18F/C2

This cop looks for has_many or has_one associations that don't specify a :dependent option. It doesn't register an offense if :through option was specified.

Example:

# bad
class User < ActiveRecord::Base
  has_many :comments
  has_one :avatar
end

# good
class User < ActiveRecord::Base
  has_many :comments, dependent: :restrict_with_exception
  has_one :avatar, dependent: :destroy
  has_many :patients, through: :appointments
end

This cop checks for using Fixnum or Bignum constant.

Example:

# bad

1.is_a?(Fixnum)
1.is_a?(Bignum)

Example:

# good

1.is_a?(Integer)

This cop checks the indentation of the first element in an array literal where the opening bracket and the first element are on separate lines. The other elements' indentations are handled by the AlignArray cop.

By default, array literals that are arguments in a method call with parentheses, and where the opening square bracket of the array is on the same line as the opening parenthesis of the method call, shall have their first element indented one step (two spaces) more than the position inside the opening parenthesis.

Other array literals shall have their first element indented one step more than the start of the line where the opening square bracket is.

This default style is called 'specialinsideparentheses'. Alternative styles are 'consistent' and 'align_brackets'. Here are examples:

Example: EnforcedStyle: specialinsideparentheses (default)

# The `special_inside_parentheses` style enforces that the first
# element in an array literal where the opening bracket and first
# element are on seprate lines is indented one step (two spaces) more
# than the position inside the opening parenthesis.

#bad
array = [
  :value
]
and_in_a_method_call([
  :no_difference
                     ])

#good
array = [
  :value
]
but_in_a_method_call([
                       :its_like_this
                     ])

Example: EnforcedStyle: consistent

# The `consistent` style enforces that the first element in an array
# literal where the opening bracket and the first element are on
# seprate lines is indented the same as an array literal which is not
# defined inside a method call.

#bad
# consistent
array = [
  :value
]
but_in_a_method_call([
                       :its_like_this
])

#good
array = [
  :value
]
and_in_a_method_call([
  :no_difference
])

Example: EnforcedStyle: align_brackets

# The `align_brackets` style enforces that the opening and closing
# brackets are indented to the same position.

#bad
# align_brackets
and_now_for_something = [
                          :completely_different
]

#good
# align_brackets
and_now_for_something = [
                          :completely_different
                        ]

This cop checks for the formatting of empty method definitions. By default it enforces empty method definitions to go on a single line (compact style), but it can be configured to enforce the end to go on its own line (expanded style).

Note: A method definition is not considered empty if it contains comments.

Example: EnforcedStyle: compact (default)

# bad
def foo(bar)
end

def self.foo(bar)
end

# good
def foo(bar); end

def foo(bar)
  # baz
end

def self.foo(bar); end

Example: EnforcedStyle: expanded

# bad
def foo(bar); end

def self.foo(bar); end

# good
def foo(bar)
end

def self.foo(bar)
end

This cop looks for has_many or has_one associations that don't specify a :dependent option. It doesn't register an offense if :through option was specified.

Example:

# bad
class User < ActiveRecord::Base
  has_many :comments
  has_one :avatar
end

# good
class User < ActiveRecord::Base
  has_many :comments, dependent: :restrict_with_exception
  has_one :avatar, dependent: :destroy
  has_many :patients, through: :appointments
end

Use symbols as procs when possible.

Example:

# bad
something.map { |s| s.upcase }

# good
something.map(&:upcase)

Use symbols as procs when possible.

Example:

# bad
something.map { |s| s.upcase }

# good
something.map(&:upcase)

This cop can check for array literals made up of word-like strings, that are not using the %w() syntax.

Alternatively, it can check for uses of the %w() syntax, in projects which do not want to include that syntax.

Configuration option: MinSize If set, arrays with fewer elements than this value will not trigger the cop. For example, a MinSize of 3 will not enforce a style on an array of 2 or fewer elements.

Example: EnforcedStyle: percent (default)

# good
%w[foo bar baz]

# bad
['foo', 'bar', 'baz']

Example: EnforcedStyle: brackets

# good
['foo', 'bar', 'baz']

# bad
%w[foo bar baz]

This cop looks for has_many or has_one associations that don't specify a :dependent option. It doesn't register an offense if :through option was specified.

