Class: RuboCop::Cop::Rails::InverseOf

Inherits:
Cop
  • Object
show all
Extended by:
TargetRailsVersion
Defined in:
lib/rubocop/cop/rails/inverse_of.rb

Overview

This cop looks for has_(one|many) and belongs_to associations where Active Record can’t automatically determine the inverse association because of a scope or the options used. Using the blog with order scope example below, traversing the a Blog’s association in both directions with ‘blog.posts.first.blog` would cause the `blog` to be loaded from the database twice.

‘:inverse_of` must be manually specified for Active Record to use the associated object in memory, or set to `false` to opt-out. Note that setting `nil` does not stop Active Record from trying to determine the inverse automatically, and is not considered a valid value for this.

Examples:

# good
class Blog < ApplicationRecord
  has_many :posts
end

class Post < ApplicationRecord
  belongs_to :blog
end
# 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

# good
# When you don't want to use the inverse association.
class Blog < ApplicationRecord
  has_many(:posts,
    -> { order(published_at: :desc) },
    inverse_of: false
  )
end
# 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
# 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 Also:

Constant Summary collapse

SPECIFY_MSG = 
'Specify an `:inverse_of` option.'.freeze
NIL_MSG = 
'You specified `inverse_of: nil`, you probably meant to ' \
'use `inverse_of: false`.'.freeze

Constants included from Util

Util::ASGN_NODES, Util::CONDITIONAL_NODES, Util::EQUALS_ASGN_NODES, Util::LITERAL_REGEX, Util::LOGICAL_OPERATOR_NODES, Util::MODIFIER_NODES, Util::OPERATOR_METHODS, Util::SHORTHAND_ASGN_NODES

Instance Attribute Summary

Attributes inherited from Cop

#config, #corrections, #offenses, #processed_source

Instance Method Summary collapse

Methods included from TargetRailsVersion

minimum_target_rails_version, support_target_rails_version?

Methods inherited from Cop

#add_offense, all, autocorrect_incompatible_with, badge, #config_to_allow_offenses, #config_to_allow_offenses=, #cop_config, #cop_name, cop_name, #correct, department, #duplicate_location?, #excluded_file?, #find_location, #highlights, inherited, #initialize, #join_force?, lint?, match?, #messages, non_rails, #parse, qualified_cop_name, #relevant_file?, #target_rails_version, #target_ruby_version

Methods included from AST::Sexp

#s

Methods included from NodePattern::Macros

#def_node_matcher, #def_node_search, #node_search, #node_search_all, #node_search_body, #node_search_first

Methods included from AutocorrectLogic

#autocorrect?, #autocorrect_enabled?, #autocorrect_requested?, #support_autocorrect?

Methods included from IgnoredNode

#ignore_node, #ignored_node?, #part_of_ignored_node?

Methods included from Util

begins_its_line?, comment_line?, double_quotes_required?, escape_string, first_part_of_call_chain, interpret_string_escapes, line_range, needs_escaping?, on_node, operator?, parentheses?, same_line?, to_string_literal, to_supported_styles, tokens

Methods included from PathUtil

absolute?, match_path?, pwd, relative_path, reset_pwd, smart_path

Constructor Details

This class inherits a constructor from RuboCop::Cop::Cop

Instance Method Details

#on_send(node) ⇒ Object 



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# File 'lib/rubocop/cop/rails/inverse_of.rb', line 178

def on_send(node)
  recv, arguments = association_recv_arguments(node)
  return unless arguments
  with_options = with_options_arguments(recv, node)

  options = arguments.concat(with_options).flat_map do |arg|
    options_from_argument(arg)
  end
  return if options_ignoring_inverse_of?(options)

  return unless scope?(arguments) ||
                options_requiring_inverse_of?(options)

  return if options_contain_inverse_of?(options)
  add_offense(node, message: message(options), location: :selector)
end

#options_contain_inverse_of?(options) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/rubocop/cop/rails/inverse_of.rb', line 215

def options_contain_inverse_of?(options)
  options.any? { |opt| inverse_of_option?(opt) }
end

#options_ignoring_inverse_of?(options) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/rubocop/cop/rails/inverse_of.rb', line 209

def options_ignoring_inverse_of?(options)
  options.any? do |opt|
    through_option?(opt) || polymorphic_option?(opt)
  end
end

#options_requiring_inverse_of?(options) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/rubocop/cop/rails/inverse_of.rb', line 199

def options_requiring_inverse_of?(options)
  required = options.any? do |opt|
    conditions_option?(opt) ||
      foreign_key_option?(opt)
  end

  return required if target_rails_version >= 5.2
  required || options.any? { |opt| as_option?(opt) }
end

#same_context_in_with_options?(arg, recv) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/rubocop/cop/rails/inverse_of.rb', line 227

def same_context_in_with_options?(arg, recv)
  return true if arg.nil? && recv.nil?
  arg && recv && arg.children[0] == recv.children[0]
end

#scope?(arguments) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/rubocop/cop/rails/inverse_of.rb', line 195

def scope?(arguments)
  arguments.any?(&:block_type?)
end

#with_options_arguments(recv, node) ⇒ Object 



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# File 'lib/rubocop/cop/rails/inverse_of.rb', line 219

def with_options_arguments(recv, node)
  blocks = node.each_ancestor(:block).select do |block|
    block.send_node.command?(:with_options) &&
      same_context_in_with_options?(block.arguments.first, recv)
  end
  blocks.flat_map { |n| n.send_node.arguments }
end