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Build Payload node

Build Payload Node

Overview

The Build Payload Node assembles a structured, schema-aligned object from upstream data by evaluating direct JavaScript expressions for each field.
It is ideal when you want a strongly-typed, well-documented payload (often aligned with a UNS schema) but you still need full flexibility to compute each field from raw inputs, combined sources, or other computed fields.

Unlike template-style nodes that use {{ }} expressions, Build Payload works with plain JavaScript code and an execution engine that:

• Resolves field dependencies (via $fields) automatically.
• Reads the previous node's output as $input, and any upstream node by name with $node["Name"].
• Performs type conversion into the field's type (string, bool, integers, floats, datetime and more).
• Always produces one object, with one key per field.

Configuration Reference

Parameters

Parameter	Type	Default	Required	Description
Field source	select	Custom	No	UNS Schema fills the fields from a UNS data schema (needs the UNS licence); Custom lets you define the fields by hand.
Schema (Optional)	select	—	No	Shown when Field source is UNS Schema. Picking a schema fills the field list from its attributes.
Field Definitions	array	[]	No	Field definitions for the payload, evaluated top to bottom. With no fields, the input passes through unchanged.

Field Definition (fields[])

Property	Type	Description
Field Name	string	Output key of the field (e.g., firstName). Names must be unique.
Field Type	select	Type the value is converted to: string, bool, datetime, float32, float64, int8, int16, int32, int64, uint8, uint16, uint32, uint64, bytes, decimal, duration, uuid, timeseries_ref.
Expression	string (JS)	JavaScript code that returns the field value. Has access to $input, $node, $trigger, and $fields.
Required	boolean	On: the node fails when the field has no expression, the expression throws, returns nothing, or its value can't be converted. Off: the field is set to null, the problem is listed in _metadata.errors, and the node finishes as completed with errors.

Settings

Setting	Options	Default	Description
Timeout (seconds)	number	Pipeline default	Maximum execution time for this node (1--600).
Retry on Timeout	Pipeline Default / Enabled / Disabled	Pipeline Default	Whether to retry on timeout.
Retry on Fail	Pipeline Default / Enabled / Disabled	Pipeline Default	Whether to retry on failure. When Enabled, shows Advanced Retry Configuration.
On Error	Pipeline Default / Stop Pipeline / Continue Execution	Pipeline Default	Behavior when node fails after all retries.

Advanced Retry Configuration

Only visible when Retry on Fail is set to Enabled.

Field	Type	Default	Range	Description
Max Attempts	number	3	1--10	Maximum retry attempts.
Initial Delay (ms)	number	1000	100--30,000	Wait before first retry.
Max Delay (ms)	number	120000	1,000--300,000	Upper bound for backoff delay.
Multiplier	number	2.0	1.0--5.0	Exponential backoff multiplier.
Jitter Factor	number	0.1	0--0.5	Random jitter.

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Expression Examples

Simple Field Calculations

// Capitalize a name
$input[0].result.firstName.toUpperCase()

// Calculate year
new Date().getFullYear() 

// Mark adults vs minors
$input[0].result.age >= 18

Using $node for Cross-Node Data

// Read a field from a named upstream node
$node['Read Sensor'].result.temperature

// Combine data from multiple upstream nodes
$node['Fetch User'].result.name + ' (' + $node['Fetch Roles'].result.role + ')'

// Access nested data from a connector node
$node['REST Request'].result.body.items[0].id

Using $fields for Dependencies

// fullName field
$input[0].result.firstName + ' ' + $input[0].result.lastName

// greeting field that reuses fullName
'Hello, ' + $fields.fullName

// totalPrice based on other calculated fields
$fields.unitPrice * $fields.quantity

Usage Examples

Example 1: Normalize User Profile Payload

Field	Value
Field source	Custom (define fields manually)

Fields:

Name	Type	Expression
firstName	string	$input[0].result.first_name
lastName	string	$input[0].result.last_name
age	int32	$input[0].result.age
fullName	string	$fields.firstName + ' ' + $fields.lastName

The node converts an arbitrary incoming object into a clean, typed user profile. None of the fields is Required, so a missing value becomes null and is listed in _metadata.errors instead of failing the node.

Example 2: Summarize a List of Orders

The previous node returns a list of orders as its result:

[
  { id: 'ORD-1', amount: 42.5, currency: 'USD' },
  { id: 'ORD-2', amount: 103.0, currency: 'USD' }
]

Fields:

Name	Type	Expression
orderCount	int32	$input[0].result.length
totalAmount	float64	$input[0].result.reduce((sum, o) => sum + o.amount, 0)
firstOrderId	string	$input[0].result[0].id

The output is one object, { orderCount: 2, totalAmount: 145.5, firstOrderId: 'ORD-1' }. Build Payload doesn't run once per list item; to build one payload per order, place it inside a For-Each Loop and read the order with $item.

Example 3: Merge Data from Multiple Upstream Nodes

Field	Value
Field source	Custom (define fields manually)

Fields (all marked Required):

Name	Type	Expression
sensorId	string	$node['Read Sensor'].result.id
temperature	float64	$node['Read Sensor'].result.temperature
operatorName	string	$node['Fetch Operator'].result.name
lineName	string	$node['Fetch Operator'].result.assignedLine
label	string	$fields.operatorName + ' — ' + $fields.lineName

The node pulls data from two upstream nodes and combines them into a single, flat object. The label field uses $fields to reference previously computed fields. Because every field is Required, the node fails if either upstream value is missing.

When to Use Build Payload

Use the Build Payload node when you need:

• A strongly-typed, schema-aligned payload in the middle of a pipeline.
• Complex field calculations using full JavaScript rather than inline {{ }} expressions.
• To merge data from multiple upstream nodes into a single, well-structured object.

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Configuration reference

The fields below are generated from the node's config contract, so they match what the pipeline validator enforces and what the designer's form offers.

functions.instance.data

Field	Type	Required	Default	Values	Description
fields	object[]	no	—	—	Fields of the payload, evaluated top to bottom; a later field may read an earlier one as $fields.<name>. Names must be unique — the output has one slot per name. With no entries the input passes through unchanged