Example:

# bad
class User < ActiveRecord::Base
  has_many :comments
  has_one :avatar
end

# good
class User < ActiveRecord::Base
  has_many :comments, dependent: :restrict_with_exception
  has_one :avatar, dependent: :destroy
  has_many :patients, through: :appointments
end

This cop enforces the consistent usage of %-literal delimiters.

Specify the 'default' key to set all preferred delimiters at once. You can continue to specify individual preferred delimiters to override the default.

Example:

# Style/PercentLiteralDelimiters:
#   PreferredDelimiters:
#     default: '[]'
#     '%i':    '()'

# good
%w[alpha beta] + %i(gamma delta)

# bad
%W(alpha #{beta})

# bad
%I(alpha beta)

This cop checks for assignments in the conditions of if/while/until.

Example:

# bad

if some_var = true
  do_something
end

Example:

# good

if some_var == true
  do_something
end

This cop checks the indentation of the first element in an array literal where the opening bracket and the first element are on separate lines. The other elements' indentations are handled by the AlignArray cop.

By default, array literals that are arguments in a method call with parentheses, and where the opening square bracket of the array is on the same line as the opening parenthesis of the method call, shall have their first element indented one step (two spaces) more than the position inside the opening parenthesis.

Other array literals shall have their first element indented one step more than the start of the line where the opening square bracket is.

This default style is called 'specialinsideparentheses'. Alternative styles are 'consistent' and 'align_brackets'. Here are examples:

Example: EnforcedStyle: specialinsideparentheses (default)

# The `special_inside_parentheses` style enforces that the first
# element in an array literal where the opening bracket and first
# element are on seprate lines is indented one step (two spaces) more
# than the position inside the opening parenthesis.

#bad
array = [
  :value
]
and_in_a_method_call([
  :no_difference
                     ])

#good
array = [
  :value
]
but_in_a_method_call([
                       :its_like_this
                     ])

Example: EnforcedStyle: consistent

# The `consistent` style enforces that the first element in an array
# literal where the opening bracket and the first element are on
# seprate lines is indented the same as an array literal which is not
# defined inside a method call.

#bad
# consistent
array = [
  :value
]
but_in_a_method_call([
                       :its_like_this
])

#good
array = [
  :value
]
and_in_a_method_call([
  :no_difference
])

Example: EnforcedStyle: align_brackets

# The `align_brackets` style enforces that the opening and closing
# brackets are indented to the same position.

#bad
# align_brackets
and_now_for_something = [
                          :completely_different
]

#good
# align_brackets
and_now_for_something = [
                          :completely_different
                        ]

This cop enforces the use of either #alias or #alias_method depending on configuration. It also flags uses of alias :symbol rather than alias bareword.

Example: EnforcedStyle: prefer_alias (default)

# bad
alias_method :bar, :foo
alias :bar :foo

# good
alias bar foo

Example: EnforcedStyle: preferaliasmethod

# bad
alias :bar :foo
alias bar foo

# good
alias_method :bar, :foo

This cop enforces the consistent usage of %-literal delimiters.

Specify the 'default' key to set all preferred delimiters at once. You can continue to specify individual preferred delimiters to override the default.

Example:

# Style/PercentLiteralDelimiters:
#   PreferredDelimiters:
#     default: '[]'
#     '%i':    '()'

# good
%w[alpha beta] + %i(gamma delta)

# bad
%W(alpha #{beta})

# bad
%I(alpha beta)

This cop checks hash literal syntax.

It can enforce either the use of the class hash rocket syntax or the use of the newer Ruby 1.9 syntax (when applicable).

A separate offense is registered for each problematic pair.

The supported styles are:

• ruby19 - forces use of the 1.9 syntax (e.g. {a: 1}) when hashes have all symbols for keys
• hash_rockets - forces use of hash rockets for all hashes
• nomixedkeys - simply checks for hashes with mixed syntaxes
• ruby19nomixed_keys - forces use of ruby 1.9 syntax and forbids mixed syntax hashes

Example: EnforcedStyle: ruby19 (default)

# bad
{:a => 2}
{b: 1, :c => 2}

# good
{a: 2, b: 1}
{:c => 2, 'd' => 2} # acceptable since 'd' isn't a symbol
{d: 1, 'e' => 2} # technically not forbidden

Example: EnforcedStyle: hash_rockets

# bad
{a: 1, b: 2}
{c: 1, 'd' => 5}

# good
{:a => 1, :b => 2}

Example: EnforcedStyle: nomixedkeys

# bad
{:a => 1, b: 2}
{c: 1, 'd' => 2}

# good
{:a => 1, :b => 2}
{c: 1, d: 2}

Example: EnforcedStyle: ruby19nomixed_keys

# bad
{:a => 1, :b => 2}
{c: 2, 'd' => 3} # should just use hash rockets

# good
{a: 1, b: 2}
{:c => 3, 'd' => 4}

This cop checks that models subclass ApplicationRecord with Rails 5.0.

Example:

# good class Rails5Model < ApplicationRecord # ... end

# bad class Rails4Model < ActiveRecord::Base # ... end

This cop looks for has(one|many) and belongsto associations where ActiveRecord can't automatically determine the inverse association because of a scope or the options used. This can result in unnecessary queries in some circumstances. :inverse_of must be manually specified for associations to work in both ways, or set to false to opt-out.

Example:

# good
class Blog < ApplicationRecord
  has_many :posts
end

class Post < ApplicationRecord
  belongs_to :blog
end

Example:

# bad
class Blog < ApplicationRecord
  has_many :posts, -> { order(published_at: :desc) }
end

class Post < ApplicationRecord
  belongs_to :blog
end

# good
class Blog < ApplicationRecord
  has_many(:posts,
    -> { order(published_at: :desc) },
    inverse_of: :blog
  )
end

class Post < ApplicationRecord
  belongs_to :blog
end

# good
class Blog < ApplicationRecord
  with_options inverse_of: :blog do
    has_many :posts, -> { order(published_at: :desc) }
  end
end

class Post < ApplicationRecord
  belongs_to :blog
end

Example:

# bad
class Picture < ApplicationRecord
  belongs_to :imageable, polymorphic: true
end

class Employee < ApplicationRecord
  has_many :pictures, as: :imageable
end

class Product < ApplicationRecord
  has_many :pictures, as: :imageable
end

# good
class Picture < ApplicationRecord
  belongs_to :imageable, polymorphic: true
end

class Employee < ApplicationRecord
  has_many :pictures, as: :imageable, inverse_of: :imageable
end

class Product < ApplicationRecord
  has_many :pictures, as: :imageable, inverse_of: :imageable
end

Example:

# bad
# However, RuboCop can not detect this pattern...
class Physician < ApplicationRecord
  has_many :appointments
  has_many :patients, through: :appointments
end

class Appointment < ApplicationRecord
  belongs_to :physician
  belongs_to :patient
end

class Patient < ApplicationRecord
  has_many :appointments
  has_many :physicians, through: :appointments
end

# good
class Physician < ApplicationRecord
  has_many :appointments
  has_many :patients, through: :appointments
end

class Appointment < ApplicationRecord
  belongs_to :physician, inverse_of: :appointments
  belongs_to :patient, inverse_of: :appointments
end

class Patient < ApplicationRecord
  has_many :appointments
  has_many :physicians, through: :appointments
end

@see http://guides.rubyonrails.org/association_basics.html#bi-directional-associations @see http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html#module-ActiveRecord::Associations::ClassMethods-label-Setting+Inverses

This cop looks for has_many or has_one associations that don't specify a :dependent option. It doesn't register an offense if :through option was specified.

Example:

# bad
class User < ActiveRecord::Base
  has_many :comments
  has_one :avatar
end

# good
class User < ActiveRecord::Base
  has_many :comments, dependent: :restrict_with_exception
  has_one :avatar, dependent: :destroy
  has_many :patients, through: :appointments
end