add folders structure

app/models/account.rb

@@ -17,7 +17,7 @@ class Account < ApplicationRecord
   has_many :account_configs, dependent: :destroy
   has_many :templates, dependent: :destroy
   has_many :template_folders, dependent: :destroy
-  has_one :default_folder, -> { where(name: TemplateFolder::DEFAULT_NAME) },
+  has_one :default_template_folder, -> { where(name: TemplateFolder::DEFAULT_NAME) },
           class_name: 'TemplateFolder', dependent: :destroy, inverse_of: :account
   has_many :submissions, through: :templates
   has_many :submitters, through: :submissions
@@ -27,9 +27,8 @@ class Account < ApplicationRecord
   attribute :timezone, :string, default: 'UTC'
   attribute :locale, :string, default: 'en-US'
 
-  def default_folder
-    super || template_folders.new(name: TemplateFolder::DEFAULT_NAME,
-                                  author_id: users.minimum(:id))
-                             .tap(&:save!)
+  def default_template_folder
+    super || build_default_template_folder(name: TemplateFolder::DEFAULT_NAME,
+                                           author_id: users.minimum(:id)).tap(&:save!)
   end
 end

app/models/template.rb

@@ -62,6 +62,6 @@ class Template < ApplicationRecord
   private
 
   def maybe_set_default_folder
-    self.folder ||= account.default_folder
+    self.folder ||= account.default_template_folder
   end
 end

app/models/template_folder.rb

@@ -28,7 +28,13 @@ class TemplateFolder < ApplicationRecord
   belongs_to :author, class_name: 'User'
   belongs_to :account
 
-  has_many :templates, dependent: :destroy
+  has_many :templates, dependent: :destroy, foreign_key: :folder_id, inverse_of: :folder
+  has_many :active_templates, -> { where(deleted_at: nil) },
+           class_name: 'Template', dependent: :destroy, foreign_key: :folder_id, inverse_of: :folder
 
   scope :active, -> { where(deleted_at: nil) }
+
+  def default?
+    name == DEFAULT_NAME
+  end
 end