Apply Rails/InverseOf rubocop rule

Not doing so has a few gotchas when working with relations, particularly
with records which are not stored in the database.

I'm excluding the related content file because it's got a very peculiar
relationship with itself: the `has_one :opposite_related_content` has no
inverse; the relation itself is its inverse. It's a false positive since
the inverse condition is true:

```
content.opposite_related_content.opposite_related_content.object_id ==
  content.object_id
```

.rubocop.yml

@@ -21,9 +21,6 @@ Rails/HasAndBelongsToMany:
 Rails/HasManyOrHasOneDependent:
   Enabled: true
 
-Rails/InverseOf:
-  Enabled: true
-
 Rails/SkipsModelValidations:
   Enabled: true
 

.rubocop_basic.yml

@@ -206,6 +206,11 @@ Rails/FindEach:
 Rails/HttpPositionalArguments:
   Enabled: true
 
+Rails/InverseOf:
+  Enabled: true
+  Exclude:
+    - "app/models/related_content.rb"
+
 Rails/NotNullColumn:
   Enabled: true
   Exclude:

app/models/budget/investment.rb

@@ -32,7 +32,7 @@ class Budget
     translates :description, touch: true
     include Globalizable
 
-    belongs_to :author, -> { with_hidden }, class_name: "User"
+    belongs_to :author, -> { with_hidden }, class_name: "User", inverse_of: :budget_investments
     belongs_to :heading
     belongs_to :group
     belongs_to :budget
@@ -44,8 +44,11 @@ class Budget
     has_many :valuator_group_assignments, dependent: :destroy
     has_many :valuator_groups, through: :valuator_group_assignments
 
-    has_many :comments, -> { where(valuation: false) }, as: :commentable
-    has_many :valuations, -> { where(valuation: true) }, as: :commentable, class_name: "Comment"
+    has_many :comments, -> { where(valuation: false) }, as: :commentable, inverse_of: :commentable
+    has_many :valuations, -> { where(valuation: true) },
+      as:         :commentable,
+      inverse_of: :commentable,
+      class_name: "Comment"
 
     has_many :tracker_assignments, dependent: :destroy
     has_many :trackers, through: :tracker_assignments

app/models/budget/phase.rb

@@ -12,8 +12,8 @@ class Budget
     include Sanitizable
 
     belongs_to :budget
-    belongs_to :next_phase, class_name: self.name
-    has_one :prev_phase, class_name: self.name, foreign_key: :next_phase_id
+    belongs_to :next_phase, class_name: self.name, inverse_of: :prev_phase
+    has_one :prev_phase, class_name: self.name, foreign_key: :next_phase_id, inverse_of: :next_phase
 
     validates_translation :summary, length: { maximum: SUMMARY_MAX_LENGTH }
     validates_translation :description, length: { maximum: DESCRIPTION_MAX_LENGTH }

app/models/comment.rb

@@ -30,7 +30,7 @@ class Comment < ApplicationRecord
   validate :comment_valuation, if: -> { valuation }
 
   belongs_to :commentable, -> { with_hidden }, polymorphic: true, counter_cache: true, touch: true
-  belongs_to :user, -> { with_hidden }
+  belongs_to :user, -> { with_hidden }, inverse_of: :comments
 
   before_save :calculate_confidence_score
 

app/models/concerns/documentable.rb

@@ -2,7 +2,7 @@ module Documentable
   extend ActiveSupport::Concern
 
   included do
-    has_many :documents, as: :documentable, dependent: :destroy
+    has_many :documents, as: :documentable, inverse_of: :documentable, dependent: :destroy
     accepts_nested_attributes_for :documents, allow_destroy: true
   end
 

app/models/concerns/flaggable.rb

@@ -2,7 +2,7 @@ module Flaggable
   extend ActiveSupport::Concern
 
   included do
-    has_many :flags, as: :flaggable
+    has_many :flags, as: :flaggable, inverse_of: :flaggable
     scope :flagged, -> { where("flags_count > 0") }
     scope :pending_flag_review, -> { flagged.where(ignored_flag_at: nil, hidden_at: nil) }
     scope :with_ignored_flag, -> { flagged.where.not(ignored_flag_at: nil).where(hidden_at: nil) }

app/models/concerns/followable.rb

@@ -2,7 +2,7 @@ module Followable
   extend ActiveSupport::Concern
 
   included do
-    has_many :follows, as: :followable, dependent: :destroy
+    has_many :follows, as: :followable, inverse_of: :followable, dependent: :destroy
     has_many :followers, through: :follows, source: :user
 
