FIX: allow destination categories to be set if not at first

app/controllers/topics_controller.rb

@@ -240,10 +240,14 @@ class TopicsController < ApplicationController
   def update_shared_draft
     topic = Topic.find_by(id: params[:id])
     guardian.ensure_can_edit!(topic)
-    guardian.ensure_can_create_shared_draft!
-    raise Discourse::NotFound unless topic.shared_draft.present?
 
-    SharedDraft.where(topic_id: topic.id).update_all(category_id: params[:category_id].to_i)
+    category = Category.where(id: params[:category_id].to_i).first
+    guardian.ensure_can_publish_topic!(topic, category)
+
+    row_count = SharedDraft.where(topic_id: topic.id).update_all(category_id: category.id)
+    if row_count == 0
+      SharedDraft.create(topic_id: topic.id, category_id: category.id)
+    end
 
     render json: success_json
   end

spec/requests/topics_controller_spec.rb

@@ -465,31 +465,40 @@ RSpec.describe TopicsController do
     end
 
     describe "#update_shared_draft" do
-      let(:category) { Fabricate(:category) }
       let(:other_cat) { Fabricate(:category) }
+      let(:category) { Fabricate(:category) }
       let(:topic) { Fabricate(:topic, category: shared_drafts_category, visible: false) }
-      let!(:shared_draft) { Fabricate(:shared_draft, topic: topic, category: category) }
-      let(:moderator) { Fabricate(:moderator) }
 
       context "anonymous" do
         it "doesn't allow staff to update the shared draft" do
           put "/t/#{topic.id}/shared-draft.json", params: { category_id: other_cat.id }
           expect(response.code.to_i).to eq(403)
-          topic.reload
-          expect(topic.shared_draft.category_id).to eq(category.id)
         end
       end
 
       context "as a moderator" do
+        let(:moderator) { Fabricate(:moderator) }
         before do
           sign_in(moderator)
         end
 
-        it "allows staff to update the category id" do
+        context "with a shared draft" do
-          put "/t/#{topic.id}/shared-draft.json", params: { category_id: other_cat.id }
+          let!(:shared_draft) { Fabricate(:shared_draft, topic: topic, category: category) }
-          expect(response).to be_success
+          it "allows staff to update the category id" do
-          topic.reload
+            put "/t/#{topic.id}/shared-draft.json", params: { category_id: other_cat.id }
-          expect(topic.shared_draft.category_id).to eq(other_cat.id)
+            expect(response).to be_success
+            topic.reload
+            expect(topic.shared_draft.category_id).to eq(other_cat.id)
+          end
+        end
+
+        context "without a shared draft" do
+          it "allows staff to update the category id" do
+            put "/t/#{topic.id}/shared-draft.json", params: { category_id: other_cat.id }
+            expect(response).to be_success
+            topic.reload
+            expect(topic.shared_draft.category_id).to eq(other_cat.id)
+          end
         end
       end
     end