Error - uninitialized constant Project::Ticket

Question

class TicketsController < ApplicationController
  before_action :set_project
  before_action :set_ticket, only: [:show, :edit, :update, :destroy]



  def show
  end

  def set_ticket
    @ticket = @project.tickets.find(params[:id])
  end

  def set_project
    @project = Project.for(current_user).find(params[:project_id])
    rescue ActiveRecord::RecordNotFound
    flash[:alert] = "The project you were looking " +"for could not be found."
    redirect_to root_path
  end

end

project's template- show.html.erb

<% @project.tickets.each do |ticket| %> 
  <li>
    #<%= ticket.id %> - <%= link_to ticket.title, [@project, ticket] %>
  </li>
<% end %>

I am getting error: uninitialized constant Project::Ticket the first line of show template

This is in my routes file

resources :projects do
  resources :tickets
end

backtrace

'Started GET "/projects/6" for 127.0.0.1 at 2014-03-12 21:47:37 +0530
Processing by ProjectsController#show as HTML
Parameters: {"id"=>"6"}
←[1m←[35mUser Load (0.0ms)←[0m  SELECT "users".* FROM "users" WHERE "users"."i
d" = ? LIMIT 1  [["id", 4]]
←[1m←[36mProject Load (0.0ms)←[0m  ←[1mSELECT "projects".* FROM "projects" WHE
RE "projects"."id" = ? LIMIT 1←[0m  [["id", "6"]]
←[1m←[35mPermission Load (0.0ms)←[0m  SELECT "permissions".* FROM "permissions
" WHERE "permissions"."user_id" = ?  [["user_id", 4]]
Rendered projects/show.html.erb within layouts/application (19.0ms)
Completed 500 Internal Server Error in 27ms

ActionView::Template::Error (uninitialized constant Project::Ticket):
11: <% end %>
12:
13: <ul id='tickets'>
14: <% @project.tickets.each do |ticket| %>
15: <li>
16: #<%= ticket.id %> - <%= link_to ticket.title, [@project, ticket] %>
17: </li>
app/views/projects/show.html.erb:14:in `_app_views_projects_show_html_erb__106
1934704_22827060'


Rendered C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-4.0.1/lib/action_dispa
tch/middleware/templates/rescues/_trace.erb (2.0ms)
Rendered C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-4.0.1/lib/action_dispa
tch/middleware/templates/rescues/_request_and_response.erb (1.0ms)
Rendered C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-4.0.1/lib/action_dispa
tch/middleware/templates/rescues/template_error.erb within rescues/layout (35.0m
s)'

full trace-

activerecord (4.0.1) lib/active_record/inheritance.rb:125:in `compute_type' activerecord (4.0.1)

