accepts_nested_attributes_for is a Rails method that allows you to easily manage the creation, updating, and destruction of associated models through the parent model's attributes. This is particularly useful when you have nested forms or when you want to handle multiple models in a single operation (e.g., creating or updating a User and its associated Profile in one form submission).

class User < ApplicationRecord
  has_one :profile
  accepts_nested_attributes_for :profile
end

Given the User model has a has_one :profile association, and you want to create or update a User and their Profile at the same time, you can use accepts_nested_attributes_for to pass attributes for both models:

user_params = {
  name: "John Doe",
  profile_attributes: { bio: "Developer", age: 30 }
}

user = User.create(user_params)

In this example, Rails will create both a new User and a new Profile with the attributes provided in profile_attributes.
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