ADX 1-click now supports mapping transformations

Data format mappings (for example, Parquet, JSON, and Avro) in Azure Data Explorer now support simple and useful ingest-time transformations. In cases where the scenario requires more complex processing at ingest time, use the update policy, which will allow you to define lightweight processing using KQL expression. 

In addition, as part of a 1-click experience, you now have the ability to select data transformation logic from a supported list to add to one or more columns. 

To learn more, read about mapping transformations.