Rails-BelongsTo.md

Pattern: Use of deprecated required option

Issue: -

Description

This cop looks for belongs_to associations where we control whether the association is required via the deprecated required option instead.

Since Rails 5, belongs_to associations are required by default and this can be controlled through the use of optional: true.

From the release notes:

belongs_to will now trigger a validation error by default if the
association is not present. You can turn this off on a
per-association basis with optional: true. Also deprecate required
option in favor of optional for belongs_to. (Pull Request)

In the case that the developer is doing required: false, we definitely want to autocorrect to optional: true.

However, without knowing whether they've set overridden the default value of config.active_record.belongs_to_required_by_default, we can't say whether it's safe to remove required: true or whether we should replace it with optional: false (or, similarly, remove a superfluous optional: false). Therefore, in the cases we're using required: true, we'll simply invert it to optional: false and the user can remove depending on their defaults.

Examples

# bad
class Post < ApplicationRecord
  belongs_to :blog, required: false
end

# good
class Post < ApplicationRecord
  belongs_to :blog, optional: true
end

# bad
class Post < ApplicationRecord
  belongs_to :blog, required: true
end

# good
class Post < ApplicationRecord
  belongs_to :blog, optional: false
end

Further Reading

• RuboCop - Rails/BelongsTo