Understanding unique_index Use in Elixir for Business Logic

Herminio Torres discusses a common problem in building applications with business logic that involves unique constraints with databases. In the context of a conference ticketing system, Torres explores how to apply Elixir's Ecto schema's unique indexes to enforce that a user can only have one paid ticket but can acquire multiple tickets if they are free. Torres demonstrates how to create a unique index on the tickets table, scoped by the status in Ecto migrations. The article progresses to illustrate how to test this business logic with practical Elixir code examples in IEx. It is a technical piece that provides solutions for utilizing unique indexes to solve real-world problems with data integrity in Elixir-based applications.