Fix for server error on the tags page when the category doesn't have tags

app/controllers/tags_controller.rb

@@ -27,20 +27,27 @@ def category
     @tags = if params[:q].present?
               @tag_set.tags.search(params[:q])
             elsif params[:hierarchical].present?
-              @tag_set.tags_with_paths.order(:path)
+              @tag_set.with_paths(params[:no_excerpt])
             elsif params[:no_excerpt].present?
-              @tag_set.tags.where(excerpt: '').or(@tag_set.tags.where(excerpt: nil))
-                      .order(Arel.sql('COUNT(posts.id) DESC'))
+              @tag_set.tags.where(excerpt: ['', nil])
             else
-              @tag_set&.tags&.order(Arel.sql('COUNT(posts.id) DESC'))
+              @tag_set&.tags
             end
-    @count = @tags&.size || 0
+
     table = params[:hierarchical].present? ? 'tags_paths' : 'tags'
-    if @count.positive?
-      @tags = @tags.left_joins(:posts).group(Arel.sql("#{table}.id"))
-                   .select(Arel.sql("#{table}.*, COUNT(DISTINCT IF(posts.deleted = 0, posts.id, NULL)) AS post_count"))
-                   .paginate(per_page: 96, page: params[:page])
-    end
+
+    @tags = @tags&.left_joins(:posts)
+                 &.group(Arel.sql("#{table}.id"))
+                 &.select(Arel.sql("#{table}.*, COUNT(DISTINCT IF(posts.deleted = 0, posts.id, NULL)) AS post_count"))
+                 &.paginate(per_page: 96, page: params[:page])
+
+    @tags = if params[:hierarchical].present?
+              @tags&.order(:path)
+            else
+              @tags&.order(Arel.sql('COUNT(posts.id) DESC'))
+            end
+
+    @count = @tags&.length || 0
   end
 
   def show

app/models/tag_set.rb

@@ -13,4 +13,12 @@ def self.meta
   def self.main
     where(name: 'Main').first
   end
+
+  def with_paths(no_excerpt = false)
+    if no_excerpt
+      tags_with_paths.where(excerpt: ['', nil])
+    else
+      tags_with_paths
+    end
+  end
 end

db/scripts/create_tags_path_view.sql

@@ -1,4 +1,4 @@
-create view tags_paths as
+CREATE OR REPLACE VIEW tags_paths AS
 WITH RECURSIVE tag_path (id, created_at, updated_at, community_id, tag_set_id, wiki_markdown,
                          wiki, excerpt, parent_id, name, path) AS
                    (

test/fixtures/tag_sets.yml

@@ -5,3 +5,7 @@ main:
 meta:
   name: Meta
   community: sample
+
+empty:
+  name: 'Empty'
+  community: sample

test/fixtures/tags.yml

@@ -10,6 +10,7 @@ support:
 
 bug:
   name: bug
+  excerpt: use for bug reports
   community: sample
   tag_set: main
 

test/models/tag_set_test.rb

@@ -1,7 +1,18 @@
 require 'test_helper'
 
 class TagSetTest < ActiveSupport::TestCase
-  # test "the truth" do
-  #   assert true
-  # end
+  include CommunityRelatedHelper
+
+  test 'is community related' do
+    assert_community_related(TagSet)
+  end
+
+  test 'with_paths method should respect no_excerpt' do
+    main = TagSet.main
+
+    all = main.with_paths.size
+    excerptless = main.with_paths(true).size
+
+    assert_not_equal(all, excerptless)
+  end
 end

test/test_helper.rb

@@ -25,6 +25,7 @@ class ActiveSupport::TestCase
   def load_fixtures(config)
     # Loading a fixture deletes all data in the same tables, so it has to happen before we load our normal seeds.
     fixture_data = super(config)
+    load_tags_paths
     load_seeds
 
     # We do need to return the same thing as the original method to not break fixtures
@@ -42,6 +43,10 @@ def load_seeds
     Rails.application.load_seed
   end
 
+  def load_tags_paths
+    ActiveRecord::Base.connection.execute File.read(Rails.root.join('db/scripts/create_tags_path_view.sql'))
+  end
+
   def clear_cache
     Rails.cache.clear
   end