     scope :followed_by_user, ->(user) {

app/models/concerns/galleryable.rb

@@ -2,7 +2,7 @@ module Galleryable
   extend ActiveSupport::Concern
 
   included do
-    has_many :images, as: :imageable, dependent: :destroy
+    has_many :images, as: :imageable, inverse_of: :imageable, dependent: :destroy
     accepts_nested_attributes_for :images, allow_destroy: true, update_only: true
 
     def image_url(style)

app/models/concerns/imageable.rb

@@ -2,7 +2,7 @@ module Imageable
   extend ActiveSupport::Concern
 
   included do
-    has_one :image, as: :imageable, dependent: :destroy
+    has_one :image, as: :imageable, inverse_of: :imageable, dependent: :destroy
     accepts_nested_attributes_for :image, allow_destroy: true, update_only: true
 
     def image_url(style)

app/models/concerns/linkable.rb

@@ -2,7 +2,7 @@ module Linkable
   extend ActiveSupport::Concern
 
   included do
-    has_many :links, as: :linkable, dependent: :destroy
+    has_many :links, as: :linkable, inverse_of: :linkable, dependent: :destroy
     accepts_nested_attributes_for :links, allow_destroy: true
   end
 end

app/models/concerns/milestoneable.rb

@@ -2,11 +2,11 @@ module Milestoneable
   extend ActiveSupport::Concern
 
   included do
-    has_many :milestones, as: :milestoneable, dependent: :destroy
+    has_many :milestones, as: :milestoneable, inverse_of: :milestoneable, dependent: :destroy
 
     scope :with_milestones, -> { joins(:milestones).distinct }
 
-    has_many :progress_bars, as: :progressable
+    has_many :progress_bars, as: :progressable, inverse_of: :progressable
 
     acts_as_taggable_on :milestone_tags
 

app/models/concerns/relationable.rb

@@ -2,7 +2,10 @@ module Relationable
   extend ActiveSupport::Concern
 
   included do
-    has_many :related_contents, as: :parent_relationable, dependent: :destroy
+    has_many :related_contents,
+      as:         :parent_relationable,
+      inverse_of: :parent_relationable,
+      dependent:  :destroy
   end
 
   def find_related_content(relationable)

app/models/concerns/reportable.rb

@@ -2,7 +2,7 @@ module Reportable
   extend ActiveSupport::Concern
 
   included do
-    has_one :report, as: :process, dependent: :destroy
+    has_one :report, as: :process, inverse_of: :process, dependent: :destroy
     accepts_nested_attributes_for :report
   end
 

app/models/concerns/stats_versionable.rb

@@ -2,7 +2,7 @@ module StatsVersionable
   extend ActiveSupport::Concern
 
   included do
-    has_one :stats_version, as: :process
+    has_one :stats_version, as: :process, inverse_of: :process
   end
 
   def find_or_create_stats_version

app/models/dashboard/executed_action.rb

@@ -2,7 +2,7 @@ class Dashboard::ExecutedAction < ApplicationRecord
   belongs_to :proposal
   belongs_to :action
 
-  has_many :administrator_tasks, as: :source, dependent: :destroy
+  has_many :administrator_tasks, as: :source, inverse_of: :source, dependent: :destroy
 
   validates :proposal, presence: true, uniqueness: { scope: :action }
   validates :action, presence: true

app/models/debate.rb

@@ -24,9 +24,9 @@ class Debate < ApplicationRecord
   translates :description, touch: true
   include Globalizable
 
-  belongs_to :author, -> { with_hidden }, class_name: "User"
+  belongs_to :author, -> { with_hidden }, class_name: "User", inverse_of: :debates
   belongs_to :geozone
-  has_many :comments, as: :commentable
+  has_many :comments, as: :commentable, inverse_of: :commentable
 
   extend DownloadSettings::DebateCsv
   delegate :name, :email, to: :author, prefix: true

app/models/direct_message.rb

@@ -1,6 +1,6 @@
 class DirectMessage < ApplicationRecord
-  belongs_to :sender,   class_name: "User"
-  belongs_to :receiver, class_name: "User"
+  belongs_to :sender,   class_name: "User", inverse_of: :direct_messages_sent
+  belongs_to :receiver, class_name: "User", inverse_of: :direct_messages_received
 
