ActiveRecord::ReadOnlyRecord Exception raised when parent is readonly - ruby-on-rails

Question

I have the following two models:
# app/models/customer.rb
class Customer < ActiveRecord::Base
has_paper_trail
serialize :mail_opt_out, Set
before_create :generate_token
has_many :wallets
has_many :tickets, through: :wallets
...
# We have a special seeded customer with id -1 that we don't want changing
def readonly?
persisted? && id < 0
end
end
# app/models/ticket.rb
class Ticket < ActiveRecord::Base
include SparkCast
has_paper_trail
belongs_to :price
belongs_to :basket
belongs_to :occurrence
has_one :event, through: :occurrence
has_one :wallet, through: :basket
has_one :basket_type, through: :basket
has_one :customer, through: :basket
delegate :id, to: :customer, allow_nil: true
...
def admit
ensure_can_admit
self.state = 'admitted'
self.save!
end
cast_on :admit, room: :admittance
def as_cast
{
id: id,
customer_id: customer_id
}
end
end
The relevant association is a little convoluted, but is customers -> wallets -> baskets -> tickets.
When I call admit on an instance of a ticket that belongs to our customer with id -1, (which is read only) I get an ActiveRecord::ReadOnlyRecord exception.
I'm confused as to what is causing this, as neither ticket nor customer have any before_update callbacks. If I change
has_one :customer, through: :basket
to
delegate :customer, to: :basket
then everything is fine. Something seems to be either trying to update the customer, or at least checking if it is readonly.
I've done a bit of stepping through the save procedure using byebug, but haven't been able to find anything useful.
What is likely to be checking if an associated model is readonly, and how do I get around this? Is using delegate the best option here?
Edited to add:
Also including SparkCast, which I had omitted previously. Removing the cast_on method from my ticket model is fixing the problem.
# app/models/concerns/spark_cast.rb
module SparkCast
extend ActiveSupport::Concern
module ClassMethods
def cast_on(*args)
# Options are the last argument.
options = args.pop
room = options[:room]
args.each do |operation|
class_eval do
begin
alias_method "#{operation}_without_cast", operation
define_method operation do |*args|
cast_hash = as_cast
...
send("#{operation}_without_cast", *args)
cast(room, operation, cast_hash)
end
rescue NameError => e
raise "#{e.name} has not been defined yet. Include cast_on after method definition"
end
end
end
end
end
end
Backtrace:
- activerecord (4.1.0) lib/active_record/persistence.rb:481:in `create_or_update'
- activerecord (4.1.0) lib/active_record/callbacks.rb:302:in `block in create_or_update'
- activesupport (4.1.0) lib/active_support/callbacks.rb:113:in `call'
- activesupport (4.1.0) lib/active_support/callbacks.rb:166:in `block in halting'
- activesupport (4.1.0) lib/active_support/callbacks.rb:86:in `run_callbacks'
- activerecord (4.1.0) lib/active_record/callbacks.rb:302:in `create_or_update'
- activerecord (4.1.0) lib/active_record/persistence.rb:103:in `save'
- activerecord (4.1.0) lib/active_record/validations.rb:51:in `save'
- activerecord (4.1.0) lib/active_record/attribute_methods/dirty.rb:21:in `save'
- activerecord (4.1.0) lib/active_record/transactions.rb:268:in `block (2 levels) in save'
- activerecord (4.1.0) lib/active_record/transactions.rb:329:in `block in with_transaction_returning_status'
- activerecord (4.1.0) lib/active_record/connection_adapters/abstract/database_statements.rb:209:in `transaction'
- activerecord (4.1.0) lib/active_record/transactions.rb:208:in `transaction'
- activerecord (4.1.0) lib/active_record/transactions.rb:326:in `with_transaction_returning_status'
- activerecord (4.1.0) lib/active_record/transactions.rb:268:in `block in save'
- activerecord (4.1.0) lib/active_record/transactions.rb:283:in `rollback_active_record_state!'
- activerecord (4.1.0) lib/active_record/transactions.rb:267:in `save'
- activerecord (4.1.0) lib/active_record/autosave_association.rb:393:in `save_has_one_association'
- activerecord (4.1.0) lib/active_record/autosave_association.rb:188:in `block in add_autosave_association_callbacks'
- activesupport (4.1.0) lib/active_support/callbacks.rb:424:in `block in make_lambda'
- activesupport (4.1.0) lib/active_support/callbacks.rb:221:in `block in halting_and_conditional'
- activesupport (4.1.0) lib/active_support/callbacks.rb:86:in `run_callbacks'
- activerecord (4.1.0) lib/active_record/callbacks.rb:310:in `update_record'
- activerecord (4.1.0) lib/active_record/timestamp.rb:70:in `update_record'
- activerecord (4.1.0) lib/active_record/persistence.rb:482:in `create_or_update'
- activerecord (4.1.0) lib/active_record/callbacks.rb:302:in `block in create_or_update'
- activesupport (4.1.0) lib/active_support/callbacks.rb:113:in `call'
- activesupport (4.1.0) lib/active_support/callbacks.rb:166:in `block in halting'
- activesupport (4.1.0) lib/active_support/callbacks.rb:166:in `block in halting'
- activesupport (4.1.0) lib/active_support/callbacks.rb:166:in `block in halting'
- activesupport (4.1.0) lib/active_support/callbacks.rb:166:in `block in halting'
- activesupport (4.1.0) lib/active_support/callbacks.rb:166:in `block in halting'
- activesupport (4.1.0) lib/active_support/callbacks.rb:86:in `run_callbacks'
- activerecord (4.1.0) lib/active_record/callbacks.rb:302:in `create_or_update'
- activerecord (4.1.0) lib/active_record/persistence.rb:125:in `save!'
- activerecord (4.1.0) lib/active_record/validations.rb:57:in `save!'
- activerecord (4.1.0) lib/active_record/attribute_methods/dirty.rb:29:in `save!'
- activerecord (4.1.0) lib/active_record/transactions.rb:273:in `block in save!'
- activerecord (4.1.0) lib/active_record/transactions.rb:329:in `block in with_transaction_returning_status'
- activerecord (4.1.0) lib/active_record/connection_adapters/abstract/database_statements.rb:211:in `block in transaction'
- activerecord (4.1.0) lib/active_record/connection_adapters/abstract/database_statements.rb:219:in `within_new_transaction'
- activerecord (4.1.0) lib/active_record/connection_adapters/abstract/database_statements.rb:211:in `transaction'
- activerecord (4.1.0) lib/active_record/transactions.rb:208:in `transaction'
- activerecord (4.1.0) lib/active_record/transactions.rb:326:in `with_transaction_returning_status'
- activerecord (4.1.0) lib/active_record/transactions.rb:273:in `save!'
- () home/hayden/development/SparkSeat/api/app/models/ticket.rb:79:in `admit'