ruby-on-rails - ActiveRecord::Save 的参数数量错误(0 代表 1)

Question

我在使用 Rails 4 时遇到这个错误:

wrong number of arguments (0 for 1)

在 Controller 中运行这段代码时:

class CommentsController < ApplicationController
  def create
    @comment = @current_user.comments.build(comment_params)
    if @comment.save
      redirect_to :back, flash: { success: "Comment was updated." }
    else
      redirect_to :back, flash: { error: "There was an issue with your comment." }, comment: { content: params[:comment][:content] }
    end
  end

  private

    def comment_params
        params.require(:comment).permit(:post_id, :content)
    end
end

这是模型:

class Comment < ActiveRecord::Base
  belongs_to :post

  belongs_to :user

  validates_presence_of :content

  validates_length_of :attribute, minimum: 20
end

这是堆栈跟踪:

block in ActiveModel::Validations::LengthValidator#validate
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activemodel/lib/active_model/validator.rb, line 151
ActiveModel::Validations::LengthValidator#validate
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activemodel/lib/active_model/validator.rb, line 150
Comment#_callback_before_112
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activesupport/lib/active_support/callbacks.rb, line 281
Comment#_run__664310716__validate__callbacks
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activesupport/lib/active_support/callbacks.rb, line 388
Comment#run_callbacks
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activesupport/lib/active_support/callbacks.rb, line 78
Comment#run_validations!
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activemodel/lib/active_model/validations.rb, line 330
block in Comment#run_validations!
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activemodel/lib/active_model/validations/callbacks.rb, line 106
Comment#_run__664310716__validation__callbacks
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activesupport/lib/active_support/callbacks.rb, line 374
Comment#run_callbacks
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activesupport/lib/active_support/callbacks.rb, line 78
Comment#run_validations!
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activemodel/lib/active_model/validations/callbacks.rb, line 106
Comment#valid?
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activemodel/lib/active_model/validations.rb, line 271
Comment#valid?
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activerecord/lib/active_record/validations.rb, line 70
Comment#perform_validations
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activerecord/lib/active_record/validations.rb, line 78
Comment#save!
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activerecord/lib/active_record/validations.rb, line 57
Comment#save!
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activerecord/lib/active_record/attribute_methods/dirty.rb, line 41
block in Comment#save!
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activerecord/lib/active_record/transactions.rb, line 275
block in Comment#with_transaction_returning_status
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activerecord/lib/active_record/transactions.rb, line 326
block in ActiveRecord::ConnectionAdapters::PostgreSQLAdapter#transaction
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 202
ActiveRecord::ConnectionAdapters::PostgreSQLAdapter#within_new_transaction
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 210
ActiveRecord::ConnectionAdapters::PostgreSQLAdapter#transaction
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 202
Comment.transaction
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activerecord/lib/active_record/transactions.rb, line 209
Comment#with_transaction_returning_status
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activerecord/lib/active_record/transactions.rb, line 323
Comment#save!
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activerecord/lib/active_record/transactions.rb, line 275
CommentsController#create
app/controllers/comments_controller.rb, line 4
CommentsController#send_action
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_controller/metal/implicit_render.rb, line 4
CommentsController#process_action
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/abstract_controller/base.rb, line 189
CommentsController#process_action
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_controller/metal/rendering.rb, line 10
block in CommentsController#process_action
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/abstract_controller/callbacks.rb, line 18
CommentsController#_run__1046107247__process_action__callbacks
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activesupport/lib/active_support/callbacks.rb, line 414
CommentsController#run_callbacks
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activesupport/lib/active_support/callbacks.rb, line 78
CommentsController#process_action
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/abstract_controller/callbacks.rb, line 17
CommentsController#process_action
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_controller/metal/rescue.rb, line 29
block in CommentsController#process_action
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_controller/metal/instrumentation.rb, line 31
block in ActiveSupport::Notifications.instrument
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activesupport/lib/active_support/notifications.rb, line 158
ActiveSupport::Notifications::Instrumenter#instrument
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activesupport/lib/active_support/notifications/instrumenter.rb, line 20
ActiveSupport::Notifications.instrument
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activesupport/lib/active_support/notifications.rb, line 158
CommentsController#process_action
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_controller/metal/instrumentation.rb, line 30
CommentsController#process_action
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_controller/metal/params_wrapper.rb, line 245
CommentsController#process_action
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activerecord/lib/active_record/railties/controller_runtime.rb, line 18
CommentsController#process
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/abstract_controller/base.rb, line 136
CommentsController#process
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/abstract_controller/rendering.rb, line 44
CommentsController#dispatch
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_controller/metal.rb, line 196
CommentsController#dispatch
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_controller/metal/rack_delegation.rb, line 13
