Calling destroy method gives error -undefined method `name' for nil:NilClass - Rails 4

Question

While trying to delete a product, I am getting this error

NoMethodError in ProductsController#destroy
undefined method `name' for nil:NilClass

Controller:

class ProductsController < ApplicationController
 before_action :set_product, only: [:show, :edit, :update, :destroy]

 def destroy
  @product.destroy <-------error highlights on this line
  respond_to do |format|
   format.html { redirect_to some_path }
   format.json { head :no_content }
  end
 end

 private

 def set_product
  @product = Product.find(params[:id])
 end

Model:

class Product < ActiveRecord::Base

 belongs_to :category
 belongs_to :sub_category

 has_one :item , :dependent => :delete
 has_many :carts, :dependent => :delete_all
 has_many :assets , :dependent => :delete_all

end

View:

<%= link_to image_tag('delete.png'), product, method: :delete, data: { confirm: 'Are you sure?' } %>

Upon clicking 'OK' from the pop-up, it throws above described error.@product exists,I have checked.

In development mode, it runs fine, but in Digital Ocean under development mode, it is throwing this error. Please help me to figure it out.

Application trace:

   app/controllers/products_controller.rb:225:in `destroy'

Full trace:

activerecord (4.0.1) lib/active_record/associations/has_many_association.rb:81:in `cached_counter_attribute_name'
activerecord (4.0.1) lib/active_record/associations/has_many_association.rb:104:in `inverse_updates_counter_cache?'
activerecord (4.0.1) lib/active_record/associations/has_many_association.rb:114:in `delete_records'
activerecord (4.0.1) lib/active_record/associations/collection_association.rb:493:in `remove_records'
activerecord (4.0.1) lib/active_record/associations/collection_association.rb:486:in `block in delete_or_destroy'
activerecord (4.0.1) lib/active_record/associations/collection_association.rb:152:in `block in transaction'
activerecord (4.0.1) lib/active_record/connection_adapters/abstract/database_statements.rb:200:in `transaction'
activerecord (4.0.1) lib/active_record/transactions.rb:209:in `transaction'
activerecord (4.0.1) lib/active_record/associations/collection_association.rb:151:in `transaction'
activerecord (4.0.1) lib/active_record/associations/collection_association.rb:486:in `delete_or_destroy'
activerecord (4.0.1) lib/active_record/associations/collection_association.rb:247:in `destroy'
activerecord (4.0.1)  lib/active_record/associations/collection_association.rb:170:in `destroy_all'
activerecord (4.0.1) lib/active_record/associations/has_many_association.rb:26:in `handle_dependency'
 activerecord (4.0.1) lib/active_record/associations/builder/association.rb:97:in `has_many_dependent_for_assets'
 activesupport (4.0.1) lib/active_support/callbacks.rb:397:in `_run__3353912714138952721__destroy__callbacks'
 activesupport (4.0.1) lib/active_support/callbacks.rb:80:in `run_callbacks'
 activerecord (4.0.1) lib/active_record/callbacks.rb:292:in `destroy'
 activerecord (4.0.1) lib/active_record/transactions.rb:265:in `block in destroy'
activerecord (4.0.1) lib/active_record/transactions.rb:326:in `block in with_transaction_returning_status'
activerecord (4.0.1) lib/active_record/connection_adapters/abstract/database_statements.rb:202:in `block in transaction'
activerecord (4.0.1) lib/active_record/connection_adapters/abstract/database_statements.rb:210:in `within_new_transaction'
activerecord (4.0.1) lib/active_record/connection_adapters/abstract/database_statements.rb:202:in `transaction'
activerecord (4.0.1) lib/active_record/transactions.rb:209:in `transaction'
activerecord (4.0.1) lib/active_record/transactions.rb:323:in `with_transaction_returning_status'
activerecord (4.0.1) lib/active_record/transactions.rb:265:in `destroy'
app/controllers/products_controller.rb:225:in `destroy'
    actionpack (4.0.1) lib/action_controller/metal/implicit_render.rb:4:in `send_action'
    actionpack (4.0.1) lib/abstract_controller/base.rb:189:in `process_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:in `block in process_action'
    activesupport (4.0.1) lib/active_support/callbacks.rb:493:in `_run__3348285909198205465__process_action__callbacks'
