right value.
+	Addition: Returns the sum of two values.
-	Subtraction: Returns the difference of two values.
*	Multiplication: Returns the product of two values.
/	Division: Returns the quotient of two values.
%	Modulus: Returns the remainder when the left value is divided by the right value.
**	Exponentiation: Returns the result of raising the left value to the power of the right value.

Functions

Evaluating Values

Function	Description
includes(string, value)	Checks if string contains value, returning true or false.
startsWith(string, prefix)	Checks if string begins with prefix, returning true or false.
endsWith(string, suffix)	Checks if string ends with suffix, returning true or false.

Data Conversion

Function	Description
toLowerCase(string)	Converts string to lowercase.
toUpperCase(string)	Converts string to uppercase.
int(value)	Converts a string or number to an integer. Decimal values are truncated.
toNumber(string)	Converts a string to a number.
toString(number)	Converts a number to a string.
abs(number)	Returns the absolute value of number.
ceil(number)	Rounds number up to the nearest integer.
floor(number)	Rounds number down to the nearest integer.
round(number)	Rounds number to the nearest integer.
max(number1, number2)	Returns the larger of the two specified numbers. number1 and number2 must be integers.
min(number1, number2)	Returns the smaller of the two specified numbers. number1 and number2 must be integers.
len(value)	Returns the length of a string or array. The length of a string is determined by counting the number of Unicode code points. For an array, use a variable that contains an array (e.g. len(payload))

Time processing

Function	Description
now()	Returns current Unix time (milliseconds).
datetime(iso_string)	Converts a date string to Unix time (milliseconds).*2
datetimeFromISOString(iso_string)	Converts a date string to Unix time (milliseconds).*2
getUTCYear(value)	Returns the UTC year, where value can be a Unix time (milliseconds) or a date string.*2
getUTCMonth(value)	Returns the UTC month, where value can be a Unix time (milliseconds) or a date string.*2
getUTCDate(value)	Returns the UTC day, where value can be a Unix time (milliseconds) or a date string.*2
getUTCHours(value)	Returns the UTC hour, where value can be a Unix time (milliseconds) or a date string.*2
getUTCMinutes(value)	Returns the UTC minute, where value can be a Unix time (milliseconds) or a date string.*2
getUTCSeconds(value)	Returns the UTC second, where value can be a Unix time (milliseconds) or a date string.*2
getUTCMilliseconds(value)	Returns the UTC milliseconds, where value can be a Unix time (milliseconds) or a date string.*2
getUTCDayOfWeek(value)	Returns the UTC day of the week as a number (0 = Sunday), where value can be a Unix time (milliseconds) or a date string.*2
addSeconds(value, number)	Adds the specified number of seconds, where value can be a Unix time (milliseconds) or a date string.*1,*2
addMinutes(value, number)	Adds the specified number of minutes, where value can be a Unix time (milliseconds) or a date string.*1,*2
addHours(value, number)	Adds the specified number of hours, where value can be a Unix time (milliseconds) or a date string.*1,*2
addDays(value, number)	Adds the specified number of days, where value can be a Unix time (milliseconds) or a date string.*1,*2
addMonths(value, number)	Adds the specified number of months, where value can be a Unix time (milliseconds) or a date string.*1,*2
addYears(value, number)	Adds the specified number of years, where value can be a Unix time (milliseconds) or a date string.*1,*2

*1 - The function rounds down if number is a decimal.
*2 - Required date string format: YYYY-MM-DDThh:mm:ssTZD (e.g., 2025-01-23T04:56:30+01:00) or YYYY-MM-DDThh:mm:ss.sssTZD (e.g., 2025-01-23T04:56:30.456+01:00)