Expression

Type key: expression_node
Group: Data
Category: data
Tier: CORE

The Expression node evaluates dynamic expressions to compute new fields, perform calculations, transform strings, and apply conditional logic. It is more powerful than simple {{tag}} replacement and is the go-to tool for computed fields without writing PHP.

Handles

Handle	Direction	Description
input	Input	Receives data from the preceding node
output	Output	Emits input data with computed fields added/replaced

Configuration

Field	Type	Default	Description
expressions	array	[]	Array of expression definitions
pass_through_input	boolean	true	Include all original input fields in the output
evaluation_mode	enum	per_record	per_record or dataset

Expression Object

{
    "field": "price_with_tax",
    "expression": "{{input.price}} * 1.22"
}

Property	Description
field	Output field name where the result is stored
expression	The expression to evaluate

Expression Syntax

Arithmetic

{{input.subtotal}} + {{input.shipping}}
{{input.quantity}} * {{input.unit_price}}
{{input.total}} / {{input.count}}
{{input.value}} % 100

Comparison (returns boolean)

{{input.score}} > 80
{{input.age}} >= 18
{{input.status}} == "active"

Ternary Operator

{{input.quantity}} >= 10 ? 0.15 : 0.05
{{input.vip}} == true ? "VIP" : "Standard"

String Concatenation

{{input.first_name}} + " " + {{input.last_name}}

Built-in Functions

String Functions

Function	Description	Example
$upper(str)	Convert to uppercase	$upper({{input.name}})
$lower(str)	Convert to lowercase	$lower({{input.email}})
$trim(str)	Remove whitespace	$trim({{input.code}})
$length(str)	String length	$length({{input.description}})
$replace(str, search, replace)	Replace substring	$replace({{input.text}}, "foo", "bar")
$contains(str, needle)	Check substring	$contains({{input.tags}}, "urgent")
$substr(str, start, length)	Extract substring	$substr({{input.code}}, 0, 3)

Math Functions

Function	Description	Example
$round(num, decimals)	Round to N decimal places	$round({{input.price}}, 2)
$floor(num)	Round down	$floor({{input.score}})
$ceil(num)	Round up	$ceil({{input.average}})
$abs(num)	Absolute value	$abs({{input.delta}})
$min(a, b)	Minimum	$min({{input.a}}, {{input.b}})
$max(a, b)	Maximum	$max({{input.a}}, {{input.b}})

Date Functions

Function	Description	Example
$dateFormat(date, format)	Format a date	$dateFormat({{input.created_at}}, "d/m/Y")
$dateDiff(date1, date2, unit)	Difference between dates	$dateDiff({{input.start}}, {{now}}, "days")
$dateAdd(date, amount, unit)	Add time to a date	$dateAdd({{input.date}}, 7, "days")
$now()	Current datetime string	$now()

Currency Functions

Function	Description	Example
$currency(value, code, locale, decimals)	Format a number as currency string	$currency({{input.total}}, "EUR", "it_IT", 2)
$currency_it(value, decimals)	Shortcut for EUR + italian locale	$currency_it({{input.total}}, 2)

Function signature:

$currency(value, currencyCode = 'EUR', locale = 'it_IT', decimals = 2)

• value: numeric value to format
• currencyCode: ISO-like code (e.g. EUR, USD, GBP, CHF, JPY)
• locale: formatting style hint (e.g. it_IT, en_US, de_DE)
• decimals: number of decimal digits

Important: locale must be a quoted string literal:

$currency({{input.total}}, "USD", "en_US", 2)   // ✅
$currency({{input.total}}, "USD", en_US, 2)     // ❌

Examples by locale:

$currency({{input.total}}, "EUR", "it_IT", 2)   // 4.048,00 €
$currency({{input.total}}, "USD", "en_US", 2)   // $ 4,048.00

Important: currency helpers do not divide by 100 automatically. If your values are in cents, divide explicitly:

$currency({{input.total}} / 100, "EUR", "it_IT", 2)

Evaluation Modes

per_record

Expressions are evaluated once per item in the dataset. Use this when the input is a single record or when processing inside a For Each loop.

dataset

Expressions are evaluated once against the entire dataset object. Use this for meta-level computations that operate on the whole context (e.g. counting records, computing totals across the dataset).

Examples

Calculate Total with VAT

{
    "field": "total_with_vat",
    "expression": "{{input.subtotal}} * 1.22"
}

💾 Try this example

Download the workflow JSON — open an empty workflow and import the file.

Expression inside For Each (greeting per user)

With For Each, each iteration exposes the current item as input. An Expression node in per_record mode can build fields such as a personalized greeting from {{input.name}}.

💾 Try this example

Download the workflow JSON — open an empty workflow and import the file.

Conditional Discount

{
    "field": "discount_rate",
    "expression": "{{input.quantity}} >= 10 ? 0.15 : 0.05"
}

Clean and Normalize Name

{
    "field": "clean_name",
    "expression": "$upper($trim({{input.name}}))"
}

Days Since Created

{
    "field": "days_since_registration",
    "expression": "$dateDiff({{input.created_at}}, $now(), \"days\")"
}

Notes

• When pass_through_input: true, all original fields are preserved and new computed fields are added alongside them
• When pass_through_input: false, only the fields listed in expressions appear in the output
• Expression evaluation errors (division by zero, invalid types) result in null for that field, not a node failure
• For complex logic that outgrows the expression engine, use the PHP Code node