FEATURE: add filter to show topics that have not been tagged

app/assets/javascripts/discourse/components/tag-drop.js.es6

@@ -45,6 +45,20 @@ export default Ember.Component.extend({
     return I18n.t("tagging.selector_all_tags");
   }.property('tag'),
 
+  @computed('firstCategory', 'secondCategory')
+  noTagsUrl() {
+    var url = '/tags';
+    if (this.get('currentCategory')) {
+      url += this.get('currentCategory.url');
+    }
+    return url + '/none';
+  },
+
+  @computed('tag')
+  noTagsLabel() {
+    return I18n.t("tagging.selector_no_tags");
+  },
+
   dropdownButtonClass: function() {
     var result = 'badge-category category-dropdown-button';
     if (Em.isNone(this.get('tag'))) {

app/assets/javascripts/discourse/routes/tags-show.js.es6

@@ -11,7 +11,7 @@ export default Discourse.Route.extend({
   },
 
   model(params) {
-    var tag = this.store.createRecord("tag", { id: Handlebars.Utils.escapeExpression(params.tag_id) }),
+    var tag = (params.tag_id === 'none' ? null : this.store.createRecord("tag", { id: Handlebars.Utils.escapeExpression(params.tag_id) })),
         f = '';
 
     if (params.category) {
@@ -25,8 +25,8 @@ export default Discourse.Route.extend({
     if (params.category) { this.set('categorySlug', params.category); }
     if (params.parent_category) { this.set('parentCategorySlug', params.parent_category); }
 
-    if (this.get("currentUser")) {
+    if (tag && this.get("currentUser")) {
-      // If logged in, we should get the tag"s user settings
+      // If logged in, we should get the tag's user settings
       return this.store.find("tagNotification", tag.get("id")).then(tn => {
         this.set("tagNotification", tn);
         return tag;
@@ -45,18 +45,19 @@ export default Discourse.Route.extend({
     const categorySlug = this.get('categorySlug');
     const parentCategorySlug = this.get('parentCategorySlug');
     const filter = this.get('navMode');
+    const tag_id = (tag ? tag.id : 'none');
 
     if (categorySlug) {
       var category = Discourse.Category.findBySlug(categorySlug, parentCategorySlug);
       if (parentCategorySlug) {
-        params.filter = `tags/c/${parentCategorySlug}/${categorySlug}/${tag.id}/l/${filter}`;
+        params.filter = `tags/c/${parentCategorySlug}/${categorySlug}/${tag_id}/l/${filter}`;
       } else {
-        params.filter = `tags/c/${categorySlug}/${tag.id}/l/${filter}`;
+        params.filter = `tags/c/${categorySlug}/${tag_id}/l/${filter}`;
       }
 
       this.set('category', category);
     } else {
-      params.filter = `tags/${tag.id}/l/${filter}`;
+      params.filter = `tags/${tag_id}/l/${filter}`;
       this.set('category', null);
     }
 
@@ -74,11 +75,19 @@ export default Discourse.Route.extend({
     const filterText = I18n.t('filters.' + this.get('navMode').replace('/', '.') + '.title'),
           controller = this.controllerFor('tags.show');
 
+    if (controller.get('model.id')) {
       if (this.get('category')) {
         return I18n.t('tagging.filters.with_category', { filter: filterText, tag: controller.get('model.id'), category: this.get('category.name')});
       } else {
         return I18n.t('tagging.filters.without_category', { filter: filterText, tag: controller.get('model.id')});
       }
+    } else {
+      if (this.get('category')) {
+        return I18n.t('tagging.filters.untagged_with_category', { filter: filterText, category: this.get('category.name')});
+      } else {
+        return I18n.t('tagging.filters.untagged_without_category', { filter: filterText});
+      }
+    }
   },
 
   setupController(controller, model) {

app/assets/javascripts/discourse/templates/components/tag-drop.hbs

@@ -2,6 +2,7 @@
   {{#if tagId}}
     <a href {{action "expand"}} class="badge-category {{tagClass}}">{{tagId}}</a>
   {{else}}
+    <!-- TODO: how to detect "no tags" is currently selected -->
     <a href {{action "expand"}} class="badge-category {{tagClass}} home">{{allTagsLabel}}</a>
   {{/if}}
 
