jsTransform component: script transformer. You can use JavaScript script to transform or enhance msg, metadata, msgType. Then pass the transformed message to the next node.

JavaScript script supports ECMAScript 5.1(+) syntax specification and some ES6 specifications, such as: async/await/Promise/let. It allows calling Go custom functions in the script, please refer to udf .

Configuration

Field	Type	Description	Default value
jsScript	string	js script	None

• jsScript: You can transform or enhance msg, metadata, msgType. This field is the following function body content

      function Transform(msg, metadata, msgType) { 
          ${jsScript} 
       }
  

  • msg: Message content, if dataType=JSON, type is: jsonObject, you can use msg.temperature to operate. If dataType is other types, the field type is:string
  • metadata: Message metadata, type: jsonObject
  • msgType: Message type
  • Function return value type: {'msg':msg,'metadata':metadata,'msgType':msgType};

Note

Script execution timeout configuration reference: config.ScriptMaxExecutionTime

Relation Type

• Success: Execution successful, send the message to the Success chain
• Failure: Execution failed, send the message to the Failure chain

Execution result

Change the content of msg, metadata and msgType through the script.

Configuration example

  {
    "id": "s1",
    "type": "jsTransform",
    "name": "Transform",
    "configuration": {
      "jsScript": "metadata['name']='test01';\n metadata['index']=11;\n msg['addField']='addValue1'; return {'msg':msg,'metadata':metadata,'msgType':msgType};"
    }
  }

Application example

Transform the message and then execute the subsequent logic.

{
  "ruleChain": {
    "id":"rule01",
    "name": "Test rule chain",
    "root": true
  },
  "metadata": {
    "nodes": [
       {
        "id": "s1",
        "type": "jsTransform",
        "name": "Transform",
        "configuration": {
          "jsScript": "metadata['name']='test02';\n metadata['index']=22;\n msg['addField']='addValue2'; return {'msg':msg,'metadata':metadata,'msgType':msgType};"
        }
      },
      {
        "id": "s2",
        "type": "restApiCall",
        "name": "Push data",
        "configuration": {
          "restEndpointUrlPattern": "http://192.168.136.26:9099/api/msg",
          "requestMethod": "POST",
          "maxParallelRequestsCount": 200
        }
      }
    ],
    "connections": [
      {
        "fromId": "s1",
        "toId": "s2",
        "type": "Success"
      }
    ]
  }
}