set

Overview

The set node modifies message properties through a list of configurable rules. Each rule can set a property to a new value, delete an existing property, or move a property from one location to another. Multiple rules execute in order, making it easy to reshape messages for downstream nodes without writing any code.

Properties

Rule Types

// Set msg.payload.status to "ok"
// Set msg.headers.auth to env var
// Set msg.timestamp to Date.now()

// Delete msg.payload.password
// Delete msg._internal
// Delete msg.debug

// Move msg.data to msg.payload
// Move msg.temp to msg.sensors.temp
// Move msg.raw to msg._backup

Example: Rename Payload Fields for API Compatibility

Transform sensor data field names to match a third-party API schema.

// Set node configuration
{
  "rules": [
    // Rename "temp" to "temperature"
    { "type": "move", "property": "payload.temp", "to": "payload.temperature" },

    // Rename "hum" to "humidity"
    { "type": "move", "property": "payload.hum", "to": "payload.humidity" },

    // Rename "loc" to "location"
    { "type": "move", "property": "payload.loc", "to": "payload.location" },

    // Remove internal debug field
    { "type": "delete", "property": "payload._debug" },

    // Set API version header
    { "type": "set", "property": "headers.X-API-Version", "value": "2.1" }
  ]
}

// Input:  { temp: 22.5, hum: 65, loc: "Room A", _debug: true }
// Output: { temperature: 22.5, humidity: 65, location: "Room A" }

Example: Add Timestamp and Metadata to Messages

Enrich incoming messages with processing metadata before storing in a database.

// Set node configuration
{
  "rules": [
    // Add processing timestamp
    { "type": "set", "property": "payload.processedAt", "value": "$now()" },

    // Add device identifier from flow context
    { "type": "set", "property": "payload.deviceId", "value": "flow.deviceId" },

    // Add environment tag
    { "type": "set", "property": "payload.env", "value": "production" },

    // Add message version
    { "type": "set", "property": "payload.schemaVersion", "value": 3 },

    // Move raw data into nested object
    { "type": "move", "property": "payload.value", "to": "payload.data.reading" },

    // Delete sensitive source info
    { "type": "delete", "property": "payload.sourceIP" }
  ]
}

// Input:  { value: 42, sourceIP: "192.168.1.10" }
// Output: { data: { reading: 42 }, processedAt: "2025-...",
//          deviceId: "sensor-01", env: "production", schemaVersion: 3 }

Common Use Cases