   validates :title,    presence: true
   validates :body,     presence: true

app/models/legislation/annotation.rb

@@ -5,9 +5,9 @@ class Legislation::Annotation < ApplicationRecord
 
   serialize :ranges, Array
 
-  belongs_to :draft_version, foreign_key: "legislation_draft_version_id"
+  belongs_to :draft_version, foreign_key: "legislation_draft_version_id", inverse_of: :annotations
   belongs_to :author, -> { with_hidden }, class_name: "User", inverse_of: :legislation_annotations
-  has_many :comments, as: :commentable, dependent: :destroy
+  has_many :comments, as: :commentable, inverse_of: :commentable, dependent: :destroy
 
   validates :text, presence: true
   validates :quote, presence: true

app/models/legislation/draft_version.rb

@@ -9,8 +9,11 @@ class Legislation::DraftVersion < ApplicationRecord
   translates :body,      touch: true
   include Globalizable
 
-  belongs_to :process, foreign_key: "legislation_process_id"
-  has_many :annotations, foreign_key: "legislation_draft_version_id", dependent: :destroy
+  belongs_to :process, foreign_key: "legislation_process_id", inverse_of: :draft_versions
+  has_many :annotations,
+    foreign_key: "legislation_draft_version_id",
+    inverse_of:  :draft_version,
+    dependent:   :destroy
 
   validates_translation :title, presence: true
   validates_translation :body, presence: true

app/models/legislation/people_proposal.rb

@@ -19,9 +19,9 @@ class Legislation::PeopleProposal < ApplicationRecord
   acts_as_votable
   acts_as_paranoid column: :hidden_at
 
-  belongs_to :process, foreign_key: "legislation_process_id"
-  belongs_to :author, -> { with_hidden }, class_name: "User"
-  has_many :comments, as: :commentable
+  belongs_to :process, foreign_key: "legislation_process_id", inverse_of: :people_proposals
+  belongs_to :author, -> { with_hidden }, class_name: "User", inverse_of: :people_proposals
+  has_many :comments, as: :commentable, inverse_of: :commentable
 
   validates :title, presence: true
   validates :summary, presence: true

app/models/legislation/process.rb

@@ -25,13 +25,26 @@ class Legislation::Process < ApplicationRecord
 
   CSS_HEX_COLOR = /\A#?(?:[A-F0-9]{3}){1,2}\z/i
 
-  has_many :draft_versions, -> { order(:id) }, foreign_key: "legislation_process_id", dependent: :destroy
+  has_many :draft_versions, -> { order(:id) },
+    foreign_key: "legislation_process_id",
+    inverse_of:  :process,
+    dependent:   :destroy
   has_one :final_draft_version, -> { where final_version: true, status: "published" },
     class_name:  "Legislation::DraftVersion",
-                                           foreign_key: "legislation_process_id"
-  has_many :questions, -> { order(:id) }, foreign_key: "legislation_process_id", dependent: :destroy
-  has_many :proposals, -> { order(:id) }, foreign_key: "legislation_process_id", dependent: :destroy
-  has_many :people_proposals, -> { order(:id) }, foreign_key: "legislation_process_id", dependent: :destroy
+    foreign_key: "legislation_process_id",
+    inverse_of:  :process
+  has_many :questions, -> { order(:id) },
+    foreign_key: "legislation_process_id",
+    inverse_of:  :process,
+    dependent:   :destroy
+  has_many :proposals, -> { order(:id) },
+    foreign_key: "legislation_process_id",
+    inverse_of:  :process,
+    dependent:   :destroy
+  has_many :people_proposals, -> { order(:id) },
+    foreign_key: "legislation_process_id",
+    inverse_of:  :process,
+    dependent:   :destroy
 
   validates_translation :title, presence: true
   validates :start_date, presence: true

app/models/legislation/proposal.rb

@@ -19,10 +19,10 @@ class Legislation::Proposal < ApplicationRecord
   acts_as_votable
   acts_as_paranoid column: :hidden_at
 
-  belongs_to :process, foreign_key: "legislation_process_id"
+  belongs_to :process, foreign_key: "legislation_process_id", inverse_of: :proposals
   belongs_to :author, -> { with_hidden }, class_name: "User", inverse_of: :legislation_proposals
   belongs_to :geozone
-  has_many :comments, as: :commentable
+  has_many :comments, as: :commentable, inverse_of: :commentable
 
   validates :title, presence: true
   validates :summary, presence: true

app/models/legislation/question.rb

@@ -7,12 +7,12 @@ class Legislation::Question < ApplicationRecord
   include Globalizable
 
   belongs_to :author, -> { with_hidden }, class_name: "User", inverse_of: :legislation_questions
-  belongs_to :process, foreign_key: "legislation_process_id"
+  belongs_to :process, foreign_key: "legislation_process_id", inverse_of: :questions
 
