Support any number of tag intersections

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

@@ -43,7 +43,7 @@ export default Ember.Controller.extend(BulkTopicSelection, {
   needs: ["application"],
 
   tag: null,
-  secondaryTag: null,
+  additionalTags: null,
   list: null,
   canAdminTag: Ember.computed.alias("currentUser.staff"),
   filterMode: null,
@@ -73,8 +73,8 @@ export default Ember.Controller.extend(BulkTopicSelection, {
   }.property(),
 
   showAdminControls: function() {
-    return !this.get('secondaryTag') && this.get('canAdminTag') && !this.get('category');
-  }.property('secondaryTag', 'canAdminTag', 'category'),
+    return this.get('additionalTags') && this.get('canAdminTag') && !this.get('category');
+  }.property('additionalTags', 'canAdminTag', 'category'),
 
   loadMoreTopics() {
     return this.get("list").loadMore();

app/assets/javascripts/discourse/routes/app-route-map.js.es6

@@ -132,7 +132,7 @@ export default function() {
       this.route('showCategory' + filter.capitalize(), {path: '/c/:category/:tag_id/l/' + filter});
       this.route('showParentCategory' + filter.capitalize(), {path: '/c/:parent_category/:category/:tag_id/l/' + filter});
     });
-    this.route('show', {path: 'intersection/:tag_id/:secondary_tag_id'});
+    this.route('show', {path: 'intersection/:tag_id/*additional_tags'});
   });
 
   this.resource('tagGroups', {path: '/tag_groups'}, function() {

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

@@ -14,8 +14,11 @@ export default Discourse.Route.extend({
     var tag = this.store.createRecord("tag", { id: Handlebars.Utils.escapeExpression(params.tag_id) }),
         f = '';
 
-    if (params.secondary_tag_id) {
-      this.set("secondaryTag", this.store.createRecord("tag", { id: Handlebars.Utils.escapeExpression(params.secondary_tag_id) }));
+    if (params.additional_tags) {
+      this.set("additionalTags", _.compact(params.additional_tags.split('/')).map((tag) => {
+        return this.store.createRecord("tag", { id: Handlebars.Utils.escapeExpression(tag) });
+      }));
+      this.set("additionalTagIds", _.pluck(this.get("additionalTags"), 'id'));
     }
 
     if (params.category) {
@@ -50,7 +53,6 @@ export default Discourse.Route.extend({
     const parentCategorySlug = this.get('parentCategorySlug');
     const filter = this.get('navMode');
     const tag_id = (tag ? tag.id : 'none');
-    const secondary_tag_id = this.get('secondaryTag.id');
 
     if (categorySlug) {
       var category = Discourse.Category.findBySlug(categorySlug, parentCategorySlug);
@@ -61,8 +63,8 @@ export default Discourse.Route.extend({
       }
 
       this.set('category', category);
-    } else if (secondary_tag_id) {
-      params.filter = `tags/intersection/${tag_id}/${secondary_tag_id}`;
+    } else if (_.any(this.get("additionalTags"))) {
+      params.filter = `tags/intersection/${tag_id}/${this.get('additionalTagIds').join('/')}`;
       this.set('category', null);
     } else {
       params.filter = `tags/${tag_id}/l/${filter}`;
@@ -102,7 +104,7 @@ export default Discourse.Route.extend({
     this.controllerFor('tags.show').setProperties({
       model,
       tag: model,
-      secondaryTag: this.get('secondaryTag'),
+      additionalTags: this.get('additionalTags'),
       category: this.get('category'),
       filterMode: this.get('filterMode'),
       navMode: this.get('navMode'),
@@ -132,7 +134,7 @@ export default Discourse.Route.extend({
         // Pre-fill the tags input field
         if (controller.get('model.id')) {
           var c = self.controllerFor('composer').get('model');
-          c.set('tags', _.compact([controller.get('model.id'), controller.get('secondaryTag.id')]));
+          c.set('tags', _.flatten([controller.get('model.id')], controller.get('additionalTagIds')));
         }
       });
     },

app/assets/javascripts/discourse/templates/tags/show.hbs

@@ -5,7 +5,7 @@
 <div class="list-controls">
   <div class="container">
     {{#if tagNotification}}
-      {{#unless secondaryTag}}
+      {{#unless additionalTags}}
         {{tag-notifications-button action="changeTagNotification"
                                    notificationLevel=tagNotification.notification_level}}
       {{/unless}}
@@ -33,10 +33,10 @@
         {{#link-to 'tags'}}{{i18n "tagging.tags"}}{{/link-to}}
         {{fa-icon "angle-right"}}
         {{discourse-tag-bound tagRecord=tag style="simple"}}
-        {{#if secondaryTag}}
+        {{#each additionalTags as |tag|}}
           <span>&amp;</span>
-          {{discourse-tag-bound tagRecord=secondaryTag style="simple"}}
-        {{/if}}
+          {{discourse-tag-bound tagRecord=tag style="simple"}}
+        {{/each}}
       </h2>
     {{/if}}
   </div>