FEATURE: Implement SiteSetting to Allow Anonymous Likes (#22131)

Allow anonymous users (logged-in, but set to anonymous posting) to like posts

---------

Co-authored-by: Emmett Ling <eling@zendesk.com>
Co-authored-by: Nat <natalie.tay@discourse.org>

app/serializers/post_serializer.rb

@@ -315,8 +315,14 @@ class PostSerializer < BasicPostSerializer
         summary.delete(:can_act)
       end
 
+      if actions.present? && SiteSetting.allow_anonymous_likes && sym == :like &&
+           !scope.can_delete_post_action?(actions[id])
+        summary.delete(:can_act)
+      end
+
       if actions.present? && actions.has_key?(id)
         summary[:acted] = true
+
         summary[:can_undo] = true if scope.can_delete?(actions[id])
       end
 

config/locales/server.en.yml

@@ -2164,6 +2164,7 @@ en:
     enable_category_group_moderation: "Allow groups to moderate content in specific categories"
     group_in_subject: "Set %%{optional_pm} in email subject to name of first group in PM, see: <a href='https://meta.discourse.org/t/customize-specific-email-templates/88323' target='_blank'>Customize subject format for standard emails</a>"
     allow_anonymous_posting: "Allow users to switch to anonymous mode"
+    allow_anonymous_likes: "Allow anonymous users to like posts"
     anonymous_posting_min_trust_level: "Minimum trust level required to enable anonymous posting"
     anonymous_account_duration_minutes: "To protect anonymity create a new anonymous account every N minutes for each user. Example: if set to 600, as soon as 600 minutes elapse from last post AND user switches to anon, a new anonymous account is created."
 

config/site_settings.yml

@@ -671,6 +671,9 @@ users:
   allow_anonymous_posting:
     default: false
     client: true
+  allow_anonymous_likes:
+    default: false
+    client: true
   anonymous_posting_min_trust_level:
     default: 1
     enum: "TrustLevelSetting"

lib/guardian.rb

@@ -620,10 +620,14 @@ class Guardian
   private
 
   def is_my_own?(obj)
-    unless anonymous?
-      return obj.user_id == @user.id if obj.respond_to?(:user_id) && obj.user_id && @user.id
-      return obj.user == @user if obj.respond_to?(:user)
+    if anonymous?
+      return(
+        SiteSetting.allow_anonymous_likes? && obj.class == PostAction && obj.is_like? &&
+          obj.user_id == @user.id
+      )
     end
+    return obj.user_id == @user.id if obj.respond_to?(:user_id) && obj.user_id && @user.id
+    return obj.user == @user if obj.respond_to?(:user)
 
     false
   end

lib/guardian/post_guardian.rb

@@ -43,7 +43,10 @@ module PostGuardian
     already_did_flagging = taken.any? && (taken & PostActionType.notify_flag_types.values).any?
 
     result =
-      if authenticated? && post && !@user.anonymous?
+      if authenticated? && post
+        # Allow anonymous users to like if feature is enabled and short-circuit otherwise
+        return SiteSetting.allow_anonymous_likes? && (action_key == :like) if @user.anonymous?
+
         # Silenced users can't flag
         return false if is_flag && @user.silenced?
 

spec/lib/guardian_spec.rb

@@ -98,6 +98,38 @@ RSpec.describe Guardian do
     fab!(:user) { Fabricate(:user) }
     fab!(:post) { Fabricate(:post) }
 
+    describe "an anonymous user" do
+      before { SiteSetting.allow_anonymous_posting = true }
+
+      context "when allow_anonymous_likes is enabled" do
+        before { SiteSetting.allow_anonymous_likes = true }
+
+        it "returns true when liking" do
+          expect(Guardian.new(anonymous_user).post_can_act?(post, :like)).to be_truthy
+        end
+
+        it "cannot perform any other action" do
+          expect(Guardian.new(anonymous_user).post_can_act?(post, :flag)).to be_falsey
+          expect(Guardian.new(anonymous_user).post_can_act?(post, :bookmark)).to be_falsey
+          expect(Guardian.new(anonymous_user).post_can_act?(post, :notify_user)).to be_falsey
+        end
+      end
+
+      context "when allow_anonymous_likes is disabled" do
+        before { SiteSetting.allow_anonymous_likes = false }
+
+        it "returns false when liking" do
+          expect(Guardian.new(anonymous_user).post_can_act?(post, :like)).to be_falsey
+        end
+
+        it "cannot perform any other action" do
+          expect(Guardian.new(anonymous_user).post_can_act?(post, :flag)).to be_falsey
+          expect(Guardian.new(anonymous_user).post_can_act?(post, :bookmark)).to be_falsey
+          expect(Guardian.new(anonymous_user).post_can_act?(post, :notify_user)).to be_falsey
+        end
+      end
+    end
+
     it "returns false when the user is nil" do
       expect(Guardian.new(nil).post_can_act?(post, :like)).to be_falsey
     end
@@ -2443,6 +2475,122 @@ RSpec.describe Guardian do
     end
   end
 
