change Block

The change block is used to set, change, delete or move properties of a message, flow context or global context. The node can specify multiple rules that will be applied in the order they are defined.

Overview

The change block provides four main operations:

• Set: Set a property. The value can be a variety of different types, or can be taken from an existing message or context property.
• Change: Search & replace parts of the property. If regular expressions are enabled, the "replace with" property can include capture groups, for example $1. Replace will only change the type if there is a complete match.
• Delete: Delete a property.
• Move: Move or rename a property.

The "expression" type uses the JSONata query and expression language.

Configuration Options

Operations

The block supports multiple operations that can be configured:

Set Operations

• Set msg.property: Set a property in the message object
• Set flow.property: Set a property in the flow context
• Set global.property: Set a property in the global context

Change Operations

• Change msg.property: Modify an existing message property
• Change flow.property: Modify an existing flow context property
• Change global.property: Modify an existing global context property

Move Operations

• Move msg.property: Move a property from one location to another
• Move flow.property: Move a flow context property
• Move global.property: Move a global context property

Delete Operations

• Delete msg.property: Remove a property from the message
• Delete flow.property: Remove a property from flow context
• Delete global.property: Remove a property from global context

Value Types

For each operation, you can specify the value type:

• String: Plain text value
• Number: Numeric value
• Boolean: True/false value
• JSON: JSON object or array
• Date: Date/time value
• JSONata Expression: Dynamic expression evaluation
• Environment Variable: System environment variable
• Flow/Global Context: Reference to context values

Common Use Cases

Data Transformation

Transform incoming data to match expected format:

{
  "operations": [
    {
      "action": "set",
      "target": "msg.payload.processedAt",
      "value": "{{$now()}}",
      "valueType": "jsonata"
    },
    {
      "action": "set",
      "target": "msg.payload.status",
      "value": "processed",
      "valueType": "str"
    }
  ]
}

Property Mapping

Map properties from one structure to another:

{
  "operations": [
    {
      "action": "move",
      "target": "msg.payload.userId",
      "source": "msg.payload.id"
    },
    {
      "action": "move",
      "target": "msg.payload.userName",
      "source": "msg.payload.name"
    }
  ]
}

Context Management

Store and retrieve values from context:

{
  "operations": [
    {
      "action": "set",
      "target": "flow.processedCount",
      "value": "{{flow.processedCount + 1}}",
      "valueType": "jsonata"
    },
    {
      "action": "set",
      "target": "global.lastProcessed",
      "value": "{{$now()}}",
      "valueType": "jsonata"
    }
  ]
}

Data Cleaning

Remove unnecessary properties:

{
  "operations": [
    {
      "action": "delete",
      "target": "msg.payload.tempData"
    },
    {
      "action": "delete",
      "target": "msg.payload.debugInfo"
    }
  ]
}

Advanced Features

JSONata Expressions

Use JSONata expressions for dynamic value calculation:

{
  "operations": [
    {
      "action": "set",
      "target": "msg.payload.fullName",
      "value": "{{payload.firstName & ' ' & payload.lastName}}",
      "valueType": "jsonata"
    }
  ]
}

Conditional Operations

Apply operations based on conditions:

{
  "operations": [
    {
      "action": "set",
      "target": "msg.payload.priority",
      "value": "{{payload.amount > 1000 ? 'high' : 'normal'}}",
      "valueType": "jsonata"
    }
  ]
}

Tips

• Use the change block early in your flow to standardize data formats
• Combine multiple operations in a single change block for efficiency
• Use JSONata expressions for complex data transformations
• Store frequently used values in flow or global context
• Use meaningful property names to improve flow readability
• Test your JSONata expressions using the expression editor

Notes

• The change block processes operations in the order they are configured
• Context values persist across message flows within the same flow or globally
• JSONata expressions have access to the current message and context
• The block can handle multiple operations in a single execution
• Property paths use dot notation (e.g., msg.payload.user.name)

Related Blocks

• function - For complex custom logic
• template - For text formatting
• switch - For conditional routing