为什么我得到“未定义的方法”？
我有一个配置文件模型，并且一个用户 has_one 配置文件。
这是我的路线：
resources :users
resources :profiles
这是我的控制器中的显示方法：
def show
@profile = @user.profile
end
为什么当我尝试访问显示视图时会收到此错误：
NoMethodError in ProfilesController#show
undefined method `profile' for nil:NilClass
I have a profile model, and a user has_one profile.
Here's my route:
resources :users
resources :profiles
Here's the show method in my controller:
def show
@profile = @user.profile
end
Why do I get this error when I try to access the show view:
NoMethodError in ProfilesController#show
undefined method `profile' for nil:NilClass
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评论（3）
您需要初始化
@user实例变量。你可能想做这样的事情：无聊的解释：实例变量（前面有
@的变量）默认是nil。它们实际上可以通过为其分配一个非零值来“实例化”。这里，@user是一个实例变量，它指向nil，因为它还没有被分配任何东西。profile在nil的上下文中调用，它没有profile方法，因此您会得到 no method 异常。这与局部变量相反，局部变量以小写字母开头，在这种情况下会引发局部变量未找到异常。You need to initialize the
@userinstance variable. You probably want to do something like this:Boring explanation: Instance variables (the ones with
@in the front) arenilby default. They can be de facto "instantiated" by just assigning a non-nil value to it. Here,@useris an instance variable, and it points to nil because it hasn't been assigned anything.profileis invoked in the context ofnil, which doesn't have aprofilemethod, so you get the no method exception. This is as opposed to local variables, starting with a lower-cased letter, which would in this case have raised a local variable not found exception.因为
@user对象是nil？您在尝试使用 @user 实例变量之前是否填充了它？Because
@userobject isnil? Did you populate@userinstance variable before trying to use it?那是因为 @user 为零，你需要这样的东西
That is because the @user is nil, you need something like this