Special Keywords

Last updated on May 30, 2023

Hevo provides the following keywords to help with creating advanced Transformations.

The $self Keyword

Use the variable $self to reference the value of the field on which the Transformation is being applied.

Sample Transformation

Scenario: if the value of the field isactive in the Event Type deals equals false, then, increase the price by 20%.

Here, you can use the $self variable as follows:

Event Type = deals

Event Field isactive = false
Fields = All fields with names = price

Enter value or formula = 1.2* $self

Using self keyword

Result: When you test the Transformation, the value of the price field is increased from 641 to 769:

The $null Keyword

The $null keyword can be used when you want to add fields or update existing field values with a null value. Since all null fields are dropped when Hevo ingests your data, you can create transformations with this keyword to include them again. Or, you may want to assign null values to fields based on some conditions rather than dropping them altogether.

The following sequence of two t\Transformations illustrate the usage of the $null field.

1. Change Field Value

For Event Type = shop and Event Field = price, change the value of price to $null. The field with its null value is not displayed in the test results.

Changing field value to null

2. Add a Field

Now, in the Events transformed in step 1 above, for Event Field = price and Event Field Value Is Null, add a field count with Value, Out-of-Stock. The transformation is applied successfully and can be verified in the results, confirming the behavior of the $null keyword.

The settings appear as follows:

null field settings

Result: The final output of the two Transformations appears as:

Add field based on a null field value

Revision History

Refer to the following table for the list of key updates made to this page:

Date Release Description of Change
Nov-25-2022 NA Created as a separate document.
Apr-25-2022 NA Updates the screenshots to reflect the latest UI.

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