block in CommentsController.action
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_controller/metal.rb, line 232
ActionDispatch::Routing::RouteSet::Dispatcher#dispatch
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_dispatch/routing/route_set.rb, line 80
ActionDispatch::Routing::RouteSet::Dispatcher#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_dispatch/routing/route_set.rb, line 48
block in ActionDispatch::Journey::Router#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_dispatch/journey/router.rb, line 69
ActionDispatch::Journey::Router#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_dispatch/journey/router.rb, line 57
ActionDispatch::Routing::RouteSet#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_dispatch/routing/route_set.rb, line 645
ClientSideValidations::Middleware::Validators#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/client_side_validations-6855ba7031d4/lib/client_side_validations/middleware.rb, line 21
Rack::ETag#call
(gem) rack-1.5.2/lib/rack/etag.rb, line 23
Rack::ConditionalGet#call
(gem) rack-1.5.2/lib/rack/conditionalget.rb, line 35
Rack::Head#call
(gem) rack-1.5.2/lib/rack/head.rb, line 11
ActionDispatch::ParamsParser#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_dispatch/middleware/params_parser.rb, line 27
ActionDispatch::Flash#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_dispatch/middleware/flash.rb, line 241
ActionDispatch::Session::EncryptedCookieStore#context
(gem) rack-1.5.2/lib/rack/session/abstract/id.rb, line 225
ActionDispatch::Session::EncryptedCookieStore#call
(gem) rack-1.5.2/lib/rack/session/abstract/id.rb, line 220
ActionDispatch::Cookies#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_dispatch/middleware/cookies.rb, line 452
ActiveRecord::QueryCache#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activerecord/lib/active_record/query_cache.rb, line 36
ActiveRecord::ConnectionAdapters::ConnectionManagement#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb, line 632
ActiveRecord::Migration::CheckPending#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activerecord/lib/active_record/migration.rb, line 366
block in ActionDispatch::Callbacks#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_dispatch/middleware/callbacks.rb, line 29
ActionDispatch::Callbacks#_run__81458556__call__callbacks
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activesupport/lib/active_support/callbacks.rb, line 374
ActionDispatch::Callbacks#run_callbacks
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activesupport/lib/active_support/callbacks.rb, line 78
ActionDispatch::Callbacks#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_dispatch/middleware/callbacks.rb, line 27
ActionDispatch::Reloader#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_dispatch/middleware/reloader.rb, line 64
ActionDispatch::RemoteIp#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_dispatch/middleware/remote_ip.rb, line 76
BetterErrors::Middleware#protected_app_call
(gem) better_errors-0.7.2/lib/better_errors/middleware.rb, line 84
BetterErrors::Middleware#better_errors_call
(gem) better_errors-0.7.2/lib/better_errors/middleware.rb, line 79
BetterErrors::Middleware#call
(gem) better_errors-0.7.2/lib/better_errors/middleware.rb, line 56
ActionDispatch::DebugExceptions#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb, line 17
ActionDispatch::ShowExceptions#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_dispatch/middleware/show_exceptions.rb, line 30
Rails::Rack::Logger#call_app
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/railties/lib/rails/rack/logger.rb, line 38
block in Rails::Rack::Logger#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/railties/lib/rails/rack/logger.rb, line 21
block in ActiveSupport::Logger#tagged
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activesupport/lib/active_support/tagged_logging.rb, line 67
ActiveSupport::Logger::SimpleFormatter#tagged
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activesupport/lib/active_support/tagged_logging.rb, line 25
ActiveSupport::Logger#tagged
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activesupport/lib/active_support/tagged_logging.rb, line 67
Rails::Rack::Logger#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/railties/lib/rails/rack/logger.rb, line 21
ActionDispatch::RequestId#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_dispatch/middleware/request_id.rb, line 21
Rack::MethodOverride#call
(gem) rack-1.5.2/lib/rack/methodoverride.rb, line 21
Rack::Runtime#call
(gem) rack-1.5.2/lib/rack/runtime.rb, line 17
ActiveSupport::Cache::Strategy::LocalCache::Middleware#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/activesupport/lib/active_support/cache/strategy/local_cache.rb, line 72
Rack::Lock#call
(gem) rack-1.5.2/lib/rack/lock.rb, line 17
ActionDispatch::Static#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/actionpack/lib/action_dispatch/middleware/static.rb, line 64
Fourpointohblog::Application#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/railties/lib/rails/engine.rb, line 511
Fourpointohblog::Application#call
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/railties/lib/rails/application.rb, line 96
Rack::ContentLength#call
(gem) rack-1.5.2/lib/rack/content_length.rb, line 14
block in Thin::Connection#pre_process
(gem) thin-1.5.0/lib/thin/connection.rb, line 81
Thin::Connection#pre_process
(gem) thin-1.5.0/lib/thin/connection.rb, line 79
Thin::Connection#process
(gem) thin-1.5.0/lib/thin/connection.rb, line 54
Thin::Connection#receive_data
(gem) thin-1.5.0/lib/thin/connection.rb, line 39
EventMachine.run
(gem) eventmachine-1.0.3/lib/eventmachine.rb, line 187
Thin::Backends::TcpServer#start
(gem) thin-1.5.0/lib/thin/backends/base.rb, line 63
Thin::Server#start
(gem) thin-1.5.0/lib/thin/server.rb, line 159
Rack::Handler::Thin.run
(gem) rack-1.5.2/lib/rack/handler/thin.rb, line 16
Rails::Server#start
(gem) rack-1.5.2/lib/rack/server.rb, line 264
Rails::Server#start
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/railties/lib/rails/commands/server.rb, line 83
block in <top (required)>
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/railties/lib/rails/commands.rb, line 80
<top (required)>
/home/user/.rvm/gems/ruby-1.9.3-p194/bundler/gems/rails-8744632fb564/railties/lib/rails/commands.rb, line 75
<main>
script/rails, line 6
<main>
script/rails, line 0

我试过调用下面的方法，但没有用

• @comment.save!
• @comment.save(@comment)

为什么会导致这个问题。

Answer 1

在 ActiveRecord 模型中不能有名为 attribute 的列，因为 attribute 是 ActiveRecord 中的私有(private)方法: :基类。

将您的列名称更改为其他内容，它将起作用。