Ruby on Rails Q & A


What are callbacks in Rails?

In Rails, callbacks are hooks that allow developers to attach custom methods (or “callbacks”) to be triggered during the lifecycle of an object. Specifically, they’re methods that get called at certain moments before or after key changes in the object’s lifecycle, such as before saving to the database, after updating an attribute, or even before an object is destroyed.

These callbacks can be extremely useful for encapsulating related behaviors or for ensuring that certain conditions are met before an object is saved. For instance, they can be used to normalize data before saving it, check the validity of related objects, or automatically timestamp an object when it’s created.

Commonly used callbacks include `before_save`, `after_save`, `before_create`, `after_create`, `before_update`, `after_update`, `before_destroy`, and `after_destroy`. 


Here’s a simple example: imagine a `BlogPost` model where you want to ensure that the title is always title-cased before saving to the database. You could use a `before_save` callback as follows:



class BlogPost < ApplicationRecord

  before_save :titleize_title


  def titleize_title

    self.title = title.titleize





In the above example, every time a `BlogPost` instance is saved, the `titleize_title` method will be triggered, ensuring the title attribute is in title case.

However, while callbacks are powerful, it’s crucial to use them judiciously. Overreliance on callbacks can make models complex and introduce unexpected behaviors, especially if callbacks interact with other parts of the application. It’s often a good practice to keep the callback methods small, single-responsibility, and easy to understand, ensuring that the application remains maintainable and predictable.

Callbacks in Rails are tools in the developer’s arsenal to inject custom behavior during an object’s lifecycle, but, like all tools, they should be used with care and understanding.

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Senior Software Engineer with a focus on remote work. Proficient in Ruby on Rails. Expertise spans y6ears in Ruby on Rails development, contributing to B2C financial solutions and data engineering.