# auto_increment [](https://dl.circleci.com/status-badge/redirect/gh/felipediesel/auto_increment/tree/master) [](https://codeclimate.com/github/felipediesel/auto_increment) auto_increment provides automatic incrementation for a integer or string fields in Rails. ## Installation You can use auto_increment as a gem from Rails 4.2 to Rails 6.1. To use the gem version, put the following gem requirement in your `Gemfile`: ```rb gem "auto_increment" ``` ## Usage To work with a auto increment column you used to do something like this in your model: ```rb before_create :set_code def set_code max_code = Operation.maximum(:code) self.code = max_code.to_i + 1 end ``` Looks fine, but not when you need to do it over and over again. In fact auto_increment does it under the cover. All you need to do is this: ```rb auto_increment :code ``` And your code field will be incremented ## Customizing So you have a different column or need a scope. auto_increment provides options. You can use it like this: ```rb auto_increment :letter, scope: [:account_id, :job_id], model_scope: :in_account, initial: 'C', force: true, lock: false, before: :create ``` First argument is the column that will be incremented. Can be integer or string. - scope: you can define columns that will be scoped and you can use as many as you want (default: nil) - model_scope: you can define model scopes that will be executed and you can use as many as you want (default: nil) - initial: initial value of column (default: 1) - force: you can set a value before create and auto_increment will not change that, but if you do want this, set force to true (default: false) - lock: you can set a lock on the max query. (default: false) - before: you can choose a different callback to be used (:create, :save, :validation) (default: create) ## Compatibility Tested with Rails 6.1, 6 in Ruby 2.7.7. Tested with Rails 7.1, 7, 6.1, 6 in Ruby 3.2.2. For older versions, use version 1.5.2. ## License [MIT License](LICENSE.txt)