Handling Custom Postgres Errors in Ecto Changesets

The article by Jakub Lambrych provides a comprehensive method for capturing custom Postgres (or any RDBMS) errors in Ecto changesets without raising exceptions. It discusses the importance of handling errors in one place to maintain clean Elixir code without using 'try/rescue' constructs. The method proposed involves disguising custom database errors as one of the constraint errors already implemented in the Postgres Ecto adapter. The article details two main steps: raising an error in the Postgres codebase with a PL/pgSQL trigger function and defining a corresponding constraint in the Ecto changeset to capture the error. This approach ensures that the errors are handled efficiently within the native Elixir functionalities and minimizes the maintenance burden.