@@ -9,6 +10,7 @@
     <a href {{action "expand"}} class={{dropdownButtonClass}}><i class={{iconClass}}></i></a>
     <section class="{{unless expanded 'hidden'}} category-dropdown-menu chooser">
       <div class='cat'><a href={{allTagsUrl}} data-drop-close="true" class='badge-category home'>{{allTagsLabel}}</a></div>
+      <div class='cat'><a href={{noTagsUrl}}  data-drop-close="true" class='badge-category home'>{{noTagsLabel}}</a></div>
       {{#if renderTags}}
         {{#each tags as |t|}}
           <div class='cat'>

app/controllers/tags_controller.rb

@@ -57,7 +57,7 @@ class TagsController < ::ApplicationController
       @list.more_topics_url = list_by_tag_path(tag_id: @tag_id, page: page + 1)
       @rss = "tag"
 
-      if @list.topics.size == 0 && !Tag.where(name: @tag_id).exists?
+      if @list.topics.size == 0 && params[:tag_id] != 'none' && !Tag.where(name: @tag_id).exists?
         raise Discourse::NotFound
       else
         respond_with_list(@list)
@@ -203,7 +203,6 @@ class TagsController < ::ApplicationController
         topic_ids: param_to_integer_list(:topic_ids),
         exclude_category_ids: params[:exclude_category_ids],
         category: params[:category],
-        tags: [params[:tag_id]],
         order: params[:order],
         ascending: params[:ascending],
         min_posts: params[:min_posts],
@@ -217,6 +216,12 @@ class TagsController < ::ApplicationController
       options[:no_subcategories] = true if params[:no_subcategories] == 'true'
       options[:slow_platform] = true if slow_platform?
 
+      if params[:tag_id] == 'none'
+        options[:no_tags] = true
+      else
+        options[:tags] = [params[:tag_id]]
+      end
+
       options
     end
 

config/locales/client.en.yml

@@ -2123,6 +2123,7 @@ en:
     tagging:
       all_tags: "All Tags"
       selector_all_tags: "all tags"
+      selector_no_tags: "no tags"
       changed: "tags changed:"
       tags: "Tags"
       choose_for_topic: "choose optional tags for this topic"
@@ -2139,6 +2140,8 @@ en:
       filters:
         without_category: "%{filter} %{tag} topics"
         with_category: "%{filter} %{tag} topics in %{category}"
+        untagged_without_category: "%{filter} untagged topics"
+        untagged_with_category: "%{filter} untagged topics in %{category}"
 
       notifications:
         watching:

lib/topic_query.rb

@@ -20,6 +20,7 @@ class TopicQuery
                      visible
                      category
                      tags
+                     no_tags
                      order
                      ascending
                      no_subcategories
@@ -465,6 +466,9 @@ class TopicQuery
           else
             result = result.where("tags.name in (?)", @options[:tags])
           end
+        elsif @options[:no_tags]
+          # the following will do: ("topics"."id" NOT IN (SELECT DISTINCT "topic_tags"."topic_id" FROM "topic_tags"))
+          result = result.where.not(:id => TopicTag.select(:topic_id).uniq)
         end
       end
 

spec/components/topic_query_spec.rb

@@ -122,12 +122,14 @@ describe TopicQuery do
       SiteSetting.tagging_enabled = true
     end
 
-    it "returns topics with the tag when filtered to it" do
+    context "no category filter" do
-      tagged_topic1 = Fabricate(:topic, {tags: [tag]})
+      # create some topics before each test:
-      tagged_topic2 = Fabricate(:topic, {tags: [other_tag]})
+      let!(:tagged_topic1) { Fabricate(:topic, {tags: [tag]}) }
-      tagged_topic3 = Fabricate(:topic, {tags: [tag, other_tag]})
+      let!(:tagged_topic2) { Fabricate(:topic, {tags: [other_tag]}) }
-      no_tags_topic = Fabricate(:topic)
+      let!(:tagged_topic3) { Fabricate(:topic, {tags: [tag, other_tag]}) }
+      let!(:no_tags_topic) { Fabricate(:topic) }
 
+      it "returns topics with the tag when filtered to it" do
         expect(TopicQuery.new(moderator, tags: [tag.name]).list_latest.topics.map(&:id).sort).to eq([tagged_topic1.id, tagged_topic3.id].sort)
         expect(TopicQuery.new(moderator, tags: [tag.id]).list_latest.topics.map(&:id).sort).to eq([tagged_topic1.id, tagged_topic3.id].sort)
 
@@ -143,6 +145,11 @@ describe TopicQuery do
         # expect(TopicQuery.new(moderator, tags: [tag.id, other_tag.id]).list_latest.topics.map(&:id)).to eq([tagged_topic3.id].sort)
       end
 
+      it "can return topics with no tags" do
+        expect(TopicQuery.new(moderator, no_tags: true).list_latest.topics.map(&:id)).to eq([no_tags_topic.id])
+      end
+    end
+
     context "and categories too" do
       let(:category1) { Fabricate(:category) }
       let(:category2) { Fabricate(:category) }