nested_association_validations

📦 Validating Nested Associations Automatically

When using accepts_nested_attributes_for, combine it with validates_associated (or rely on autosave: true) to ensure child records are valid before saving the parent.

class Invoice < ApplicationRecord
  has_many :line_items, autosave: true
  accepts_nested_attributes_for :line_items
  validates_associated :line_items
end

class LineItem < ApplicationRecord
  belongs_to :invoice
  validates :amount, numericality: { greater_than: 0 }
end

# Controller
Invoice.create(invoice_params) # fails if any line_item is invalid