Ruby-on-rails ArgumentError：参数数量错误（1 对 2）
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/8813957/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
ArgumentError: wrong number of arguments (1 for 2)
提问by airplaneman19
I'm very new to Rails, MVC, and CRUD, and I'm trying to use the update method to change the amount of votes on a post. I have the following code in my Posts Controller update method:
我对 Rails、MVC 和 CRUD 非常陌生，我正在尝试使用 update 方法来更改帖子的投票数量。我的 Posts Controller 更新方法中有以下代码：
def update
@post = Post.find(params[:id])
if params[:vote] == 'up'
@post.update_column(:ups => @post[:ups] + 1)
elsif params[:vote] == 'down'
@post.update_column(:downs => @post[:downs] + 1)
end
flash[:notice] = "Thanks for voting! This helps us determine important issues in our schools."
redirect_to 'Posts#index'
end
and I have the following code in my routes.rb:
我的routes.rb中有以下代码：
OpenMCJC::Application.routes.draw do
root :to => 'posts#index'
resources :posts
match '/posts/:id/:vote', :to => 'posts#update'
end
After navigating to "/posts/3/up", it throws the following error:
导航到“/posts/3/up”后，它抛出以下错误：
ArgumentError in PostsController#update
wrong number of arguments (1 for 2)
The request parameters according to the page are as such:
根据页面的请求参数如下：
{"id"=>"3",
"vote"=>"up"}
Can you help me figure out what went wrong?
你能帮我弄清楚出了什么问题吗？
回答by Mischa
update_columntakes two arguments. You are only passing one.
update_column需要两个参数。你只是通过了一个。
Instead of:
代替：
@post.update_column(:ups => @post[:ups] + 1)
Try:
尝试：
@post.update_column(:ups, @post[:ups] + 1)
This may seem like twoarguments:
这似乎是两个论点：
:ups => @post[:ups] + 1
but it's actually onehash.
但它实际上是一个哈希值。
With the more commonly used update_attributes, you can pass a hash:
使用更常用的update_attributes，您可以传递散列：
@post.update_attributes(:ups => @post[:ups] + 1)
回答by Peter Brown
As Mischa pointed out, update_columntakes two arguments. However, I would discourage you from using this method. First, it skips validations which may not be what you want. Second, Rails has built-in methods for incrementing or decrementing values. In your case, you could change your controller method to something like this:
正如米沙指出的那样，update_column需要两个论点。但是，我不鼓励您使用这种方法。首先，它会跳过可能不是您想要的验证。其次，Rails 具有用于递增或递减值的内置方法。在您的情况下，您可以将控制器方法更改为如下所示：
if params[:vote] == 'up'
@post.increment(:ups)
elsif params[:vote] == 'down'
@post.increment(:downs)
end
