add revisions

app/models/template.rb

@@ -70,6 +70,7 @@ class Template < ApplicationRecord
   has_many :submissions, dependent: :destroy
   has_many :template_sharings, dependent: :destroy
   has_many :template_accesses, dependent: :destroy
+  has_many :template_versions, dependent: :destroy
   has_many :dynamic_documents, dependent: :destroy
   has_many :dynamic_document_versions, through: :dynamic_documents, source: :versions
 

app/models/template_version.rb

@@ -0,0 +1,44 @@
+# frozen_string_literal: true
+
+# == Schema Information
+#
+# Table name: template_versions
+#
+#  id          :bigint           not null, primary key
+#  data        :text             not null
+#  sha1        :string           not null
+#  created_at  :datetime         not null
+#  updated_at  :datetime         not null
+#  account_id  :bigint           not null
+#  author_id   :bigint           not null
+#  template_id :bigint           not null
+#
+# Indexes
+#
+#  index_template_versions_on_account_id            (account_id)
+#  index_template_versions_on_author_id             (author_id)
+#  index_template_versions_on_template_id_and_sha1  (template_id,sha1) UNIQUE
+#
+# Foreign Keys
+#
+#  fk_rails_...  (account_id => accounts.id)
+#  fk_rails_...  (author_id => users.id)
+#  fk_rails_...  (template_id => templates.id)
+#
+class TemplateVersion < ApplicationRecord
+  belongs_to :template
+  belongs_to :account
+  belongs_to :author, class_name: 'User'
+
+  attribute :data, :string, default: -> { {} }
+
+  serialize :data, coder: JSON
+
+  before_validation :set_account, on: :create
+
+  private
+
+  def set_account
+    self.account ||= template.account
+  end
+end