Can't use a model method in views - ruby-on-rails

Question

I'm creating a ticket booking app as my sample project using Ruby on Rails 4.1. Three are three models - Events, Tickets and Bookings. Events have many tickets and bookings. Tickets have many bookings and they belong to events. Bookings belongs to events and tickets.
The tickets controller looks like:
class TicketsController < ApplicationController
def index
#event = Event.find(params[:event_id])
#tickets = #event.tickets.all
end
def show
#event = Event.find(params[:event_id])
#ticket = #event.tickets.find(params[:id])
end
def new
#event = Event.find(params[:event_id])
#ticket = Ticket.new
end
def create
#event = Event.find(params[:event_id])
#ticket = #event.tickets.create(ticket_params)
if #ticket.save
redirect_to [#event, #ticket]
else
render 'new'
end
end
def edit
#event = Event.find(params[:event_id])
#ticket= #event.tickets.find(params[:id])
end
def update
#event = Event.find(params[:event_id])
#ticket = #event.tickets.find(params[:id])
if #ticket.update(ticket_params)
redirect_to [#event, #ticket]
else
render 'edit'
end
end
def destroy
#event = Event.find(params[:event_id])
#ticket = #event.tickets.find(params[:id])
#ticket.destroy
redirect_to event_tickets_path
end
private
def ticket_params
params.require(:ticket).permit(:ticket_name, :booking_start_date, :booking_end_date, :ticket_price, :ticket_quantity, :minimum_quantity, :maximum_quantity, :terms_conditions, :more_information)
end
end
The ticket model looks like this
class Ticket < ActiveRecord::Base
belongs_to :event
has_many :bookings
def maximum_tickets_allowed
max = ticket.maximum_quantity.to_i
self.maximum_quantity = (1..max).to_a
end
end
The Tickets show file looks like:
<h2>Tickets</h2>
<p><%= #ticket.ticket_name %></p>
<p><%= #ticket.booking_start_date %></p>
<p><%= #ticket.booking_end_date %></p>
<p><%= #ticket.maximum_tickets_allowed %></p>
maxium_quantity is the maximum number of tickets a person can book and I'm trying here to convert it to an array to be used in collection_select.
Now, if I use <%= #ticket.maximum_tickets_allowed %> I get the undefined methodmaximum_tickets_allowed'error. I tried usingself.maximum_tickets_allowed` but it doesn't work. Where am I going wrong?
Full Stack Trace of the error:
activemodel (4.1.1) lib/active_model/attribute_methods.rb:435:in `method_missing'
activerecord (4.1.1) lib/active_record/attribute_methods.rb:206:in `method_missing'
app/views/tickets/show.html.erb:6:in `_app_views_tickets_show_html_erb__2112154808966627486_70166705061960'
actionview (4.1.1) lib/action_view/template.rb:145:in `block in render'
activesupport (4.1.1) lib/active_support/notifications.rb:161:in `instrument'
actionview (4.1.1) lib/action_view/template.rb:339:in `instrument'
actionview (4.1.1) lib/action_view/template.rb:143:in `render'
actionview (4.1.1) lib/action_view/renderer/template_renderer.rb:55:in `block (2 levels) in render_template'
actionview (4.1.1) lib/action_view/renderer/abstract_renderer.rb:38:in `block in instrument'
activesupport (4.1.1) lib/active_support/notifications.rb:159:in `block in instrument'
activesupport (4.1.1) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (4.1.1) lib/active_support/notifications.rb:159:in `instrument'
actionview (4.1.1) lib/action_view/renderer/abstract_renderer.rb:38:in `instrument'
actionview (4.1.1) lib/action_view/renderer/template_renderer.rb:54:in `block in render_template'
actionview (4.1.1) lib/action_view/renderer/template_renderer.rb:62:in `render_with_layout'
actionview (4.1.1) lib/action_view/renderer/template_renderer.rb:53:in `render_template'
actionview (4.1.1) lib/action_view/renderer/template_renderer.rb:17:in `render'
actionview (4.1.1) lib/action_view/renderer/renderer.rb:42:in `render_template'
actionview (4.1.1) lib/action_view/renderer/renderer.rb:23:in `render'
actionview (4.1.1) lib/action_view/rendering.rb:99:in `_render_template'
actionpack (4.1.1) lib/action_controller/metal/streaming.rb:217:in `_render_template'
actionview (4.1.1) lib/action_view/rendering.rb:82:in `render_to_body'
actionpack (4.1.1) lib/action_controller/metal/rendering.rb:32:in `render_to_body'
actionpack (4.1.1) lib/action_controller/metal/renderers.rb:32:in `render_to_body'
actionpack (4.1.1) lib/abstract_controller/rendering.rb:25:in `render'
actionpack (4.1.1) lib/action_controller/metal/rendering.rb:16:in `render'
actionpack (4.1.1) lib/action_controller/metal/instrumentation.rb:41:in `block (2 levels) in render'
activesupport (4.1.1) lib/active_support/core_ext/benchmark.rb:12:in `block in ms'
/Users/mohan/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/benchmark.rb:294:in `realtime'
activesupport (4.1.1) lib/active_support/core_ext/benchmark.rb:12:in `ms'
actionpack (4.1.1) lib/action_controller/metal/instrumentation.rb:41:in `block in render'
actionpack (4.1.1) lib/action_controller/metal/instrumentation.rb:84:in `cleanup_view_runtime'
activerecord (4.1.1) lib/active_record/railties/controller_runtime.rb:25:in `cleanup_view_runtime'
actionpack (4.1.1) lib/action_controller/metal/instrumentation.rb:40:in `render'
actionpack (4.1.1) lib/action_controller/metal/implicit_render.rb:10:in `default_render'
actionpack (4.1.1) lib/action_controller/metal/implicit_render.rb:5:in `send_action'
actionpack (4.1.1) lib/abstract_controller/base.rb:189:in `process_action'