    activesupport (4.0.1) lib/active_support/callbacks.rb:80:in `run_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:in `block 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:in `process_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:in `process'
 actionpack (4.0.1) lib/abstract_controller/rendering.rb:44:in `process'
actionpack (4.0.1) lib/action_controller/metal.rb:195:in `dispatch'
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:in `dispatch'
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:in `call'
actionpack (4.0.1) lib/action_dispatch/routing/route_set.rb:680:in `call'
rack (1.6.4) lib/rack/deflater.rb:35:in `call'
warden (1.2.3) lib/warden/manager.rb:35:in `block in call'
warden (1.2.3) lib/warden/manager.rb:34:in `catch'
warden (1.2.3) lib/warden/manager.rb:34:in `call'
rack (1.6.4) lib/rack/etag.rb:24:in `call'
rack (1.6.4) lib/rack/conditionalget.rb:38:in `call'
rack (1.6.4) lib/rack/head.rb:13:in `call'
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 (1.6.4) lib/rack/session/abstract/id.rb:225:in `context'
rack (1.6.4) lib/rack/session/abstract/id.rb:220:in `call'
actionpack (4.0.1) lib/action_dispatch/middleware/cookies.rb:486:in `call'
activerecord (4.0.1) lib/active_record/query_cache.rb:36:in `call'
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__753779113942060240__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:in `call'
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:in `call'
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:in `call'
railties (4.0.1) lib/rails/rack/logger.rb:38:in `call_app'
railties (4.0.1) lib/rails/rack/logger.rb:20:in `block 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:in `call'
actionpack (4.0.1) lib/action_dispatch/middleware/request_id.rb:21:in `call'
rack (1.6.4) lib/rack/methodoverride.rb:22:in `call'
rack (1.6.4) lib/rack/runtime.rb:18:in `call'
activesupport (4.0.1) lib/active_support/cache/strategy/local_cache.rb:83:in `call'
rack (1.6.4) lib/rack/lock.rb:17:in `call'
actionpack (4.0.1) lib/action_dispatch/middleware/static.rb:64:in `call'
rack (1.6.4) lib/rack/sendfile.rb:113:in `call'
railties (4.0.1) lib/rails/engine.rb:511:in `call'
railties (4.0.1) lib/rails/application.rb:97:in `call'
rack (1.6.4) lib/rack/tempfile_reaper.rb:15:in `call'
rack (1.6.4) lib/rack/lint.rb:49:in `_call'
rack (1.6.4) lib/rack/lint.rb:37:in `call'
rack (1.6.4) lib/rack/showexceptions.rb:24:in `call'
rack (1.6.4) lib/rack/commonlogger.rb:33:in `call'
rack (1.6.4) lib/rack/chunked.rb:54:in `call'
rack (1.6.4) lib/rack/content_length.rb:15:in `call'
unicorn (5.0.0) lib/unicorn/http_server.rb:562:in `process_client'
unicorn (5.0.0) lib/unicorn/http_server.rb:658:in `worker_loop'
unicorn (5.0.0) lib/unicorn/http_server.rb:508:in `spawn_missing_workers'
unicorn (5.0.0) lib/unicorn/http_server.rb:132:in `start'
unicorn (5.0.0) bin/unicorn:126:in `<top (required)>'
/usr/local/rvm/gems/ruby-2.2.1/bin/unicorn:23:in `load'
/usr/local/rvm/gems/ruby-2.2.1/bin/unicorn:23:in `<main>'
/usr/local/rvm/gems/ruby-2.2.1@global/bin/ruby_executable_hooks:15:in `eval'
/usr/local/rvm/gems/ruby-2.2.1@global/bin/ruby_executable_hooks:15:in `<main>'

item.rb

class Item < ActiveRecord::Base
 belongs_to :user
 belongs_to :order
 belongs_to :product
end

cart.rb

class Cart < ActiveRecord::Base
  belongs_to :user
  belongs_to :product
end

asset.rb

class Asset < ActiveRecord::Base
 mount_uploader :asset1, AssetUploader
 mount_uploader :asset2, AssetUploader
 mount_uploader :asset3, AssetUploader
 mount_uploader :asset4, AssetUploader 
end

If I remove :dependent => :delete_all, then this error is gone, but I need to delete the dependents too.

How to get that done?

Answer 1

Hey the thing is that you re using the dependent destroy option whith a has_many association, which is cant be done. Thid option is available only for a belongs_to association.

Like a User has many posts, and a Post belongs to User. You want to set dependent destroy on Post, cause you re saying : ** I want this association to depend on User in destroy method ** , by cons when deleting a user, all his posts should be deleted with.

I hope i could have halped clearing things for you