LoadError无法自动加载常量 [英] LoadError Unable to autoload constant

问题描述

自动加载器似乎正在加载lib/tools/address而不是我的模型

It seems that autoloader is loading up lib/tools/address and not my model

地址抛出以下错误

LoadError:无法自动加载常量地址，应该是预期的 /lib/tools/address.rb进行定义

LoadError: Unable to autoload constant Address, expected /lib/tools/address.rb to define it

有人可以告诉我我在做什么错.我以为
地址将指向常量模型/address.rb
和
工具::指向lib/tools/address.rb的地址

Can someone tell me what I'm doing wrong. I thought that
Address would point to constant models/address.rb
and
Tools::Address to lib/tools/address.rb

app/models/address.rb

app/models/address.rb

class Address
  blah
end

lib/tools/address.rb

lib/tools/address.rb

module Tools
  class Address
    blah blah
  end
end

推荐答案

以我的经验，使用具有相同名称但具有不同命名空间的多个常量可能很棘手.在您的情况下，您有两个Address常量，一个在顶级，另一个在Tools命名空间内.这可能会使Rails自动加载器感到困惑.

In my experience it can be tricky to use multiple constants with the same name but with different namespaces. In your case you have two Address constants, one at the top level and another inside the Tools namespace. This can confuse the Rails autoloader.

一些可能的解决方案:

当您要使用顶级Address(即您的模型)时，请使用::Address明确引用它.

When you want to use the top-level Address (i.e. your model), refer to it explicitly using ::Address.

如果这不起作用，您还可以使用require_dependency向自动装带器提示您想要的内容.在为您提供LoadError的文件的顶部，放置以下行:

If that doesn't work, you can also use require_dependency to give the autoloader a hint of what you want. At the top of the file that is giving you the LoadError, put this line:

require_dependency("address")

以下是文档:

require_dependency

使用机制解释文件，并将其定义的常量标记为自动加载. file_name可以是字符串，也可以是to_path的响应.

Interprets a file using mechanism and marks its defined constants as autoloaded. file_name can be either a string or respond to to_path.

在绝对需要在此点定义某个常量的代码中使用此方法.一个典型的用例是在不同名称空间中对具有相同相对名称的常量进行确定性的常量名称解析，否则它们的求值将取决于加载顺序.

Use this method in code that absolutely needs a certain constant to be defined at that point. A typical use case is to make constant name resolution deterministic for constants with the same relative name in different namespaces whose evaluation would depend on load order otherwise.

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