JavaScript transform tutorials

Tutorials for the JavaScript transform method

This document provides tutorials for using the JavaScript transform method, specifically for recalculating Celsius temperatures as Fahrenheit. It details creating a JavaScript code package to convert the temperature, setting up an integration table transform that utilizes this package, creating an integration table, inserting a record with a Celsius temperature, and querying the results to see the calculated Fahrenheit temperature. The tutorial outlines the JSON payloads for each step, showing how the data flows and is transformed.

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Recalculate a Celsius temperature a Fahrenheit

This tutorial creates a JavaScript code package to read a "temperatureCelsius" property out of a JSON document in the source_payload field. It assumes the temperature value is Celsius, converts it to Fahrenheit, and writes the result to the temperature_fahrenheit field.

Create a JavaScript code package

// integrationTableTransform returns a modified record
// Server sets the record variable before running the code package
try {
  
  let temperatureCelsius = record.source_payload.temperatureCelsius;
  let temperatureFahrenheit = (temperatureCelsius * 1.8) + 32;
  
  record.temperature_fahrenheit = temperatureFahrenheit;
  
} catch (err) {
  record.transformError = err.message;
}

The code package uses JavaScript to read a "temperatureCelsius" property out of the JSON document in the source_payload field. It assumes the temperature value is Celsius, converts it to Fahrenheit, and writes the result to the temperature_fahrenheit field. When you assign this transform to an integration table, the server automatically creates the temperature_fahrenheit field if it does not already exist.

{
  "api": "admin",
  "apiVersion": "1.0",
  "action": "createCodePackage",
  "params": {
    "databaseName": "faircom",
    "ownerName": "admin",
    "codeName": "convertCelsiusToFahrenheit",
    "newCodeName": "convertCelsiusToFahrenheit",
    "codeLanguage": "javascript",
    "codeFormat": "utf8",
    "codeType": "integrationTableTransform",
    "codeStatus": "testing",
    "description": "Converts the value of the \"temperature_celsius\" field to Fahrenheit and stores the result in the temperature_fahrenheit field.",
    "metadata": {
      "defaultIntegrationTableName": "mod1",
      "inputFields": [
        "source_payload"
      ],
      "outputFields": [
        "temperature_fahrenheit"
      ],
      "outputFieldDefinitions": [
        {
          "name": "temperature_fahrenheit",
          "type": "integer"
        }
      ]
    },
    "comment": "",

    "code": "// integrationTableTransform returns a modified record\n// Server sets the record variable before running the code package \ntry {\n\n    let temperatureCelsius = record.source_payload.temperatureCelsius;\n    let temperatureFahrenheit = (temperatureCelsius * 1.8) + 32;\n\n    record.temperature_fahrenheit = temperatureFahrenheit;\n\n} catch (err) {\n    record.transformError = err.message;\n}"

  },
  "authToken": "replaceWithAuthTokenFromCreateSession"
}

Create an integration table transform

This transform contains one step, which runs the previously created JavaScript code package.

It specifies that the transform requires the temperature_fahrenheit field to store its results. When you assign this transform to an integration table, the server automatically creates the temperature_fahrenheit field if it does not already exist.

{
  "api": "transform",
  "apiVersion": "1.0",
  "action": "createTransform",
  "params": {
    "transformName": "Tutorial: Convert Celsius to Fahrenheit",
    "transformActions": [
      {
        "transformStepName": "JavaScript Transform: Convert Celsius to Fahrenheit ",
        "transformStepMethod": "javascript",
        "transformService": "v8TransformService",

        "inputFields": [
          "source_payload"
        ],
        "outputFields": [
          "temperature_fahrenheit"
        ],

        "transformParams": {
          "codeName": "convertCelsiusToFahrenheit",
          "databaseName": "faircom",
          "ownerName": "admin",
          "outputFieldDefinitions": [
            {
              "name": "temperature_fahrenheit",
              "type": "integer"
            }
          ]
        }
      }
    ]
  },
  "authToken": "replaceWithAuthTokenFromCreateSession"
}

Create an integration table

Create an integration table and connect it to a JavaScript transform that runs each time you insert a record.

{
  "api": "hub",
  "apiVersion": "1.0",
  "action": "createIntegrationTable",
  "params": {
    "tableName": "test1",
    "ownerName": "admin",
    "databaseName": "faircom",

    "transformName": "Tutorial: Convert Celsius to Fahrenheit"
  },
  "authToken": "replaceWithAuthTokenFromCreateSession"
}

Insert a record

Insert a record into the table to run the transform on that record and populate the temperature_fahrenheit field.

Notice that we are only inserting a value into the source_payload field.

{
  "api": "db",
  "apiVersion": "1.0",
  "action": "insertRecords",
  "params": {
    "tableName": "test1",
    "dataFormat": "objects",
    "sourceData": [
      {
        "source_payload": { "temperatureCelsius": 20 }
      }
    ]
  },
  "authToken": "replaceWithAuthTokenFromCreateSession"
}

Query the results

{
  "api": "db",
  "apiVersion": "1.0",
  "action": "getRecordsByTable",
  "params": {
    "tableName": "test1"
  },
  "authToken": "replaceWithAuthTokenFromCreateSession"
}

Results

The temperature_fahrenheit field contains 68. When you inserted the record, the server automatically ran the JavaScript transform, which calculated the fahrenheit value from "temperatureCelsius" in the source_payload field and updated the temperature_fahrenheit field.

 "data": [
    {
      "source_payload": { "temperatureCelsius": 20 },
      "temperature_fahrenheit": 68,
      
      "create_ts": "2025-05-08T00:46:35.166",
      "changeId": 16128,
      "error": false,
      "log": null,
      "id": 1
    }
  ]