+  describe "#can_delete_post_action" do
+    before do
+      SiteSetting.allow_anonymous_posting = true
+      Guardian.any_instance.stubs(:anonymous?).returns(true)
+    end
+
+    context "with allow_anonymous_likes enabled" do
+      before { SiteSetting.allow_anonymous_likes = true }
+      describe "an anonymous user" do
+        let(:post_action) do
+          user.id = anonymous_user.id
+          post.id = 1
+
+          a =
+            PostAction.new(
+              user: anonymous_user,
+              post: post,
+              post_action_type_id: PostActionType.types[:like],
+            )
+          a.created_at = 1.minute.ago
+          a
+        end
+
+        let(:non_like_post_action) do
+          user.id = anonymous_user.id
+          post.id = 1
+
+          a =
+            PostAction.new(
+              user: anonymous_user,
+              post: post,
+              post_action_type_id: PostActionType.types[:reply],
+            )
+          a.created_at = 1.minute.ago
+          a
+        end
+
+        let(:other_users_post_action) do
+          user.id = user.id
+          post.id = 1
+
+          a =
+            PostAction.new(user: user, post: post, post_action_type_id: PostActionType.types[:like])
+          a.created_at = 1.minute.ago
+          a
+        end
+
+        it "returns true if the post belongs to the anonymous user" do
+          expect(Guardian.new(anonymous_user).can_delete_post_action?(post_action)).to be_truthy
+        end
+
+        it "return false if the post belongs to another user" do
+          expect(
+            Guardian.new(anonymous_user).can_delete_post_action?(other_users_post_action),
+          ).to be_falsey
+        end
+
+        it "returns false for any other action" do
+          expect(
+            Guardian.new(anonymous_user).can_delete_post_action?(non_like_post_action),
+          ).to be_falsey
+        end
+
+        it "returns false if the window has expired" do
+          post_action.created_at = 20.minutes.ago
+          SiteSetting.post_undo_action_window_mins = 10
+
+          expect(Guardian.new(anonymous_user).can_delete?(post_action)).to be_falsey
+        end
+      end
+    end
+
+    context "with allow_anonymous_likes disabled" do
+      before do
+        SiteSetting.allow_anonymous_likes = false
+        SiteSetting.allow_anonymous_posting = true
+      end
+      describe "an anonymous user" do
+        let(:post_action) do
+          user.id = anonymous_user.id
+          post.id = 1
+
+          a =
+            PostAction.new(
+              user: anonymous_user,
+              post: post,
+              post_action_type_id: PostActionType.types[:like],
+            )
+          a.created_at = 1.minute.ago
+          a
+        end
+
+        let(:non_like_post_action) do
+          user.id = anonymous_user.id
+          post.id = 1
+
+          a =
+            PostAction.new(
+              user: anonymous_user,
+              post: post,
+              post_action_type_id: PostActionType.types[:reply],
+            )
+          a.created_at = 1.minute.ago
+          a
+        end
+
+        it "any action returns false" do
+          expect(Guardian.new(anonymous_user).can_delete_post_action?(post_action)).to be_falsey
+          expect(
+            Guardian.new(anonymous_user).can_delete_post_action?(non_like_post_action),
+          ).to be_falsey
+        end
+      end
+    end
+  end
+
   describe "#can_see_deleted_posts?" do
     it "returns true if the user is an admin" do
       expect(Guardian.new(admin).can_see_deleted_posts?(post.topic.category)).to be_truthy

spec/serializers/post_serializer_spec.rb

@@ -310,6 +310,58 @@ RSpec.describe PostSerializer do
     end
   end
 
+  context "with allow_anonymous_likes enabled" do
+    fab!(:user) { Fabricate(:user) }
+    fab!(:topic) { Fabricate(:topic, user: user) }
+    fab!(:post) { Fabricate(:post, topic: topic, user: topic.user) }
+    fab!(:anonymous_user) { Fabricate(:anonymous) }
+
+    let(:serializer) { PostSerializer.new(post, scope: Guardian.new(anonymous_user), root: false) }
+    let(:post_action) do
+      user.id = anonymous_user.id
+      post.id = 1
+
+      a =
+        PostAction.new(
+          user: anonymous_user,
+          post: post,
+          post_action_type_id: PostActionType.types[:like],
+        )
+      a.created_at = 1.minute.ago
+      a
+    end
+
+    before do
+      SiteSetting.allow_anonymous_posting = true
+      SiteSetting.allow_anonymous_likes = true
+      SiteSetting.post_undo_action_window_mins = 10
+      PostSerializer.any_instance.stubs(:post_actions).returns({ 2 => post_action })
+    end
+
+    context "when post_undo_action_window_mins has not passed" do
+      before { post_action.created_at = 5.minutes.ago }
+
+      it "allows anonymous users to unlike posts" do
+        like_actions_summary =
+          serializer.actions_summary.find { |a| a[:id] == PostActionType.types[:like] }
+
+        #When :can_act is present, the JavaScript allows the user to click the unlike button
+        expect(like_actions_summary[:can_act]).to eq(true)
+      end
+    end
+
+    context "when post_undo_action_window_mins has passed" do
+      before { post_action.created_at = 20.minutes.ago }
+
+      it "disallows anonymous users from unliking posts" do
+        # There are no other post actions available to anonymous users so the action_summary will be an empty array
+        expect(serializer.actions_summary.find { |a| a[:id] == PostActionType.types[:like] }).to eq(
+          nil,
+        )
+      end
+    end
+  end
+
   describe "#user_status" do
     fab!(:user_status) { Fabricate(:user_status) }
     fab!(:user) { Fabricate(:user, user_status: user_status) }