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Rails conventions

This is where we document how our Rails conventions deviate (or not) from the omakase stack.



Preferred libraries: SCSS (Sass) and CoffeeScript.


For breadcrumb builders.


Take HTTP input (params, cookies etc) and pass data to views. Not much else.

Very simple CRUD can be inline as in omakase Rails. Complexity should probably be moved into a model or interactor.

Shouldn't know SQL or much of the Active Record API; models should encapsulate that.

We like to pass locals explicitly to the view rather than using ivars.

Looking into: Two-step views (view objects and templates).


PDF document generators. E.g. ContractDocument.

Preferred library: see libs.


Excel or CSV generators. E.g. ContractsExcel.

Preferred library: see libs.


Rails-compatible form objects not backed by a DB, when we need them.

Preferred library: Minimapper::Entity.

Looking into: Maybe ActiveModel::Model in Rails 4?


As in omakase Rails, but we prefer presenters and view helpers (see below) if they're model-centric or complex enough that we want something more OO.

When convenient, a helper can delegate to a more OO implementation elsewhere.


Preferred library: Resque. Looking into: Sidekiq.

Job classes should be minimal, much like controllers.

Their responsibility is to configure themselves for retry handling, queues and such; and to parse and pass on parameters; but not much else.

The actual task to perform belongs in a model or interactor.


We like to use one mailer per action to facilitate refactoring. Action name: build. E.g. (ids for resque_mailer), wrapped in Buyer::WonItemMailer.deliver(item).


Minimapper mappers.


The active record models when using Minimapper. More about this layout.


Models don't have to inherit from ActiveRecord::Base. In fact, it's nice if they don't as they'll be easier to test.

Models never send mail (or similar) in callbacks. See interactors for that.

Did look into, but won't use in the future: Separating persistence from domain logic with Minimapper. With Minimapper, this is where the entity models go.


Avoid them. They're implicit model callbacks.

If possible, create an interactor instead.


For object-oriented helpers that wrap a single model.

Definitely use for things that involve both models and helpers (e.g. a due date wrapped in a CSS class).

Maybe use for localized strings based on non-localized state (e.g. turning "sold" state into "Sold item"). But putting that in the model may also be fine.

Do not use for domain concepts unless they involve HTML/CSS, localization or other front-end details. Calculating age from a birthdate column probably doesn't belong in a presenter. Put that in models or a general purpose library.

Preferred library: none, just POROs.

We like the view context to be passed in explicitly when needed, and for presenters to be clearly named as such in view variables instead of being seen as secret decorators. item_presenter, not item.


For models that are only used from the console for maintenance tasks that don't have a UI yet.

E.g. a ContractChanger.

Sort of like one-off scripts that are run often, but not often enough that we've made a proper UI.


For CarrierWave.


Also known as services or use cases. E.g. SignUpUser.from_params(params).

Use for:

  1. Representing interactions that involve persistence (via a model) and sending mail, like a user signup.
  2. More generally, to perform an action that doesn't go in the controller, because it's domain logic and not HTTP; nor in a model, because it is more of an interaction flow than just one action involving one or two models.

E.g. placing a bid in an eBay-like auction system, with max bids (that you place) and bids (that the system places on your behalf). It should be an interactor like and not a model method like Because it doesn't just involve that model and doesn't just deal with its internal concerns. It may create a record via that model, but may also create more than one Bid record and trigger mail notifications.

Interactors are high-level coordinators called by controllers, background jobs, scripts or other models.

They may communicate back to their caller by return value or callbacks on a passed-in object.

We name them VerbifyNoun and use .run for a method name if we can't come up with anything better.


For view-layer models.

Unlike presenters, these don't wrap a single model.

Can be things like a SearchTitle or ItemBreadcrumbBuilder.


Preferred library: Slim.


General purpose libraries that we or someone else couldn't bother to make into gems.

Aggressively extract general purpose code from models. We don't want to mix interesting domain specifics with general problems like figuring out banks from account numbers.



Preferred libraries: RSpec, Capybara.


Import scripts and such that are not suitable as regular migrations, because we run them repeatedly or not as part of a deploy.


Statistics generation scripts and data export scripts (that are run on a command line). Easier to find if separate from scripts/db.


Rails-free tests.

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