   has_many :question_options, -> { order(:id) }, class_name: "Legislation::QuestionOption", foreign_key: "legislation_question_id",
                                                  dependent: :destroy, inverse_of: :question
   has_many :answers, class_name: "Legislation::Answer", foreign_key: "legislation_question_id", dependent: :destroy, inverse_of: :question
-  has_many :comments, as: :commentable, dependent: :destroy
+  has_many :comments, as: :commentable, inverse_of: :commentable, dependent: :destroy
 
   accepts_nested_attributes_for :question_options, reject_if: proc { |attributes| attributes.all? { |k, v| v.blank? } }, allow_destroy: true
 

app/models/newsletter.rb

@@ -1,5 +1,5 @@
 class Newsletter < ApplicationRecord
-  has_many :activities, as: :actionable
+  has_many :activities, as: :actionable, inverse_of: :actionable
 
   validates :subject, presence: true
   validates :segment_recipient, presence: true

app/models/poll.rb

@@ -24,7 +24,7 @@ class Poll < ApplicationRecord
   has_many :officer_assignments, through: :booth_assignments
   has_many :officers, through: :officer_assignments
   has_many :questions, inverse_of: :poll, dependent: :destroy
-  has_many :comments, as: :commentable
+  has_many :comments, as: :commentable, inverse_of: :commentable
   has_many :ballot_sheets
 
   has_and_belongs_to_many :geozones

app/models/poll/answer.rb

@@ -1,5 +1,5 @@
 class Poll::Answer < ApplicationRecord
-  belongs_to :question, -> { with_hidden }
+  belongs_to :question, -> { with_hidden }, inverse_of: :answers
   belongs_to :author, ->   { with_hidden }, class_name: "User", inverse_of: :poll_answers
 
   delegate :poll, :poll_id, to: :question

app/models/poll/officer.rb

@@ -3,7 +3,7 @@ class Poll
     belongs_to :user
     has_many :officer_assignments
     has_many :shifts
-    has_many :failed_census_calls, foreign_key: :poll_officer_id
+    has_many :failed_census_calls, foreign_key: :poll_officer_id, inverse_of: :poll_officer
 
     validates :user_id, presence: true, uniqueness: true
 

app/models/poll/pair_answer.rb

@@ -1,5 +1,5 @@
 class Poll::PairAnswer < ApplicationRecord
-  belongs_to :question, -> { with_hidden }
+  belongs_to :question, -> { with_hidden }, inverse_of: :pair_answers
   belongs_to :author, ->   { with_hidden }, class_name: "User", inverse_of: :poll_pair_answers
   belongs_to :answer_right, class_name: "Poll::Question::Answer"
   belongs_to :answer_left, class_name: "Poll::Question::Answer"

app/models/poll/partial_result.rb

@@ -1,7 +1,7 @@
 class Poll::PartialResult < ApplicationRecord
   VALID_ORIGINS = %w[web booth]
 
-  belongs_to :question, -> { with_hidden }
+  belongs_to :question, -> { with_hidden }, inverse_of: :partial_results
   belongs_to :author, ->   { with_hidden }, class_name: "User", inverse_of: :poll_partial_results
   belongs_to :booth_assignment
   belongs_to :officer_assignment

app/models/poll/question.rb

@@ -11,12 +11,15 @@ class Poll::Question < ApplicationRecord
   belongs_to :poll
   belongs_to :author, -> { with_hidden }, class_name: "User", inverse_of: :poll_questions
 
-  has_many :comments, as: :commentable
+  has_many :comments, as: :commentable, inverse_of: :commentable
   has_many :answers, class_name: "Poll::Answer"
-  has_many :question_answers, -> { order "given_order asc" }, class_name: "Poll::Question::Answer", dependent: :destroy
+  has_many :question_answers, -> { order "given_order asc" },
+    class_name: "Poll::Question::Answer",
+    inverse_of: :question,
+    dependent:  :destroy
   has_many :partial_results
   has_many :pair_answers
-  has_one :votation_type, as: :questionable
+  has_one :votation_type, as: :questionable, inverse_of: :questionable
   belongs_to :proposal
 
   attr_accessor :enum_type, :max_votes, :prioritization_type

app/models/proposal.rb

@@ -35,13 +35,13 @@ class Proposal < ApplicationRecord
   include Globalizable
   translation_class_delegate :retired_at
 
