# VariableDuplicatesValidator # # This validator is designed for especially the following condition # - Use `accepts_nested_attributes_for :xxx` in a parent model # - Use `validates :xxx, uniqueness: { scope: :xxx_id }` in a child model class VariableDuplicatesValidator < ActiveModel::EachValidator def validate_each(record, attribute, value) if options[:scope] scoped = value.group_by { |variable| Array(options[:scope]).map { |attr| variable.send(attr) } } scoped.each_value { |scope| validate_duplicates(record, attribute, scope) } else validate_duplicates(record, attribute, value) end end private def validate_duplicates(record, attribute, values) duplicates = values.reject(&:marked_for_destruction?).group_by(&:key).select { |_, v| v.many? }.map(&:first) if duplicates.any? record.errors.add(attribute, "Duplicate variables: #{duplicates.join(", ")}") end end end