FEATURE: improve error message when double liking (#23698)

If a user somehow is looking at an old version of the page and attempts
to like a post they already like. Display a more reasonable error message.

Previously we would display:

> You are not permitted to view the requested resource.

New error message is:

> Oops! You already performed this action. Can you try refreshing the page?

Triggering this error condition is very tricky, you need to stop the
message bus. A possible reason for it could be bad network connectivity.

config/locales/server.en.yml

@@ -336,6 +336,8 @@ en:
   reading_time: "Reading time"
   likes: "Likes"
 
+  action_already_performed: "Oops! You already performed this action. Can you try refreshing the page?"
+
   too_many_replies:
     one: "We're sorry, but new users are temporarily limited to %{count} reply in the same topic."
     other: "We're sorry, but new users are temporarily limited to %{count} replies in the same topic."

lib/post_action_creator.rb

@@ -80,17 +80,27 @@ class PostActionCreator
       @post_action_name,
       opts: {
         is_warning: @is_warning,
-        taken_actions: PostAction.counts_for([@post].compact, @created_by)[@post&.id],
+        taken_actions: taken_actions,
       },
     )
   end
 
+  def taken_actions
+    return @taken_actions if defined?(@taken_actions)
+    @taken_actions = PostAction.counts_for([@post].compact, @created_by)[@post&.id]
+  end
+
   def perform
     result = CreateResult.new
 
     if !post_can_act? || (@queue_for_review && !guardian.is_staff?)
       result.forbidden = true
+
+      if taken_actions&.keys&.include?(PostActionType.types[@post_action_name])
+        result.add_error(I18n.t("action_already_performed"))
+      else
         result.add_error(I18n.t("invalid_access"))
+      end
       return result
     end
 

spec/lib/post_action_creator_spec.rb

@@ -61,6 +61,12 @@ RSpec.describe PostActionCreator do
       expect(result.post_action.user).to eq(user)
       expect(result.post_action.post).to eq(post)
       expect(result.post_action.post_action_type_id).to eq(like_type_id)
+
+      # also test double like
+      result = PostActionCreator.new(user, post, like_type_id).perform
+      expect(result.success).not_to eq(true)
+      expect(result.forbidden).to eq(true)
+      expect(result.errors.full_messages.join).to eq(I18n.t("action_already_performed"))
     end
 
     it "notifies subscribers" do
@@ -172,7 +178,7 @@ RSpec.describe PostActionCreator do
       end
 
       it "hides the post when the flagger is a TL3 user and the poster is a TL0 user" do
-        result = PostActionCreator.create(user, post, :spam)
+        PostActionCreator.create(user, post, :spam)
 
         expect(post.hidden?).to eq(true)
       end
@@ -180,7 +186,7 @@ RSpec.describe PostActionCreator do
       it "does not hide the post if the setting is disabled" do
         SiteSetting.high_trust_flaggers_auto_hide_posts = false
 
-        result = PostActionCreator.create(user, post, :spam)
+        PostActionCreator.create(user, post, :spam)
 
         expect(post.hidden?).to eq(false)
       end
@@ -223,14 +229,14 @@ RSpec.describe PostActionCreator do
 
         it "succeeds with other flag action types" do
           freeze_time 10.seconds.from_now
-          spam_result = PostActionCreator.create(user, post, :spam)
+          _spam_result = PostActionCreator.create(user, post, :spam)
 
           expect(reviewable.reload.pending?).to eq(true)
         end
 
         it "fails when other flag action types are open" do
           freeze_time 10.seconds.from_now
-          spam_result = PostActionCreator.create(user, post, :spam)
+          _spam_result = PostActionCreator.create(user, post, :spam)
 
           inappropriate_result = PostActionCreator.create(Fabricate(:user), post, :inappropriate)
 
@@ -307,7 +313,7 @@ RSpec.describe PostActionCreator do
     it "hides the topic even if it has replies" do
       Fabricate(:post, topic: post.topic)
 
-      result = build_creator.perform
+      _result = build_creator.perform
 
       expect(post.topic.reload.visible?).to eq(false)
     end