actionpack (4.1.1) lib/action_controller/metal/rendering.rb:10:in `process_action'
actionpack (4.1.1) lib/abstract_controller/callbacks.rb:20:in `block in process_action'
activesupport (4.1.1) lib/active_support/callbacks.rb:113:in `call'
activesupport (4.1.1) lib/active_support/callbacks.rb:113:in `call'
activesupport (4.1.1) lib/active_support/callbacks.rb:229:in `block in halting'
activesupport (4.1.1) lib/active_support/callbacks.rb:229:in `call'
activesupport (4.1.1) lib/active_support/callbacks.rb:229:in `block in halting'
activesupport (4.1.1) lib/active_support/callbacks.rb:166:in `call'
activesupport (4.1.1) lib/active_support/callbacks.rb:166:in `block in halting'
activesupport (4.1.1) lib/active_support/callbacks.rb:166:in `call'
activesupport (4.1.1) lib/active_support/callbacks.rb:166:in `block in halting'
activesupport (4.1.1) lib/active_support/callbacks.rb:166:in `call'
activesupport (4.1.1) lib/active_support/callbacks.rb:166:in `block in halting'
activesupport (4.1.1) lib/active_support/callbacks.rb:86:in `call'
activesupport (4.1.1) lib/active_support/callbacks.rb:86:in `run_callbacks'
actionpack (4.1.1) lib/abstract_controller/callbacks.rb:19:in `process_action'
actionpack (4.1.1) lib/action_controller/metal/rescue.rb:29:in `process_action'
actionpack (4.1.1) lib/action_controller/metal/instrumentation.rb:31:in `block in process_action'
activesupport (4.1.1) lib/active_support/notifications.rb:159:in `block in instrument'
activesupport (4.1.1) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (4.1.1) lib/active_support/notifications.rb:159:in `instrument'
actionpack (4.1.1) lib/action_controller/metal/instrumentation.rb:30:in `process_action'
actionpack (4.1.1) lib/action_controller/metal/params_wrapper.rb:250:in `process_action'
activerecord (4.1.1) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
actionpack (4.1.1) lib/abstract_controller/base.rb:136:in `process'
actionview (4.1.1) lib/action_view/rendering.rb:30:in `process'
actionpack (4.1.1) lib/action_controller/metal.rb:195:in `dispatch'
actionpack (4.1.1) lib/action_controller/metal/rack_delegation.rb:13:in `dispatch'
actionpack (4.1.1) lib/action_controller/metal.rb:231:in `block in action'
actionpack (4.1.1) lib/action_dispatch/routing/route_set.rb:80:in `call'
actionpack (4.1.1) lib/action_dispatch/routing/route_set.rb:80:in `dispatch'
actionpack (4.1.1) lib/action_dispatch/routing/route_set.rb:48:in `call'
actionpack (4.1.1) lib/action_dispatch/journey/router.rb:71:in `block in call'
actionpack (4.1.1) lib/action_dispatch/journey/router.rb:59:in `each'
actionpack (4.1.1) lib/action_dispatch/journey/router.rb:59:in `call'
actionpack (4.1.1) lib/action_dispatch/routing/route_set.rb:676:in `call'
rack (1.5.2) lib/rack/etag.rb:23:in `call'
rack (1.5.2) lib/rack/conditionalget.rb:25:in `call'
rack (1.5.2) lib/rack/head.rb:11:in `call'
actionpack (4.1.1) lib/action_dispatch/middleware/params_parser.rb:27:in `call'
actionpack (4.1.1) lib/action_dispatch/middleware/flash.rb:254:in `call'
rack (1.5.2) lib/rack/session/abstract/id.rb:225:in `context'
rack (1.5.2) lib/rack/session/abstract/id.rb:220:in `call'
actionpack (4.1.1) lib/action_dispatch/middleware/cookies.rb:560:in `call'
activerecord (4.1.1) lib/active_record/query_cache.rb:36:in `call'
activerecord (4.1.1) lib/active_record/connection_adapters/abstract/connection_pool.rb:621:in `call'
activerecord (4.1.1) lib/active_record/migration.rb:380:in `call'
actionpack (4.1.1) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
activesupport (4.1.1) lib/active_support/callbacks.rb:82:in `run_callbacks'
actionpack (4.1.1) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (4.1.1) lib/action_dispatch/middleware/reloader.rb:73:in `call'
actionpack (4.1.1) lib/action_dispatch/middleware/remote_ip.rb:76:in `call'
actionpack (4.1.1) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
actionpack (4.1.1) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
railties (4.1.1) lib/rails/rack/logger.rb:38:in `call_app'
railties (4.1.1) lib/rails/rack/logger.rb:20:in `block in call'
activesupport (4.1.1) lib/active_support/tagged_logging.rb:68:in `block in tagged'
activesupport (4.1.1) lib/active_support/tagged_logging.rb:26:in `tagged'
activesupport (4.1.1) lib/active_support/tagged_logging.rb:68:in `tagged'
railties (4.1.1) lib/rails/rack/logger.rb:20:in `call'
actionpack (4.1.1) lib/action_dispatch/middleware/request_id.rb:21:in `call'
rack (1.5.2) lib/rack/methodoverride.rb:21:in `call'
rack (1.5.2) lib/rack/runtime.rb:17:in `call'
activesupport (4.1.1) lib/active_support/cache/strategy/local_cache_middleware.rb:26:in `call'
rack (1.5.2) lib/rack/lock.rb:17:in `call'
actionpack (4.1.1) lib/action_dispatch/middleware/static.rb:64:in `call'
rack (1.5.2) lib/rack/sendfile.rb:112:in `call'
railties (4.1.1) lib/rails/engine.rb:514:in `call'
railties (4.1.1) lib/rails/application.rb:144:in `call'
rack (1.5.2) lib/rack/lock.rb:17:in `call'
rack (1.5.2) lib/rack/content_length.rb:14:in `call'
rack (1.5.2) lib/rack/handler/webrick.rb:60:in `service'
/Users/mohan/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/webrick/httpserver.rb:138:in `service'
/Users/mohan/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/webrick/httpserver.rb:94:in `run'
/Users/mohan/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/webrick/server.rb:295:in `block in start_thread'

