Question

我刚刚开始使用rails，每件事情都运转良好，突然间我遇到了错误。

未定义的方法`标题＆＃39;对于＃＆lt;评论：0xbe9aba0＆GT;

我尝试了其他帖子并没有弄清楚出了什么问题。

Extracted source (around line #6):

@article = Article.find(params[:article_id])//line 4
@comment = @article.comments.new(comment_params)//line 5
**@comment.save** //line 6
redirect_to article_path(@article) //line 7

端

堆栈跟踪如下：

＆＃13;

activemodel (4.1.8) lib/active_model/attribute_methods.rb:435:in `method_missing'
activerecord (4.1.8) lib/active_record/attribute_methods.rb:213:in `method_missing'
activemodel (4.1.8) lib/active_model/validator.rb:165:in `block in validate'
activemodel (4.1.8) lib/active_model/validator.rb:164:in `each'
activemodel (4.1.8) lib/active_model/validator.rb:164:in `validate'
activerecord (4.1.8) lib/active_record/validations/presence.rb:5:in `validate'
activesupport (4.1.8) lib/active_support/callbacks.rb:447:in `public_send'
activesupport (4.1.8) lib/active_support/callbacks.rb:447:in `block in make_lambda'
activesupport (4.1.8) lib/active_support/callbacks.rb:184:in `call'
activesupport (4.1.8) lib/active_support/callbacks.rb:184:in `block in simple'
activesupport (4.1.8) lib/active_support/callbacks.rb:86:in `call'
activesupport (4.1.8) lib/active_support/callbacks.rb:86:in `run_callbacks'
activemodel (4.1.8) lib/active_model/validations.rb:376:in `run_validations!'
activemodel (4.1.8) lib/active_model/validations/callbacks.rb:111:in `block in run_validations!'
activesupport (4.1.8) lib/active_support/callbacks.rb:82:in `run_callbacks'
activemodel (4.1.8) lib/active_model/validations/callbacks.rb:111:in `run_validations!'
activemodel (4.1.8) lib/active_model/validations.rb:317:in `valid?'
activerecord (4.1.8) lib/active_record/validations.rb:70:in `valid?'
activerecord (4.1.8) lib/active_record/validations.rb:77:in `perform_validations'
activerecord (4.1.8) lib/active_record/validations.rb:51:in `save'
activerecord (4.1.8) lib/active_record/attribute_methods/dirty.rb:21:in `save'
activerecord (4.1.8) lib/active_record/transactions.rb:268:in `block (2 levels) in save'
activerecord (4.1.8) lib/active_record/transactions.rb:329:in `block in with_transaction_returning_status'
activerecord (4.1.8) lib/active_record/connection_adapters/abstract/database_statements.rb:201:in `block in transaction'
activerecord (4.1.8) lib/active_record/connection_adapters/abstract/database_statements.rb:209:in `within_new_transaction'
activerecord (4.1.8) lib/active_record/connection_adapters/abstract/database_statements.rb:201:in `transaction'
activerecord (4.1.8) lib/active_record/transactions.rb:208:in `transaction'
activerecord (4.1.8) lib/active_record/transactions.rb:326:in `with_transaction_returning_status'
activerecord (4.1.8) lib/active_record/transactions.rb:268:in `block in save'
activerecord (4.1.8) lib/active_record/transactions.rb:283:in `rollback_active_record_state!'
activerecord (4.1.8) lib/active_record/transactions.rb:267:in `save'
app/controllers/comments_controller.rb:6:in `create'
actionpack (4.1.8) lib/action_controller/metal/implicit_render.rb:4:in `send_action'
actionpack (4.1.8) lib/abstract_controller/base.rb:189:in `process_action'
actionpack (4.1.8) lib/action_controller/metal/rendering.rb:10:in `process_action'
actionpack (4.1.8) lib/abstract_controller/callbacks.rb:20:in `block in process_action'
activesupport (4.1.8) lib/active_support/callbacks.rb:113:in `call'
activesupport (4.1.8) lib/active_support/callbacks.rb:113:in `call'
activesupport (4.1.8) lib/active_support/callbacks.rb:229:in `block in halting'
activesupport (4.1.8) lib/active_support/callbacks.rb:229:in `call'
activesupport (4.1.8) lib/active_support/callbacks.rb:229:in `block in halting'
activesupport (4.1.8) lib/active_support/callbacks.rb:166:in `call'
activesupport (4.1.8) lib/active_support/callbacks.rb:166:in `block in halting'
activesupport (4.1.8) lib/active_support/callbacks.rb:166:in `call'
activesupport (4.1.8) lib/active_support/callbacks.rb:166:in `block in halting'
activesupport (4.1.8) lib/active_support/callbacks.rb:166:in `call'
activesupport (4.1.8) lib/active_support/callbacks.rb:166:in `block in halting'
activesupport (4.1.8) lib/active_support/callbacks.rb:86:in `call'
activesupport (4.1.8) lib/active_support/callbacks.rb:86:in `run_callbacks'
actionpack (4.1.8) lib/abstract_controller/callbacks.rb:19:in `process_action'
actionpack (4.1.8) lib/action_controller/metal/rescue.rb:29:in `process_action'
actionpack (4.1.8) lib/action_controller/metal/instrumentation.rb:31:in `block in process_action'
activesupport (4.1.8) lib/active_support/notifications.rb:159:in `block in instrument'
activesupport (4.1.8) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (4.1.8) lib/active_support/notifications.rb:159:in `instrument'
actionpack (4.1.8) lib/action_controller/metal/instrumentation.rb:30:in `process_action'
actionpack (4.1.8) lib/action_controller/metal/params_wrapper.rb:250:in `process_action'
activerecord (4.1.8) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
actionpack (4.1.8) lib/abstract_controller/base.rb:136:in `process'
actionview (4.1.8) lib/action_view/rendering.rb:30:in `process'
actionpack (4.1.8) lib/action_controller/metal.rb:196:in `dispatch'
actionpack (4.1.8) lib/action_controller/metal/rack_delegation.rb:13:in `dispatch'
actionpack (4.1.8) lib/action_controller/metal.rb:232:in `block in action'
actionpack (4.1.8) lib/action_dispatch/routing/route_set.rb:82:in `call'
actionpack (4.1.8) lib/action_dispatch/routing/route_set.rb:82:in `dispatch'
actionpack (4.1.8) lib/action_dispatch/routing/route_set.rb:50:in `call'
actionpack (4.1.8) lib/action_dispatch/journey/router.rb:73:in `block in call'
actionpack (4.1.8) lib/action_dispatch/journey/router.rb:59:in `each'
actionpack (4.1.8) lib/action_dispatch/journey/router.rb:59:in `call'
actionpack (4.1.8) lib/action_dispatch/routing/route_set.rb:678:in `call'
rack (1.5.2) lib/rack/etag.rb:23:in `call'
rack (1.5.2) lib/rack/conditionalget.rb:35:in `call'
rack (1.5.2) lib/rack/head.rb:11:in `call'
actionpack (4.1.8) lib/action_dispatch/middleware/params_parser.rb:27:in `call'
actionpack (4.1.8) 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 (4.1.8) lib/action_dispatch/middleware/cookies.rb:560:in `call'
activerecord (4.1.8) lib/active_record/query_cache.rb:36:in `call'
activerecord (4.1.8) lib/active_record/connection_adapters/abstract/connection_pool.rb:621:in `call'
activerecord (4.1.8) lib/active_record/migration.rb:380:in `call'
actionpack (4.1.8) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
activesupport (4.1.8) lib/active_support/callbacks.rb:82:in `run_callbacks'
actionpack (4.1.8) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (4.1.8) lib/action_dispatch/middleware/reloader.rb:73:in `call'
actionpack (4.1.8) lib/action_dispatch/middleware/remote_ip.rb:76:in `call'
actionpack (4.1.8) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
actionpack (4.1.8) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
railties (4.1.8) lib/rails/rack/logger.rb:38:in `call_app'
railties (4.1.8) lib/rails/rack/logger.rb:20:in `block in call'
activesupport (4.1.8) lib/active_support/tagged_logging.rb:68:in `block in tagged'
activesupport (4.1.8) lib/active_support/tagged_logging.rb:26:in `tagged'
activesupport (4.1.8) lib/active_support/tagged_logging.rb:68:in `tagged'
railties (4.1.8) lib/rails/rack/logger.rb:20:in `call'
actionpack (4.1.8) 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 (4.1.8) lib/active_support/cache/strategy/local_cache_middleware.rb:26:in `call'
rack (1.5.2) lib/rack/lock.rb:17:in `call'
actionpack (4.1.8) lib/action_dispatch/middleware/static.rb:84:in `call'
rack (1.5.2) lib/rack/sendfile.rb:112:in `call'
railties (4.1.8) lib/rails/engine.rb:514:in `call'
railties (4.1.8) 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'
/home/novin/.rvm/rubies/ruby-2.1.3/lib/ruby/2.1.0/webrick/httpserver.rb:138:in `service'
/home/novin/.rvm/rubies/ruby-2.1.3/lib/ruby/2.1.0/webrick/httpserver.rb:94:in `run'
/home/novin/.rvm/rubies/ruby-2.1.3/lib/ruby/2.1.0/webrick/server.rb:295:in `block in start_thread'

