Question

面对这个问题，我有我的看法

 <%= form_for(:pin, :url => {:action =>"fees"}) do |f| %>
 <%= f.text_field :pin_no %>
 <%= f.submit "Check Pin" , :class => "new_button round" %>
 <% end %>

在我的控制器中我有

def fees
@title = "Pay Fees"
pin = Pin.check_pin(params[:pin][:pin_no])
if pin.nil?
  flash.now[:error] = "Pin is not Avaliable"
  render 'fees'
else
  flash.now[:success] = "Pin Avaliable"
end
end

在我的模型中，我有一个如此定义的check_pin方法

def check_pin(pin_to_check)  
  pin = find_by_pin_no(pin_to_check)
   if pin.nil?
     nil
   else
     pin
    end
  end

我总是有这个错误

You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.[]

我在这里想念的是什么？

Answer 1

只有在您发布表单时才会收到params[:pin][:pin_no]，因此错误为nil.[]，因此只有在表单发布时才添加request.post?进行检查

def fees
  @title = "Pay Fees"
  if request.post?
    pin = Pin.check_pin(params[:pin][:pin_no])
    if pin.nil?
      flash.now[:error] = "Pin is not Avaliable"
      render 'fees'
    else
      flash.now[:success] = "Pin Avaliable"
    end
  end
end

Answer 2

如果您尝试简化它并废弃检查引脚方法并执行此操作，那该怎么办：

def fees
  @title = "Pay Fees"
  if p = Pin.find_by_pin_no params[:pin][:pin_no]
    flash.now[:success] = "Pin: #{p} is Avaliable"
  else
    flash.now[:error] = "Pin is not Avaliable"
    render 'fees'
  end
end

RoR：你有一个你没想到的零对象

2 个答案: