在帖子控制器，rails 4中，参数错误数量为1​​（0为0）？

I am getting the error message "wrong number of arguments error(1 for 0) in my posts controller in my show action. I will comment the end of that specific line. Thanks for the help.

我在我的显示操作中的帖子控制器中收到错误消息“错误的参数数量错误(1为0)。我将评论该特定行的结尾。感谢您的帮助。

def show
  @post = Post.all(:order => 'created_at DESC') #this is the error line
end

def new
  @post = Post.new
end

def create
  @post = Post.new(params[:post])

  if @post.save
    redirect_to @post
  else
   render :new
  end
end

2 个解决方案

#1

You either have to show 1 post, and it will be:

您要么必须显示1个帖子,它将是:

@post = Post.find(params[:id]) # show

or all posts

或所有帖子

@posts = Post.order('created_at DESC') # index

Taking into account the fact, you write this in show action, you probably meant first.

考虑到这个事实,你在show动作中写这个,你可能首先想的。

---

Also small recommendation regarding strong parameters. Instead of writing this @post = Post.new(params[:post]) you would rather want to write in #create:

关于强参数的小推荐。而不是写这个@post = Post.new(params [:post])你宁愿写#create:

@post = Post.new(post_params) 

private

def post_params
  params.require(:post).permit(:title, :body) #whatsoever your post has
end

#2

You'll want to read the the latest Rails Active Record Query Interface Guide. A lot has changed lately. The short answer is that you now chain together conditions. And .all does not take any arguments -- as the error message is telling you. Instead, you want to use the .order() method:

您需要阅读最新的Rails Active Record Query Interface Guide。最近发生了很多变化。简短的回答是,您现在将条件链接在一起。并且.all不接受任何参数 - 正如错误消息告诉你的那样。相反,您想要使用.order()方法:

@posts = Post.order(created_at: :desc)