Answer 1

You're invoking ticket.maximum_quanitity inside the method, should it not just be maximum_quantity since you're using a ticket instance method?

Answer 2

Some things to think about.
From the comments, it sounds like maybe the #ticket variable is nil? I'm not sure if #event.tickets.find(params[:id]) will throw an ActiveRecord::RecordNotFoundError like Ticket.find will. The way you get data for your controllers is kind of butting heads with the Rails way. There is a one to many relationship between Ticket and Event. There is no need to pass an event_id and id to the TicketsController#show method. Just pass the ticket Id:
class TicketsController < ApplicationController
def show
#ticket = Ticket.find params[:id]
#event = #ticket.event
end
end
Using Ticket.find will raise an ActiveRecord::RecordNotFoundError if the ticket doesn't exist. If I remember correctly, the default controller error handling in Rails should trap that specific exception and render a 404 Not Found page, so after Ticket.find you are assured to have a Ticket object.
Next, if you still need an #event instance variable, use the ActiveRecord relations to get it via #ticket.event.
Now the model itself would need the following code:
class Ticket < ActiveRecord::Base
belongs_to :event
has_many :bookings
def maximum_tickets_allowed
(1..self.maximum_quantity).to_a
end
end
The maximum_tickets_allowed method should just return an array. I'm also wondering if the method call as the end value of the Range is tripping up the Ruby interpreter. You could try instantiating a Range object directly:
def maximum_tickets_allowed
Range.new(1, maximum_quantity).to_a
end
The view remains unchanged:
<h2>Tickets</h2>
<p><%= #ticket.ticket_name %></p>
<p><%= #ticket.booking_start_date %></p>
<p><%= #ticket.booking_end_date %></p>
<p><%= #ticket.maximum_tickets_allowed %></p>
Edit #1: As the comments above mention, make sure you've run all the Active Record migrations in case the maximum_quantity column in the database has been added recently, otherwise that method will not be auto generated by ActiveRecord when the Rails app boots up.
Edit #2: In your show method, you are finding the Event, then all tickets and grabbing only one of the tickets available to the event. That's not as efficient as grabbing the ticket, since you've got the id, and then grabbing the event from the ticket object.
I didn't find any documentation on the find method of an ActiveRecord collection, so I'm not able to validate its behavior.