The Repository Pattern Done Right: Consumer-Defined Interfaces in Go

The Repository Pattern We’ve all inherited it: a critical 500-line function with SQL Jenga blocks precariously placed between error handling, business logic, and an API call. You feel a natural instinct to refactor it, separate concerns; that’s the right call! However, the pattern most tutorials teach you to accomplish this just creates a different kind of mess. I’m talking about the repository pattern: an approach to separate your business layer (business logic) from your data layer (persistence and retrieval from a database). Understanding what drives this pattern - and where the standard implementation goes wrong - will permanently change how you structure database logic. The end result is maintainable, testable, and readable code. Martin Fowler describes this as mediating interaction, “… between the domain and data mapping layers using a collection-like interface.” Let’s break down what that actually means, and how it’s been so misinterpreted. The (short) theory The fundamentals ar