Best practices

Below we haved listed some of the practices we follow for every Rails project. We also rely on multiple code analysers such as:

Views

Never use local variables on views
Refactor views by using partials
Don't use instance variables on partials, use local variables instead.
Never use instance variables for helpers. Pass local variables to the method

Models

Encapsulate complex queries into the models
Choose to include the method inverse_of in your models to save yourself from headaches.
Abstain from bypassing validations with methods like save(validate: false), update_attribute or toggle
Validate the associated belongs_to object (user), not the database column (user_id).
Favor in use of find over where when you need to retrieve a single record (whether by id or some attributes)

## Controllers

Try to keep your controller actions with one instance variable.
Never instantiate more than one object on a controller
Keep the controllers skinny they shouldn't contain any business logic

## Migrations

Name your migrations to start with a verb AddEmailToUsers
Set the default value to an empty string on non-required strings and text types.
Set a default value for boolean types.
Add null constraint where necessary, specially on booleans.
Default values should be declared on the migrations not the models.
Add foreign key constraints in migrations.

Routes

Avoid nesting routes more than one level depth (they can quickly become cumbersome). If you don't have any other option you can use shallow nesting to evade deep nesting

Misc

Choose decorators over helpers when your project is likely to widen
Choose Date.current over Date.today
Try to keep your classes no more than 100 lines long
Try to keep your methods no more than 5 lines long
Use the _url suffix for email templates routes and redirects. Otherwise use the _path suffix.
Keep the db/seed always with up to date data to run the project.