＆＃13;

评论类：

＆＃13;

class CommentsController < ApplicationController

  def create
    @article = Article.find(params[:article_id])
    @comment = @article.comments.new(comment_params)
    @comment.save
    redirect_to article_path(@article)
  end

  private

    def comment_params
      params.require(:comment).permit(:name, :msg, :article_id)
    end

end

＆＃13;

文章课

＆＃13;

class ArticlesController < ApplicationController
  def index
    @articles = Article.all
  end

  def show
    @article = Article.find(params[:id])
  end
end

＆＃13;

如果你们需要更多细节，请告诉我们

＆＃13;

class Comment < ActiveRecord::Base
  belongs_to :article
  validates :title, presence: true, length: {minimum: 5}
end

＆＃13;

Answer 1

以下其中一项：

you have a show or index view with a call to name i.e comment.title
you have a validation on name in your comments model

但很难从你提供的信息中分辨出来。你在哪里得到错误？

Answer 2

我怀疑Comment没有名为title的列。试试这个来检查：

$ rails console
> Comment.column_names

并查看数组是否包含"title"

Answer 3

主要问题在于您的Comment型号。第3行validates :title, presence: true, length: {minimum: 5}您的评论表中没有标题栏。

如下方法所示，明确表示您的Comment模型中没有标题栏。

def comment_params
  params.require(:comment).permit(:name, :msg, :article_id)
end

从您的validates :title, presence: true, length: {minimum: 5}模型中删除Comment，一切都会好。

未定义的方法`title＆＃39;对于＃<comment：0xbe9aba0> </comment：0xbe9aba0>

3 个答案: