如何从连接到控制器的过滤器中渲染字符串的一部分
我有一些代码需要在 Rails 1.0 应用程序的多个控制器中使用（出于奇怪的原因，我不能升级到较新的 Rails）。我已将相关代码提取到文件管理器对象中，并使用 around_filter 构造来执行它。
在提取之前，我使用 render_to_string() 方法将渲染的部分的内容获取到字符串中。但是，此方法受到保护，因此我无法从 Filter 对象内访问它。作为解决方法，我尝试将其添加到我的 ApplicationController 中：
def render_to_string(*a)
super(*a)
end
这似乎解决了保护级别问题，但现在我收到错误：
Can only render or redirect once per action
当提取之前没有发生此类错误时。为什么？我应该在这里采取不同的方法吗？
I have some code I need to use in multiple controllers in a rails 1.0 application (I can't, for strange reasons upgrade to a newer rails). I've extracted the relevant code into a filer object, and I'm using the around_filter construct to execute it.
Before the extract, I was using the method render_to_string() to get the contents of a rendered partial into a string. However, this method is protected, so I am unable to access it from within my Filter object. As a workaround, I tried adding this to my ApplicationController:
def render_to_string(*a)
super(*a)
end
this seems to have remedied the protection level issue, but now I get the error:
Can only render or redirect once per action
When no such error occurred before the extraction. Why? Is there a different approach I should take here?
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据我所知，动作将在执行任何过滤器之前调用渲染。由于 render_to_string 通过运行渲染来工作，将结果保存到字符串并实质上撤消渲染，因此会出现“每个操作只能渲染或重定向一次”，因为对渲染的临时调用是在“真正”的渲染调用之后进行的。
我通过在操作结束时简单地调用 after 方法而不是使用 after_filter 或 around_filter 来修复此问题。
我最终还将过滤器移至混合中，以更优雅地避免保护级别问题。
As far as I can tell , an action will call render prior to executing any filters. Since render_to_string works by running render, saving the result to a string and essentially undoing the render, the "Can only render or redirect once per action" comes up because the temporary call to render comes after the "real" call to render.
I fixed this, by simply calling my after method at the end of my action rather than using after_filter or around_filter.
I also ended up moving my filters into a Mix-in, to more elegantly avoid the protection level issue.