Transformations

The data received from the Source system might, at times, not be suitable to be replicated to the Destination database or data warehouse as is. Using Transformations in Hevo, you can prepare the data in multiple ways before loading it to the Destination. Read Data Transformation to know more about scenarios where you may need to transform your data.

Note: For any Transformation that is applied on an Event, a maximum of 10,000 child Events can be generated.

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Writing the Transformation

You can design and apply transformations on Events and Event Types in two ways:

• Writing Python-based transformation script

• Using drag-and-drop transformation blocks provided by Hevo

To change the transformation method, click the icon in the Transformation canvas.

Note: You cannot use both methods in the same transformation. Also, transformation of one type cannot be converted to the other automatically. If you switch from one method to the other, you need to rewrite the transformation completely.

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Testing the Transformation

Once you write or modify your transformations, you can test these against real sample Events received by Hevo from your Source.

To view a sample Event:

1. Click the Select Event Type drop-down and select the Source Event Type on which you want to test the transformation.

   

2. Click GET SAMPLE to fetch an Event from the Event Type. This is just a sample Event for testing. No changes are applied till you DEPLOY the transformation.

3. Click TEST to test the transformation and view the results.

   

You can also test the transformation on a random sample Event not specific to any Event Type. You can even modify the sample Events to test the transformation for any edge case scenario.

Testing Transformations on failed Events

You can test any transformation you have written to resolve failed Events directly within the Transformation page.

To do this:

1. Click the Select Event Type drop-down.

2. Enable the Events not Loaded option to view only the Event Types with failed Events.

3. Select the required Event Type and click GET SAMPLE.

4. Click TEST.

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Deploying the Transformation

Once you have tested the transformation, click DEPLOY. The transformation is applied to all applicable incoming Events.

You can click RESET to return to the last deployed stage.

We would advise you to monitor the Failed Events for any failures due to the newly deployed code.

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Transformation Version History

Click the icon to view the history of all deployed transformations.

You can restore any past deployed transformation by selecting it and clicking RESTORE THIS VERSION. The version is restored in Draft state. You must click DEPLOY to finally deploy it.

It is advised that you test the restored transformation before you deploy it. The system warns you if you try to directly deploy it.

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• Articles in this section
  • Python Code-Based Transformations
    • Example - Splitting Nested Events into Multiple Events
    • API References
      • Event Object
      • TimeUtils
      • Utils
  • Drag and Drop Transformations
    • Transformations and Properties
    • Examples of Drag and Drop Transformations
  • Effect of Transformations on the Destination Table Structure
  • Transformation Reference
    • Datetime Field Values
    • Operators
    • Rounding Modes
    • Text Casing
    • Values and Formulas