FIX: Don't raise an error when post has been destroyed.

plugins/discourse-presence/plugin.rb

@@ -100,71 +100,75 @@ after_initialize do
     before_action :ensure_logged_in
 
     def publish
-      data = params.permit(:response_needed,
-              current: [:action, :topic_id, :post_id],
-              previous: [:action, :topic_id, :post_id]
-              )
+      data = params.permit(
+        :response_needed,
+        current: [:action, :topic_id, :post_id],
+        previous: [:action, :topic_id, :post_id]
+      )
 
-      if data[:previous] &&
-          data[:previous][:action].in?(['edit', 'reply'])
+      payload = {}
 
+      if data[:previous] && data[:previous][:action].in?(['edit', 'reply'])
         type = data[:previous][:post_id] ? 'post' : 'topic'
         id = data[:previous][:post_id] ? data[:previous][:post_id] : data[:previous][:topic_id]
 
         topic =
           if type == 'post'
-            Post.find_by(id: id).topic
+            Post.find_by(id: id)&.topic
           else
             Topic.find_by(id: id)
           end
 
-        guardian.ensure_can_see!(topic)
+        if topic
+          guardian.ensure_can_see!(topic)
 
-        any_changes = false
-        any_changes ||= Presence::PresenceManager.remove(type, id, current_user.id)
-        any_changes ||= Presence::PresenceManager.cleanup(type, id)
+          any_changes = false
+          any_changes ||= Presence::PresenceManager.remove(type, id, current_user.id)
+          any_changes ||= Presence::PresenceManager.cleanup(type, id)
 
-        users = Presence::PresenceManager.publish(type, id) if any_changes
+          users = Presence::PresenceManager.publish(type, id) if any_changes
+        end
       end
 
-      if data[:current] &&
-          data[:current][:action].in?(['edit', 'reply'])
-
+      if data[:current] && data[:current][:action].in?(['edit', 'reply'])
         type = data[:current][:post_id] ? 'post' : 'topic'
         id = data[:current][:post_id] ? data[:current][:post_id] : data[:current][:topic_id]
 
         topic =
           if type == 'post'
-            Post.find_by!(id: id).topic
+            Post.find_by(id: id)&.topic
           else
-            Topic.find_by!(id: id)
+            Topic.find_by(id: id)
           end
 
-        guardian.ensure_can_see!(topic)
+        if topic
+          guardian.ensure_can_see!(topic)
 
-        any_changes = false
-        any_changes ||= Presence::PresenceManager.add(type, id, current_user.id)
-        any_changes ||= Presence::PresenceManager.cleanup(type, id)
+          any_changes = false
+          any_changes ||= Presence::PresenceManager.add(type, id, current_user.id)
+          any_changes ||= Presence::PresenceManager.cleanup(type, id)
 
-        users = Presence::PresenceManager.publish(type, id) if any_changes
+          users = Presence::PresenceManager.publish(type, id) if any_changes
 
-        if data[:response_needed]
-          users ||= Presence::PresenceManager.get_users(type, id)
+          if data[:response_needed]
+            users ||= Presence::PresenceManager.get_users(type, id)
 
-          serialized_users = users.map { |u| BasicUserSerializer.new(u, root: false) }
+            serialized_users = users.map { |u| BasicUserSerializer.new(u, root: false) }
 
-          messagebus_channel = Presence::PresenceManager.get_messagebus_channel(type, id)
+            messagebus_channel = Presence::PresenceManager.get_messagebus_channel(type, id)
 
-          render json: {
-            messagebus_channel: messagebus_channel,
-            messagebus_id: MessageBus.last_id(messagebus_channel),
-            users: serialized_users
-          }
-          return
+            {
+              messagebus_channel: messagebus_channel,
+              messagebus_id: MessageBus.last_id(messagebus_channel),
+              users: serialized_users
+            }
+          end
+        else
+          {}
         end
       end
 
-      render json: {}
+      render json: payload
     end
 
   end

plugins/discourse-presence/spec/requests/presence_controller_spec.rb

@@ -1,7 +1,6 @@
 require 'rails_helper'
 
-describe ::Presence::PresencesController, type: :request do
-
+describe ::Presence::PresencesController do
   before do
     SiteSetting.presence_enabled = true
   end
@@ -13,7 +12,7 @@ describe ::Presence::PresencesController, type: :request do
   let(:post1) { Fabricate(:post) }
   let(:post2) { Fabricate(:post) }
 
-  after(:each) do
+  after do
     $redis.del("presence:topic:#{post1.topic.id}")
     $redis.del("presence:topic:#{post2.topic.id}")
     $redis.del("presence:post:#{post1.id}")
@@ -36,7 +35,6 @@ describe ::Presence::PresencesController, type: :request do
     end
 
     it "uses guardian to secure endpoint" do
-      # Private message
       private_post = Fabricate(:private_message_post)
 
       post '/presence/publish.json', params: {
@@ -45,7 +43,6 @@ describe ::Presence::PresencesController, type: :request do
 
       expect(response.code.to_i).to eq(403)
 
-      # Secure category
       group = Fabricate(:group)
       category = Fabricate(:private_category, group: group)
       private_topic = Fabricate(:topic, category: category)
@@ -64,7 +61,7 @@ describe ::Presence::PresencesController, type: :request do
         }
       end
 
-      expect(messages.count).to eq (1)
+      expect(messages.count).to eq(1)
 
       data = JSON.parse(response.body)
 
@@ -80,7 +77,7 @@ describe ::Presence::PresencesController, type: :request do
         }
       end
 
-      expect(messages.count).to eq (1)
+      expect(messages.count).to eq(1)
 
       data = JSON.parse(response.body)
       expect(data).to eq({})
@@ -93,7 +90,7 @@ describe ::Presence::PresencesController, type: :request do
         }
       end
 
-      expect(messages.count).to eq (1)
+      expect(messages.count).to eq(1)
 
       messages = MessageBus.track_publish do
         post '/presence/publish.json', params: {
@@ -101,7 +98,7 @@ describe ::Presence::PresencesController, type: :request do
         }
       end
 
-      expect(messages.count).to eq (0)
+      expect(messages.count).to eq(0)
     end
 
     it "clears 'previous' state when supplied" do
@@ -116,7 +113,28 @@ describe ::Presence::PresencesController, type: :request do
         }
       end
 
-      expect(messages.count).to eq (3)
+      expect(messages.count).to eq(3)
+    end
+
+    describe 'when post has been deleted' do
+      it 'should return an empty response' do
+        post1.destroy!
+
+        post '/presence/publish.json', params: {
+          current: { compose_state: 'open', action: 'edit', post_id: post1.id }
+        }
+
+        expect(response.status).to eq(200)
+        expect(JSON.parse(response.body)).to eq({})
+
+        post '/presence/publish.json', params: {
+          current: { compose_state: 'open', action: 'edit', post_id: post2.id },
+          previous: { compose_state: 'open', action: 'edit', post_id: post1.id }
+        }
+
+        expect(response.status).to eq(200)
+        expect(JSON.parse(response.body)).to eq({})
+      end
     end
 
   end