FIX: You shouldn't be able to add a parent to Uncategorized

app/assets/javascripts/discourse/controllers/edit-category.js.es6

@@ -23,6 +23,8 @@ export default Discourse.ObjectController.extend(Discourse.ModalFunctionality, {
     return Discourse.Category.list().filterBy('parent_category_id', this.get('id'));
   }.property('model.id'),
 
+  canSelectParentCategory: Em.computed.not('isUncategorizedCategory'),
+
   onShow: function() {
     this.changeSize();
     this.titleChanged();

app/assets/javascripts/discourse/templates/modal/edit-category-general.js.handlebars

@@ -4,17 +4,19 @@
     {{text-field value=name placeholderKey="category.name_placeholder" maxlength="50"}}
   </section>
 
-  <section class='field'>
-    {{#if subCategories}}
-      <label>{{i18n categories.subcategories}}</label>
-      {{#each subCategories}}
-        {{category-badge this}}
-      {{/each}}
-    {{else}}
-      <label>{{i18n category.parent}}</label>
-      {{category-chooser valueAttribute="id" value=parent_category_id categories=parentCategories rootNone=true}}
-    {{/if}}
-  </section>
+  {{#if canSelectParentCategory}}
+    <section class='field'>
+      {{#if subCategories}}
+        <label>{{i18n categories.subcategories}}</label>
+        {{#each subCategories}}
+          {{category-badge this}}
+        {{/each}}
+      {{else}}
+        <label>{{i18n category.parent}}</label>
+        {{category-chooser valueAttribute="id" value=parent_category_id categories=parentCategories rootNone=true}}
+      {{/if}}
+    </section>
+  {{/if}}
 
   {{#if showDescription}}
     <section class='field'>

app/models/category.rb

@@ -198,7 +198,8 @@ SQL
 
   def parent_category_validator
     if parent_category_id
-      errors.add(:parent_category_id, I18n.t("category.errors.self_parent")) if parent_category_id == id
+      errors.add(:base, I18n.t("category.errors.self_parent")) if parent_category_id == id
+      errors.add(:base, I18n.t("category.errors.uncategorized_parent")) if uncategorized?
 
       grandfather_id = Category.where(id: parent_category_id).pluck(:parent_category_id).first
       errors.add(:base, I18n.t("category.errors.depth")) if grandfather_id

config/locales/server.en.yml

@@ -265,8 +265,9 @@ en:
     replace_paragraph: "[Replace this first paragraph with a short description of your new category. This guidance will appear in the category selection area, so try to keep it below 200 characters. Until you edit this text or create topics, this category won't appear on the categories page.]"
     post_template: "%{replace_paragraph}\n\nUse the following paragraphs for a longer description, as well as to establish any category guidelines or rules.\n\nSome things to consider in any discussion replies below:\n\n- What is this category for? Why should people select this category for their topic?\n\n- How is this different than the other categories we already have?\n\n- Do we need this category?\n\n- Should we merge this with another category, or split it into more categories?\n"
     errors:
-      self_parent: "A subcategory's parent cannot be itself."
-      depth: "You can't nest a subcategory under another."
+      uncategorized_parent: "Uncategorized can't have a parent category"
+      self_parent: "A subcategory's parent cannot be itself"
+      depth: "You can't nest a subcategory under another"
   trust_levels:
     newuser:
       title: "new user"

db/migrate/20140715190552_remove_uncategorized_parents.rb

@@ -0,0 +1,11 @@
+class RemoveUncategorizedParents < ActiveRecord::Migration
+  def up
+    uncat = execute("SELECT value FROM site_settings WHERE name = 'uncategorized_category_id'")
+    if uncat && uncat[0] && uncat[0]['value']
+      execute "UPDATE categories SET parent_category_id = NULL where id = #{uncat[0]['value'].to_i}"
+    end
+  end
+
+  def down
+  end
+end

spec/models/category_spec.rb

@@ -116,7 +116,7 @@ describe Category do
     end
 
     it "lists all secured categories correctly" do
-      uncategorized = Category.first
+      uncategorized = Category.find(SiteSetting.uncategorized_category_id)
 
       group.add(user)
       category.set_permissions(group.id => :full)
@@ -370,6 +370,19 @@ describe Category do
     end
   end
 
+  describe "uncategorized" do
+    let(:cat) { Category.where(id: SiteSetting.uncategorized_category_id).first }
+
+    it "reports as `uncategorized?`" do
+      cat.should be_uncategorized
+    end
+
+    it "cannot have a parent category" do
+      cat.parent_category_id = Fabricate(:category).id
+      cat.should_not be_valid
+    end
+  end
+
   describe "parent categories" do
     let(:user) { Fabricate(:user) }
     let(:parent_category) { Fabricate(:category, user: user) }