Ruby Developer Interview Questions for AI Training Work

Metaprogramming helps when it removes genuine repetition, like generating similar methods dynamically based on a schema, but it hurts maintainability when it obscures what methods actually exist, making the code harder to navigate and debug. I favor explicit code unless the repetition is significant enough to justify the readability cost.

I keep controllers thin, limited to orchestrating the request and response, and avoid putting complex business logic directly in models when it spans multiple models or has side effects beyond persistence. Service objects work well for that kind of cross-cutting logic, keeping models focused on their own data and validations.

I use eager loading with includes when I know upfront which associations a view will need, and I use tools like the Bullet gem in development to catch N+1 queries I might have missed. I'm cautious about eager loading associations that aren't actually used, since that trades one performance problem for another.

I keep the DSL's vocabulary close to the domain language users already understand, and I make sure error messages are clear when the DSL is used incorrectly, since a DSL that fails silently or with a cryptic Ruby error defeats the purpose of making the code more readable.

I read the upgrade guide for the specific version jump and use tools like the Rails upgrade checklist to identify deprecated features in the current codebase first. I run the existing test suite continuously through the upgrade process and upgrade dependencies incrementally rather than all at once.

I'd check for missing database indexes on frequently queried columns first, since that's a common cause of gradual degradation as table sizes grow, along with checking for N+1 queries that were tolerable at small scale but not anymore. I'd use query logs or an APM tool to find the actual slow queries rather than guessing.

I'd check all the places that model's methods and associations are used before making changes, and add tests covering existing behavior if coverage is thin. I'd prefer adding new methods over modifying existing ones where possible, to reduce the chance of an unexpected side effect elsewhere.

I'd check the gem's maintenance activity, open issues related to the Rails version we're on, and whether it has a reasonable test suite, since an unmaintained gem becomes a liability during future upgrades. I'd also weigh whether the functionality is simple enough to implement directly instead of adding a new dependency.

I built a dynamic attribute system using method_missing to reduce boilerplate, but it made the codebase much harder for new team members to understand, since methods didn't actually exist anywhere explicitly. I eventually refactored it to use explicit method definitions generated at load time, which kept the DRY benefit while making the code navigable.

A User model had accumulated authentication, billing, and notification logic over time. I extracted the billing and notification logic into separate service objects and concerns, keeping the User model focused on user-specific data and validations, which made both the model and the new objects easier to test independently.