Set Variable

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

The Set Variable node stores computed or static values in the workflow execution context. Variables persist for the entire duration of the execution and are accessible by any downstream node.

Handles

Handle	Direction	Description
input	Input	Receives data from the preceding node
output	Output	Passes input data unchanged

Configuration

Field	Type	Default	Description
variables	array	[]	Array of variable definition objects

Variable Definition Object

{
    "name": "order_total",
    "value": "{{quantity}} * {{unit_price}}",
    "scope": "local",
    "mode": "overwrite"
}

Property	Type	Options	Description
name	string	—	Variable name
value	mixed	—	Value to assign; supports {{tags}} and expressions
scope	enum	local, global	Variable persistence scope
mode	enum	overwrite, merge	How to handle existing variables

Available Tags

When the Set Variable node is connected to an upstream node, it automatically discovers and displays all available fields as clickable tags. Click any tag to copy it to your clipboard in {{tag}} format, ready to paste into any Value field.

Tags are resolved at execution time by the Expression Engine, which flattens all upstream input fields to the root level. This means you can reference any upstream field directly without prefixes:

Upstream field	Tag syntax
product	{{product}}
quantity	{{quantity}}
unit_price	{{unit_price}}

Expression Engine

The Value field is evaluated by the Symfony ExpressionLanguage engine, which supports:

• Arithmetic: {{quantity}} * {{unit_price}}
• String concatenation (operator ~): "Order: " ~ {{product}} ~ " x" ~ {{quantity}}
• Helper functions: $upper({{name}}), $round({{total}}, 2), $dateFormat($now(), "d/m/Y")
• Static values: 42, "hello", true

For a full list of available functions, see the Expression node documentation.

Scopes

local

The variable is scoped to the current execution. It is stored in the execution's context.vars object and is accessible to all downstream nodes in the same run.

global

The variable is persisted to the voodflow_global_variables table and is shared across all future executions of all workflows. Use with caution — global variables are mutable application state.

Modes

overwrite

Replaces the existing value entirely:

Before: counter = 5
After:  counter = 10

merge

If the existing value and the new value are both objects/arrays, performs a deep merge. Otherwise falls back to overwrite:

Before: user_data = { "name": "Alice" }
New:    { "city": "Roma" }
After:  user_data = { "name": "Alice", "city": "Roma" }

Accessing Variables Downstream

Variables set by this node are available downstream in two ways:

In template fields (TagReplacer)

Variables are flattened to the root context, so use them directly:

Title:   New Order: ${{order_total}}
Body:    {{order_summary}}
URL:     https://api.example.com/{{region}}/data

In PHP Code node

$apiKey = $context->getVar('api_key');
$counter = $context->getVar('counter', 0);

Preset Example

💾 Try this example

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

This example demonstrates:

1. Manual Trigger → Dummy Data (order JSON with product, quantity, unit_price, customer)
2. Set Variable computes order_total ({{quantity}} * {{unit_price}}) and order_summary (string concatenation with ~)
3. System Notification displays the computed variables using {{order_total}} and {{order_summary}}

Set Variable inside If/Merge workflow

💾 Try this example

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

Examples

Compute an Order Total

Variables:
    - name: order_total
      value: "{{quantity}} * {{unit_price}}"
      scope: local
      mode: overwrite

Build a Summary String

Variables:
    - name: order_summary
      value: '"Order for " ~ {{customer}} ~ ": " ~ {{quantity}} ~ "x " ~ {{product}}'
      scope: local
      mode: overwrite

Store an API Base URL

Variables:
    - name: api_base_url
      value: https://api.example.com/v2
      scope: local
      mode: overwrite

Then in HTTP Request: URL: {{api_base_url}}/users

Increment a Counter (Global)

Variables:
    - name: daily_email_count
      value: "{{daily_email_count}} + 1"
      scope: global
      mode: overwrite

Store a Period Description

Variables:
    - name: period_label
      value: '"Week of " ~ $dateFormat($now(), "d/m/Y")'
      scope: local
      mode: overwrite

Merge Enrichment Data

Variables:
    - name: order_context
      value: '{ "currency": "EUR", "tax_rate": 0.22 }'
      scope: local
      mode: merge

Notes

• The Set Variable node does not modify $context->input — input passes through unchanged
• Variable names should be lowercase with underscores (snake_case) for consistency
• Global variables are visible to all workflows — use meaningful, namespaced names to avoid collisions
• Variable values are resolved at execution time; {{tags}} in value are expanded before storing
• The Available Tags section shows fields from all connected upstream nodes
• Tags use simple {{field}} syntax — the Expression Engine flattens input fields to the root level automatically