Transformation Libraries

RudderStack’s transformation libraries feature lets you reuse the same code in multiple transformations.

RudderStack supports writing transformation libraries in Python for the RudderStack Cloud Growth and Enterprise plans.

Add transformation library

1. In the RudderStack dashboard, go to Collect > Transformations and click the Libraries tab. Then, click Create Library.

2. Add the library Name, Description and select the language to write the library function. You can also add multiple functions in a single library.

RudderStack supports Python libraries only in the RudderStack Cloud Growth and Enterprise plans.

3. Click Run Test to ensure the library code has the correct syntax. A Test Passed message pops up once the test runs successfully.

Use libraries in transformations

RudderStack provides some default libraries that you can import in your transformations for implementing various use cases like encrypting, decrypting, or hashing PII, parsing user agent, and using the localized version of Apple’s device mode information in your events.

See Default RudderStack libraries for more information.

To use the libraries in your existing transformations, note the library name listed in the Import library name column in the RudderStack dashboard:

RudderStack converts the library name into camel case without spaces; this becomes your library handle which you can use across multiple transformations. For example, if your library name is Sample Transformation Library, then the library handle would be sampleTransformationLibrary.

You can then use the library in a transformation with a simple import statement. Refer to the below use case for more information.

Use case

Suppose you want to filter the events that don’t contain an email address with the RudderStack domain. To do so, you can import a rudderEmail function from the transformation library isRudderEmail.

The rudderEmail function containing the filtering logic is shown below:

export function rudderEmail(email) {
    return /@(rudderlabs|rudderstack)| \+ruddertest/.test(email);
}

import re

def rudderEmail(email):
  match = re.search('@(rudderlabs|rudderstack)|\+ruddertest', email)
  if match:
    return True
  return False

The following snippets demonstrate how you can import this function in a transformation:

import { rudderEmail } from "isRudderEmail";
export function transformEvent(event) {
  const email =
    event.context && event.context.traits && event.context.traits.email;
  if (email) {
    if (!rudderEmail(email)) return;
  }
  return event;
}

from isRudderEmail import rudderEmail

def transformEvent(event, metadata):
    email = event.get("context", {}).get("traits", {}).get("email")
    if email:
        if not rudderEmail(email):
            return
    return event

On clicking Run Test, a sample event not containing the RudderStack email domain is filtered out:

Import multiple functions from single library

The following snippets highlight how to correctly import functions from a library:

// ---------------
import { getLoss } from "getFinanceData";

// OR

import { getLoss, getRevenue, getProfit } from "getFinanceData";
import {
  getLoss,
  getRevenue,
  getProfit
} from "getFinanceData";

// For default getPrice import
import getPrice, { getRevenue, getProfit } from "getFinanceData";

// alias imports
import getPrice as gp, { getRevenue as gr, getProfit } from "getFinanceData";
// usage: gp(event), gr(event), getProfit(ev)

import * as GFD from "getFinanceData";
// usage: GFD.getRevenue(ev), GFD.getProfit(ev)
// for default import: GFD.default(ev)

from getFinanceData import getRevenue, getProfit
// usage: getRevenue(event), getProfit(event)

from getFinanceData import getRevenue as gr, getProfit
// usage: gr(event), getProfit(ev)

import getFinanceData
// usage: getFinanceData.getRevenue(event), getFinanceData.getProfit(event)

The following snippets highlight the incorrect way of importing the library functions:

// -----------------
import * from "getFinanceData";
getPrice(ev)

// OR

import getPrice as gp from "getFinanceData";
getPrice(ev)

import getRevenue, getProfit from getFinanceData
import { getRevenue, getProfit } from getFinanceData

from getFinanceData import *

Delete library

You cannot delete a library that is referenced or imported in a transformation.

To delete a library, go to Collect > Transformations > Libraries and click the Delete button next to the library that you want to delete.

Default RudderStack libraries

By default, RudderStack provides four predefined libraries which you can directly import into your transformations. Refer to the GitHub codebase for the code and implementation-specific details for these libraries.

Currently, RudderStack libraries are available only for JavaScript. Python support (applicable for Growth/Enterprise customers) is coming soon.

Use the following structure to import the Rudderstack libraries:

@rs/<libraryname>/v1

A sample import statement is shown below:

import { JSEncrypt } from "@rs/encrypt/v1";

The following table lists the default RudderStack libraries and their usage:

FAQ

How can I use a npm package not provided by RudderStack in my transformations?

To use a different library (other than the default libraries provided by RudderStack) in your transformations:

1. Add a pure vanilla script as a transformation library.

All the imports and functions referenced in the code must have their implementation in the same file — essentially, a self-sufficient minified JavaScript implementation of the required package.

2. Import the library in your transformation.

Example

Suppose you want to use the blueimp/JavaScript-MD5 library to hash your PII.

1. Your MD5 function looks as follows:

! function(n) {"use strict";function d(n, t) {var r = (65535 & n) + (65535 & t);return (n >> 16) + (t >> 16) + (r >> 16) << 16 | 65535 & r} ... ... module.exports = t : n.md5 = t}(this);

For this example, note that:

• The min.js file is readily available — hence no other action is required. Otherwise, you will need to write a .js file separately.

• The method used as the entry point method is md5 and it uses the MD5 (hexadecimal), MD5 (raw), HMAC-MD5 (hexadecimal), and HMAC-MD5 (raw) functions — make sure to include these function implementations in the file.

  • The above functions may also reference other methods — make sure to include their implementations in the file, and so on.

• Include only minimal and relevant code in the file to avoid performance issues.

2. Add the above code in a new transformation library, for example, md5Library.
3. Import the above library in your transformation to hash sensitive PII:

// Import the MD5 function from your library
// Assuming the library handle is 'md5Library'

import { md5 } from "md5Library";

export function transformEvent(event) {
  // Get email from event properties
  const email = event.properties?.email;
  
  if (email) {
    // Hash the email using MD5
    event.properties.email = md5(email);
  }
  
  return event;
}

This transformation will hash any email address in the event properties using the provided MD5 algorithm.

Questions? Contact us by email or on Slack