Understanding Validation in the Ash Framework

This article explores how the Ash Framework facilitates validation through a mechanism known as the changeset pattern. A changeset encapsulates the value being validated, proposed changes, and accumulated errors, allowing for the validation of both state management and error tracking. The article discusses the use of predicates for validation, the construction of changesets, and the nuances between product types and sum types, particularly how Elixir handles state. It also highlights strategies for implementing conditional and state-aware validations, as well as the independence of validations—concisely explained through functional programming concepts like Either and Monads. Additionally, the discussion touches upon the concurrent validation of independent checks using the Effect context, contrasting Ash's approach to functional programming paradigms. The author concludes by addressing the strengths and weaknesses of Ash’s validation mechanism, emphasizing the balanced use of both Ash and functional validation for complex validation pipelines.