FIX: Periodically ensure consistency of categories. (#7663)

app/jobs/scheduled/ensure_db_consistency.rb

@@ -21,6 +21,7 @@ module Jobs
       CategoryTagStat.ensure_consistency!
       User.ensure_consistency!
       UserAvatar.ensure_consistency!
+      Category.ensure_consistency!
     end
   end
 end

app/models/category.rb

@@ -664,6 +664,15 @@ class Category < ActiveRecord::Base
     end
   end
 
+  def self.ensure_consistency!
+    Category
+      .joins('LEFT JOIN topics ON categories.topic_id = topics.id AND topics.deleted_at IS NULL')
+      .where({ topics: { id: nil }})
+      .find_each do |category|
+      category.create_category_definition
+    end
+  end
+
   private
 
   def check_permissions_compatibility(parent_permissions, child_permissions)

lib/tasks/import.rake

@@ -428,7 +428,7 @@ end
 
 def create_category_definitions
   log "Creating category definitions"
-  Category.where(topic_id: nil).each(&:create_category_definition)
+  Category.ensure_consistency!
 end
 
 def log(message)

spec/models/category_spec.rb

@@ -890,4 +890,22 @@ describe Category do
     end
   end
 
+  describe "#ensure_consistency!" do
+    it "creates category topic" do
+      category = Fabricate(:category)
+      category_destroyed = Fabricate(:category)
+      category_trashed = Fabricate(:category)
+
+      category_topic_id = category.topic.id
+      category_destroyed.topic.destroy!
+      category_trashed.topic.trash!
+
+      Category.ensure_consistency!
+
+      expect(category.reload.topic_id).to eq(category_topic_id)
+      expect(category_destroyed.reload.topic).to_not eq(nil)
+      expect(category_trashed.reload.topic).to_not eq(nil)
+    end
+  end
+
 end