FIX: Correctly set categoryId on Composer model (#23934)

app/assets/javascripts/discourse/app/models/composer.js

@@ -824,7 +824,10 @@ const Composer = RestModel.extend({
     });
 
     // We set the category id separately for topic templates on opening of composer
-    this.set("categoryId", opts.categoryId || this.get("topic.category.id"));
+    this.set(
+      "categoryId",
+      opts.topicCategoryId || opts.categoryId || this.get("topic.category.id")
+    );
 
     if (!this.categoryId && this.creatingTopic) {
       const categories = this.site.categories;

app/assets/javascripts/discourse/app/services/composer.js

@@ -1455,10 +1455,6 @@ export default class ComposerService extends Service {
       this.model.set("title", opts.topicTitle);
     }
 
-    if (opts.topicCategoryId) {
-      this.model.set("categoryId", opts.topicCategoryId);
-    }
-
     if (opts.topicTags && this.site.can_tag_topics) {
       let tags = escapeExpression(opts.topicTags)
         .split(",")

spec/system/composer/category_templates_spec.rb

@@ -160,6 +160,77 @@ describe "Composer Form Templates", type: :system do
     sign_in user
   end
 
+  describe "discard draft modal" do
+    it "does not show the modal if there is no draft on a topic without a template" do
+      category_page.visit(category_no_template)
+      category_page.new_topic_button.click
+      composer.close
+      expect(composer).to be_closed
+    end
+
+    it "shows the modal if there is a draft on a topic without a template" do
+      category_page.visit(category_no_template)
+      category_page.new_topic_button.click
+      composer.fill_content("abc")
+      composer.close
+      expect(composer).to be_opened
+      expect(composer).to have_discard_draft_modal
+    end
+
+    it "does not show the modal if there is no draft on a topic with a topic template" do
+      category_page.visit(category_topic_template)
+      category_page.new_topic_button.click
+      composer.close
+      expect(composer).to be_closed
+    end
+
+    it "shows the modal if there is a draft on a topic with a topic template" do
+      category_page.visit(category_topic_template)
+      category_page.new_topic_button.click
+      composer.append_content(" some more content")
+      composer.close
+      expect(composer).to be_opened
+      expect(composer).to have_discard_draft_modal
+    end
+
+    it "does not show the modal if on a topic with a form template" do
+      category_page.visit(category_with_template_1)
+      category_page.new_topic_button.click
+      composer.close
+      expect(composer).to be_closed
+    end
+
+    context "when the default template has a topic template" do
+      SiteSetting.default_composer_category =
+        (
+          if SiteSetting.general_category_id != -1
+            SiteSetting.general_category_id
+          else
+            SiteSetting.uncategorized_category_id
+          end
+        )
+      let(:default_category) { Category.find(SiteSetting.default_composer_category) }
+
+      before { default_category.update!(topic_template: "Testing") }
+
+      it "does not show the modal if there is no draft" do
+        category_page.visit(default_category)
+        category_page.new_topic_button.click
+        composer.close
+        expect(composer).to be_closed
+      end
+
+      it "shows the modal if there is a draft" do
+        category_page.visit(default_category)
+        category_page.new_topic_button.click
+        composer.append_content(" some more content")
+        composer.close
+        expect(composer).to be_opened
+        expect(composer).to have_discard_draft_modal
+      end
+    end
+  end
+
   it "shows a textarea when no form template is assigned to the category" do
     category_page.visit(category_no_template)
     category_page.new_topic_button.click

spec/system/page_objects/components/composer.rb

@@ -10,6 +10,10 @@ module PageObjects
         page.has_css?("#{COMPOSER_ID}.open")
       end
 
+      def closed?
+        page.has_css?("#{COMPOSER_ID}.closed", visible: :all)
+      end
+
       def open_composer_actions
         find(".composer-action-title .btn").click
         self
@@ -30,6 +34,12 @@ module PageObjects
         self
       end
 
+      def append_content(content)
+        current_content = composer_input.value
+        composer_input.set(current_content + content)
+        self
+      end
+
       def fill_form_template_field(field, content)
         form_template_field(field).fill_in(with: content)
         self
@@ -90,6 +100,10 @@ module PageObjects
         find("#{COMPOSER_ID} .d-editor-preview-wrapper")
       end
 
+      def has_discard_draft_modal?
+        page.has_css?(".discard-draft-modal")
+      end
+
       def has_emoji_autocomplete?
         has_css?(AUTOCOMPLETE_MENU)
       end