Active Record CallbacksThis guide teaches you how to hook into the life cycle of your Active Record objects.After reading this guide, you will know: When certain events occur during the life of an Active Record object. How to register, run, and skip callbacks that respond to these events. How to create relational, association, conditional, and transactional callbacks. How to create objects that encapsulate common behavior for your callbacks to be reused.| Ruby on Rails Guides
Active Record MigrationsMigrations are a feature of Active Record that allows you to evolve your database schema over time. Rather than write schema modifications in pure SQL, migrations allow you to use a Ruby Domain Specific Language (DSL) to describe changes to your tables.After reading this guide, you will know: Which generators you can use to create migrations. Which methods Active Record provides to manipulate your database. How to change existing migrations and update your schema. How ...| Ruby on Rails Guides
This guide covers how you can become a part of the ongoing development of Ruby on Rails.After reading this guide, you will know: How to use GitHub to report issues. How to clone main and run the test suite. How to help resolve existing issues. How to contribute to the Ruby on Rails documentation. How to contribute to the Ruby on Rails code. Ruby on Rails is not "someone else's framework". Over the years, thousands of people have contributed to Ruby on Rails ranging from a single character to ...| Ruby on Rails Guides
Active Record Query InterfaceThis guide covers different ways to retrieve data from the database using Active Record.After reading this guide, you will know: How to find records using a variety of methods and conditions. How to specify the order, retrieved attributes, grouping, and other properties of the found records. How to use eager loading to reduce the number of database queries needed for data retrieval. How to use dynamic finder methods. How to use method chaining to use multiple Acti...| Ruby on Rails Guides
Configuring Rails ApplicationsThis guide covers the configuration and initialization features available to Rails applications.After reading this guide, you will know: How to adjust the behavior of your Rails applications. How to add additional code to be run at application start time.| Ruby on Rails Guides
Active Record ValidationsThis guide teaches you how to validate the state of objects before they go into the database using Active Record's validations feature.After reading this guide, you will know: How to use the built-in Active Record validation helpers. How to create your own custom validation methods. How to work with the error messages generated by the validation process.| Ruby on Rails Guides
