Fix numbers autoincrement

app/models/check.rb

@@ -52,7 +52,9 @@ class Check < ApplicationRecord
                         :standard_text,
                         :powerpoint_text
 
-  after_create { update(number: id) unless number }
+  validates :number, uniqueness: true, presence: true
+
+  before_validation { self.number = self.class.maximum(:id).to_i + 1 unless self.number.present? }
 
   scope(:search, lambda { |term|
     # TODO: Search only fields for current locale.