Dev Tutorial: Adding PostgreSQL Persistence to a NestJS Choose-Your-Own-Adventure API

A developer series called 'Grimoire API' is building a choose-your-own-adventure backend using NestJS, with Part 2 focusing on data persistence across server restarts. The tutorial introduces PostgreSQL paired with TypeORM as the database layer, run locally via Docker Compose for easy setup and teardown. A PlayerProgress entity is created to track each user's current story page and XP, mapping directly to a database table through TypeORM decorators. Notably, the design deliberately omits a stored 'level' column, deriving it from XP at runtime to prevent data inconsistencies. The module wires everything together using NestJS's dependency injection pattern, making the player progress repository available through TypeOrmModule.forFeature.