Introducing cast_assoc

cast_assoc is a Ruby on Rails gem that provides a simple way to handle nested model attributes when updating records. It allows you to cast records and their associations in a single step, which helps to prevent errors and makes the code easier to read and maintain.

How It Works

When you're updating a record in Rails, you typically handle updating its attributes using Strong Parameters. But what if the record has associations, and those associations have their own attributes that need to be updated too? That's where cast_assoc comes in.

cast_assoc extends the assign_attributes method in Rails, allowing you to cast not only the attributes of the main record, but also any nested associations. It does this by creating a new casted copy of the record and its associations, which validates and assigns the data in a structured way.

To use cast_assoc, you first need to include it in your Gemfile:

gem 'cast_assoc'

Then, in your model, you can define the associations you want to cast using the cast_assoc method:

class BlogPost < ApplicationRecord
  belongs_to :author
  cast_assoc :author
end

class Author < ApplicationRecord
  has_many :blog_posts
end

Now, when you update a BlogPost record, you can use the cast_assoc method to automatically cast its associated Author record:

params = {
  title: 'New Title',
  body: 'New Body',
  author_attributes: {
    name: 'New Name',
    email: 'new@email.com'
  }
}

@blog_post.assign_attributes(params)

The @blog_post record will now be updated with the new title and body, and the author association will be updated with the new name and email. It's that simple!

Conclusion

cast_assoc is a great gem that makes working with nested attributes in Rails much easier. It allows you to easily update a record and its associations in a single step, providing a simple solution to a common problem.