Question 1

How do I use Mutations in a Rails controller for an API?

Accepted Answer

In a controller action, call the mutation's run method with params, check the outcome for success, and handle errors. For example, use outcome = UserSignup.run(params[:user]) and render JSON based on outcome.success? and outcome.errors, as shown in the README example.

Question 2

Mutations vs interactors in Ruby, which should I use?

Accepted Answer

Mutations provides a more structured framework with built-in validation and error handling, ideal for explicit command patterns. Interactors, like in the Interactor gem, focus on organizing business logic into actions but often require manual validation setup. Choose Mutations for validation-heavy commands and Interactors for simpler service orchestration.

Question 3

Can Mutations handle nested attributes or complex data structures?

Accepted Answer

Yes, Mutations supports nested hashes and arrays in its input definitions, as shown in the optional hash example for preferences. This allows handling complex data, but it requires declarative setup and doesn't automatically map to ActiveRecord nested attributes.

Question 4

How to test Mutations commands effectively in RSpec?

Accepted Answer

Test mutations by calling run with various inputs and asserting on outcome.result and outcome.errors. Since commands are isolated, you can write unit tests that mock dependencies, making testing straightforward and focused on business logic.

Question 5

Is Mutations compatible with background jobs like Sidekiq?

Accepted Answer

Yes, Mutations commands are reusable and don't depend on request context, so you can call them from background jobs. Just pass the necessary inputs as hashes, and handle errors appropriately in the job logic.

Question 6

How to share validation logic between multiple Mutations?

Accepted Answer

Use Ruby modules to encapsulate common validation rules and include them in multiple mutations. The README recommends composition over subclassing, so create modules for shared validations and mix them in as needed.

Question 7

What's the performance overhead of using Mutations?

Accepted Answer

Mutations adds overhead for input validation and coercion, but for most applications, this is minimal compared to database or network operations. In high-throughput scenarios, profile the validation steps, as the declarative checks can introduce latency if overused.

Mutations

What is Mutations?

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