lib/active_record/reflection.rb:178:in klass' activerecord (4.0.1) lib/active_record/associations/association.rb:123:inklass' activerecord (4.0.1) lib/active_record/associations/collection_association.rb:37:in reader' activerecord (4.0.1) lib/active_record/associations/builder/association.rb:70:intickets' app/views/projects/show.html.erb:14:in _app_views_projects_show_html_erb__1061934704_22827060' actionpack (4.0.1) lib/action_view/template.rb:143:inblock in render' activesupport (4.0.1) lib/active_support/notifications.rb:161:in instrument' actionpack (4.0.1) lib/action_view/template.rb:141:in render' actionpack (4.0.1) lib/action_view/renderer/template_renderer.rb:49:in block (2 levels) in render_template' actionpack (4.0.1) lib/action_view/renderer/abstract_renderer.rb:38:inblock in instrument' activesupport (4.0.1) lib/active_support/notifications.rb:159:in block in instrument' activesupport (4.0.1) lib/active_support/notifications/instrumenter.rb:20:ininstrument' activesupport (4.0.1) lib/active_support/notifications.rb:159:in instrument' actionpack (4.0.1) lib/action_view/renderer/abstract_renderer.rb:38:ininstrument' actionpack (4.0.1) lib/action_view/renderer/template_renderer.rb:48:in block in render_template' actionpack (4.0.1) lib/action_view/renderer/template_renderer.rb:56:in render_with_layout' actionpack (4.0.1) lib/action_view/renderer/template_renderer.rb:47:in render_template' actionpack (4.0.1) lib/action_view/renderer/template_renderer.rb:17:in render' actionpack (4.0.1) lib/action_view/renderer/renderer.rb:42:in render_template' actionpack (4.0.1) lib/action_view/renderer/renderer.rb:23:inrender' actionpack (4.0.1) lib/abstract_controller/rendering.rb:127:in _render_template' actionpack (4.0.1) lib/action_controller/metal/streaming.rb:219:in _render_template' actionpack (4.0.1) lib/abstract_controller/rendering.rb:120:in render_to_body' actionpack (4.0.1) lib/action_controller/metal/rendering.rb:33:in render_to_body' actionpack (4.0.1) lib/action_controller/metal/renderers.rb:26:in render_to_body' actionpack (4.0.1) lib/abstract_controller/rendering.rb:97:inrender' actionpack (4.0.1) lib/action_controller/metal/rendering.rb:16:in render' actionpack (4.0.1) lib/action_controller/metal/instrumentation.rb:41:inblock (2 levels) in render' activesupport (4.0.1) lib/active_support/core_ext/benchmark.rb:12:in block in ms' C:/Ruby193/lib/ruby/1.9.1/benchmark.rb:295:inrealtime' activesupport (4.0.1) lib/active_support/core_ext/benchmark.rb:12:in ms' actionpack (4.0.1) lib/action_controller/metal/instrumentation.rb:41:inblock in render' actionpack (4.0.1) lib/action_controller/metal/instrumentation.rb:84:in cleanup_view_runtime' activerecord (4.0.1) lib/active_record/railties/controller_runtime.rb:25:in cleanup_view_runtime' actionpack (4.0.1) lib/action_controller/metal/instrumentation.rb:40:in render' actionpack (4.0.1) lib/action_controller/metal/implicit_render.rb:10:indefault_render' actionpack (4.0.1) lib/action_controller/metal/implicit_render.rb:5:in send_action' actionpack (4.0.1) lib/abstract_controller/base.rb:189:inprocess_action' actionpack (4.0.1) lib/action_controller/metal/rendering.rb:10:in process_action' actionpack (4.0.1) lib/abstract_controller/callbacks.rb:18:inblock in process_action' activesupport (4.0.1) lib/active_support/callbacks.rb:433:in _run__975686654__process_action__callbacks' activesupport (4.0.1) lib/active_support/callbacks.rb:80:inrun_callbacks' actionpack (4.0.1) lib/abstract_controller/callbacks.rb:17:in process_action' actionpack (4.0.1) lib/action_controller/metal/rescue.rb:29:in process_action' actionpack (4.0.1) lib/action_controller/metal/instrumentation.rb:31:in block in process_action' activesupport (4.0.1) lib/active_support/notifications.rb:159:inblock in instrument' activesupport (4.0.1) lib/active_support/notifications/instrumenter.rb:20:in instrument' activesupport (4.0.1) lib/active_support/notifications.rb:159:in instrument' actionpack (4.0.1) lib/action_controller/metal/instrumentation.rb:30:in process_action' actionpack (4.0.1) lib/action_controller/metal/params_wrapper.rb:245:inprocess_action' activerecord (4.0.1) lib/active_record/railties/controller_runtime.rb:18:in process_action' actionpack (4.0.1) lib/abstract_controller/base.rb:136:inprocess' actionpack (4.0.1) lib/abstract_controller/rendering.rb:44:in process' actionpack (4.0.1) lib/action_controller/metal.rb:195:indispatch' actionpack (4.0.1) lib/action_controller/metal/rack_delegation.rb:13:in dispatch' actionpack (4.0.1) lib/action_controller/metal.rb:231:in block in action' actionpack (4.0.1) lib/action_dispatch/routing/route_set.rb:80:in call' actionpack (4.0.1) lib/action_dispatch/routing/route_set.rb:80:indispatch' actionpack (4.0.1) lib/action_dispatch/routing/route_set.rb:48:in call' actionpack (4.0.1) lib/action_dispatch/journey/router.rb:71:in block in call' actionpack (4.0.1) lib/action_dispatch/journey/router.rb:59:in each' actionpack (4.0.1) lib/action_dispatch/journey/router.rb:59:incall' actionpack (4.0.1) lib/action_dispatch/routing/route_set.rb:680:in call' rack (1.5.2) lib/rack/etag.rb:23:incall' rack (1.5.2) lib/rack/conditionalget.rb:25:in call' rack (1.5.2) lib/rack/head.rb:11:incall' actionpack (4.0.1) lib/action_dispatch/middleware/params_parser.rb:27:in call' actionpack (4.0.1) lib/action_dispatch/middleware/flash.rb:241: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:incall' actionpack (4.0.1) lib/action_dispatch/middleware/cookies.rb:486:in call' activerecord (4.0.1) lib/active_record/query_cache.rb:36:incall' activerecord (4.0.1) lib/active_record/connection_adapters/abstract/connection_pool.rb:626:in call' activerecord (4.0.1) lib/active_record/migration.rb:369:in call' actionpack (4.0.1) lib/action_dispatch/middleware/callbacks.rb:29:in block in call' activesupport (4.0.1) lib/active_support/callbacks.rb:373:in _run__388525736__call__callbacks' activesupport (4.0.1) lib/active_support/callbacks.rb:80:in run_callbacks' actionpack (4.0.1) lib/action_dispatch/middleware/callbacks.rb:27:incall' actionpack (4.0.1) lib/action_dispatch/middleware/reloader.rb:64:in call' actionpack (4.0.1) lib/action_dispatch/middleware/remote_ip.rb:76:incall' actionpack (4.0.1) lib/action_dispatch/middleware/debug_exceptions.rb:17:in call' actionpack (4.0.1) lib/action_dispatch/middleware/show_exceptions.rb:30:incall' railties (4.0.1) lib/rails/rack/logger.rb:38:in call_app' railties (4.0.1) lib/rails/rack/logger.rb:20:inblock in call' activesupport (4.0.1) lib/active_support/tagged_logging.rb:67:in block in tagged' activesupport (4.0.1) lib/active_support/tagged_logging.rb:25:in tagged' activesupport (4.0.1) lib/active_support/tagged_logging.rb:67:in tagged' railties (4.0.1) lib/rails/rack/logger.rb:20:incall' actionpack (4.0.1) lib/action_dispatch/middleware/request_id.rb:21:in call' rack (1.5.2) lib/rack/methodoverride.rb:21:incall' rack (1.5.2) lib/rack/runtime.rb:17:in call' activesupport (4.0.1) lib/active_support/cache/strategy/local_cache.rb:83:incall' rack (1.5.2) lib/rack/lock.rb:17:in call' actionpack (4.0.1) lib/action_dispatch/middleware/static.rb:64:incall' rack (1.5.2) lib/rack/sendfile.rb:112:in call' railties (4.0.1) lib/rails/engine.rb:511:incall' railties (4.0.1) lib/rails/application.rb:97:in call' rack (1.5.2) lib/rack/lock.rb:17:incall' rack (1.5.2) lib/rack/content_length.rb:14:in call' rack (1.5.2) lib/rack/handler/webrick.rb:60:inservice' C:/Ruby193/lib/ruby/1.9.1/webrick/httpserver.rb:138:in service' C:/Ruby193/lib/ruby/1.9.1/webrick/httpserver.rb:94:inrun' C:/Ruby193/lib/ruby/1.9.1/webrick/server.rb:191:in `block in start_thread'

 class Project < ActiveRecord::Base

 has_many :tickets, dependent: :destroy

has_many :permissions, as: :thing
scope :viewable_by, ->(user) do
    joins(:permissions).where(permissions: { action: "view",
        user_id: user.id })
end

  scope :for, ->(user) do
    user.admin? ? Project.all : Project.viewable_by(user)
  end
  validates :name, presence: true

 end

Answer 1

There is some model which Rails is not able to pluralize/singularize correctly in your case. Thus, it is not able to fetch the class name from associations.

Specify the associations along with classnames.

has_many :tickets, class_name: Ticket, dependent: :destroy

Do similar on the other side belongs_to of the association.

As suggested in another answer, you must have a Ticket model. If this is correctly present, then you should not have to set class_name in this case.