Now default tags can be removed from module

app/models/module_app.rb

@@ -8,7 +8,7 @@ class ModuleApp
   field :title
   field :sidebar_order,type: Integer,default: 0
 
-  has_and_belongs_to_many :module_tags, dependent: :destroy
+  has_many :module_tags, dependent: :destroy
 
   def refetch_setting!(reg)
     # %w{module_label category base_url version organization author intro update_info create_date}.each  do |field|

app/models/module_tag.rb

@@ -3,20 +3,22 @@ class ModuleTag
   include Mongoid::Timestamps
 
   field :is_default, type: Boolean, default: false
+  field :name, localize: true
 
   has_one :tag, as: :tag_lease, autosave: true
-  has_and_belongs_to_many :module_apps
+  belongs_to :module_app
 
-  after_initialize :init_tag
+  belongs_to :parent, :class_name => 'ModuleTag', :inverse_of => :children
+  has_many :children, :class_name => 'ModuleTag', :inverse_of => :parent, autosave: true, dependent: :destroy
+
+  validates :name, :at_least_one => true
+
+  before_save :init_update_tag
   before_destroy :destroy_tag
 
-  private
+  after_save :update_children
 
-  def init_tag
-    if new_record?
-      self.build_tag(name_translations: self.name_translations, is_default: self.is_default)
-    end
-  end
+  private
 
   def destroy_tag
     Tag.without_callback(:destroy, :before, :destroy_module_tag) do
@@ -24,4 +26,20 @@ class ModuleTag
     end
   end
 
-end
+  def init_update_tag
+    if self.new_record?
+      self.build_tag(name_translations: self.name_translations)
+    else
+      self.tag.name_translations = self.name_translations
+    end
+  end
+
+  def update_children
+    unless self.children.blank?
+      self.children.each do |child|
+        child.update_attributes(name_translations: self.name_translations)
+      end
+    end
+  end
+
+end