-  belongs_to :author, -> { with_hidden }, class_name: "User"
+  belongs_to :author, -> { with_hidden }, class_name: "User", inverse_of: :proposals
   belongs_to :geozone
-  has_many :comments, as: :commentable, dependent: :destroy
+  has_many :comments, as: :commentable, inverse_of: :commentable, dependent: :destroy
   has_many :proposal_notifications, dependent: :destroy
   has_many :dashboard_executed_actions, dependent: :destroy, class_name: "Dashboard::ExecutedAction"
   has_many :dashboard_actions, through: :dashboard_executed_actions, class_name: "Dashboard::Action"
-  has_many :polls, as: :related
+  has_many :polls, as: :related, inverse_of: :related
 
   extend DownloadSettings::ProposalCsv
   delegate :name, :email, to: :author, prefix: true

app/models/site_customization/page.rb

@@ -1,6 +1,9 @@
 class SiteCustomization::Page < ApplicationRecord
   VALID_STATUSES = %w[draft published]
-  has_many :cards, class_name: "Widget::Card", foreign_key: "site_customization_page_id"
+  has_many :cards,
+    class_name:  "Widget::Card",
+    foreign_key: "site_customization_page_id",
+    inverse_of:  :page
 
   translates :title,       touch: true
   translates :subtitle,    touch: true

app/models/topic.rb

@@ -6,7 +6,7 @@ class Topic < ApplicationRecord
   belongs_to :community
   belongs_to :author, -> { with_hidden }, class_name: "User", inverse_of: :topics
 
-  has_many :comments, as: :commentable
+  has_many :comments, as: :commentable, inverse_of: :commentable
 
   validates :title, presence: true
   validates :description, presence: true

app/models/user.rb

@@ -21,20 +21,29 @@ class User < ApplicationRecord
   has_one :lock
   has_many :flags
   has_many :identities, dependent: :destroy
-  has_many :debates, -> { with_hidden }, foreign_key: :author_id
-  has_many :proposals, -> { with_hidden }, foreign_key: :author_id
-  has_many :people_proposals, -> { with_hidden }, foreign_key: :author_id
+  has_many :debates, -> { with_hidden }, foreign_key: :author_id, inverse_of: :author
+  has_many :proposals, -> { with_hidden }, foreign_key: :author_id, inverse_of: :author
+  has_many :people_proposals, -> { with_hidden }, foreign_key: :author_id, inverse_of: :author
   has_many :activities
-  has_many :budget_investments, -> { with_hidden }, foreign_key: :author_id, class_name: "Budget::Investment"
+  has_many :budget_investments, -> { with_hidden },
+    class_name:  "Budget::Investment",
+    foreign_key: :author_id,
+    inverse_of:  :author
   has_many :budget_investment_change_logs,
     foreign_key: :author_id,
     inverse_of:  :author,
     class_name:  "Budget::Investment::ChangeLog"
-  has_many :comments, -> { with_hidden }
+  has_many :comments, -> { with_hidden }, inverse_of: :user
   has_many :failed_census_calls
   has_many :notifications
-  has_many :direct_messages_sent,     class_name: "DirectMessage", foreign_key: :sender_id
-  has_many :direct_messages_received, class_name: "DirectMessage", foreign_key: :receiver_id
+  has_many :direct_messages_sent,
+    class_name:  "DirectMessage",
+    foreign_key: :sender_id,
+    inverse_of:  :sender
+  has_many :direct_messages_received,
+    class_name:  "DirectMessage",
+    foreign_key: :receiver_id,
+    inverse_of:  :receiver
   has_many :legislation_answers, class_name: "Legislation::Answer", dependent: :destroy, inverse_of: :user
   has_many :follows
   has_many :budget_rol_assignments

app/models/votation_set_answer.rb

@@ -1,6 +1,6 @@
 class VotationSetAnswer < ApplicationRecord
   belongs_to :votation_type
-  belongs_to :author, -> { with_hidden }, class_name: "User"
+  belongs_to :author, -> { with_hidden }, class_name: "User", inverse_of: :votation_set_answers
 
   scope :by_author, -> (author) { where(author: author) }
 end

app/models/widget/card.rb

@@ -1,6 +1,9 @@
 class Widget::Card < ApplicationRecord
   include Imageable
-  belongs_to :page, class_name: "SiteCustomization::Page", foreign_key: "site_customization_page_id"
+  belongs_to :page,
+    class_name:  "SiteCustomization::Page",
+    foreign_key: "site_customization_page_id",
+    inverse_of:  :cards
 
   # table_name must be set before calls to 'translates'
   self.table_name = "widget_cards"