AI: address review on PR #468

backend/app/controllers/posts_controller.rb

@@ -314,7 +314,9 @@ class PostsController < ApplicationController
   def viewed
     return head :unauthorized unless current_user
 
-    current_user.viewed_posts << Post.find(params[:id])
+    UserPostView.create_or_find_by!(
+        user: current_user,
+        post: Post.find(params[:id]))
     head :no_content
   end
 

backend/app/models/post_implication.rb

@@ -8,7 +8,6 @@ class PostImplication < ApplicationRecord
   validates :parent_post_id, presence: true
 
   validate :parent_post_mustnt_be_itself
-  validate :parent_post_mustnt_create_cycle
 
   private
 
@@ -17,24 +16,4 @@ class PostImplication < ApplicationRecord
       errors.add :parent_post_id, '親投稿に同じ投稿を設定することはできません．'
     end
   end
-
-  def parent_post_mustnt_create_cycle
-    return if post_id.blank? || parent_post_id.blank?
-    return if errors[:parent_post_id].present?
-
-    ancestor_ids = Set.new
-    frontier_ids = [parent_post_id]
-
-    until frontier_ids.empty?
-      if frontier_ids.include?(post_id)
-        errors.add :parent_post_id, :invalid
-        return
-      end
-
-      ancestor_ids.merge(frontier_ids)
-      frontier_ids = PostImplication.where(post_id: frontier_ids)
-          .distinct.pluck(:parent_post_id)
-          .reject { ancestor_ids.include?(_1) }
-    end
-  end
 end

backend/spec/models/post_implication_spec.rb

@@ -48,47 +48,4 @@ RSpec.describe PostImplication, type: :model do
     expect(duplicate).not_to be_valid
     expect(duplicate.errors[:post_id]).to be_present
   end
-
-  it 'rejects a parent that would create a two-post cycle' do
-    described_class.create!(post: post_record, parent_post:)
-
-    implication = described_class.new(
-        post: parent_post, parent_post: post_record)
-
-    expect(implication).not_to be_valid
-    expect(implication.errors.of_kind?(:parent_post_id, :invalid)).to be true
-  end
-
-  it 'rejects a parent that would create a three-post cycle' do
-    ancestor_post = create(:post)
-    described_class.create!(post: post_record, parent_post:)
-    described_class.create!(post: parent_post, parent_post: ancestor_post)
-
-    implication = described_class.new(
-        post: ancestor_post, parent_post: post_record)
-
-    expect(implication).not_to be_valid
-    expect(implication.errors.of_kind?(:parent_post_id, :invalid)).to be true
-  end
-
-  it 'allows a parent with an ancestor when no cycle would result' do
-    ancestor_post = create(:post)
-    described_class.create!(post: parent_post, parent_post: ancestor_post)
-
-    implication = described_class.new(post: post_record, parent_post:)
-
-    expect(implication).to be_valid
-  end
-
-  it 'terminates when existing ancestors already contain a cycle' do
-    ancestor_post = create(:post)
-    described_class.create!(post: parent_post, parent_post: ancestor_post)
-    legacy_implication = described_class.new(
-        post: ancestor_post, parent_post:)
-    legacy_implication.save!(validate: false)
-
-    implication = described_class.new(post: post_record, parent_post:)
-
-    expect(implication).to be_valid
-  end
 end

backend/spec/requests/posts_spec.rb

@@ -2559,6 +2559,21 @@ RSpec.describe 'Posts API', type: :request do
 
       expect(user.reload.viewed?(post_record)).to be(true)
     end
+
+    it '204 and keeps one view on repeated requests' do
+      sign_in_as(user)
+
+      expect {
+        post "/posts/#{ post_record.id }/viewed"
+      }.to change(UserPostView, :count).by(1)
+      expect(response).to have_http_status(:no_content)
+
+      expect {
+        post "/posts/#{ post_record.id }/viewed"
+      }.not_to change(UserPostView, :count)
+      expect(response).to have_http_status(:no_content)
+      expect(user.reload.viewed?(post_record)).to be(true)
+    end
   end
 
   describe 'DELETE /posts/:id/viewed' do