Improved public_for_api scopes and corresponding specs

config/initializers/acts_as_taggable_on.rb

@@ -21,7 +21,7 @@ module ActsAsTaggableOn
   Tag.class_eval do
 
     include Graphqlable
-    
+
     def increment_custom_counter_for(taggable_type)
       Tag.increment_counter(custom_counter_field_name_for(taggable_type), id)
     end
@@ -45,7 +45,20 @@ module ActsAsTaggableOn
     end
 
     def self.public_for_api
-      where("kind IS NULL OR kind = 'category'")
+      find_by_sql(%|
+        SELECT *
+        FROM tags
+        WHERE (tags.kind IS NULL OR tags.kind = 'category') AND tags.id IN (
+          SELECT tag_id
+          FROM (
+            SELECT COUNT(taggings.id) AS taggings_count, tag_id
+            FROM ((taggings FULL OUTER JOIN proposals ON taggable_type = 'Proposal' AND taggable_id = proposals.id) FULL OUTER JOIN debates ON taggable_type = 'Debate' AND taggable_id = debates.id)
+            WHERE (taggable_type = 'Proposal' AND proposals.hidden_at IS NULL) OR (taggable_type = 'Debate' AND debates.hidden_at IS NULL)
+            GROUP BY tag_id
+          ) AS tag_taggings_count_relation
+          WHERE taggings_count > 0
+        )
+      |)
     end
 
     private