Dynamic modules (forRoot/forRootAsync) — why?

Short Interview Answer

Configure providers at runtime (e.g., connection options) while keeping a clean static API for consumers.

Detailed Explanation

forRootAsync injects ConfigService. Return DynamicModule with module/providers/exports. Essential for libraries.

Example

TypeOrmModule.forRootAsync({ useFactory: (cfg) => ({...}), inject: [ConfigService] })