正则表达式帮助，适用于 rubular 而不是生产环境？可能的 问题？

Question

鉴于此：

Come Find me please. This is paragraph one.\n\nThis is paragraph two. 
Capture everything before me as this is the last sentence.\n\n\n\n
From: XXX XXX <[email protected]>\nDate: Mon, 17 May 2010 10:59:40 -0700\n
To: \"xxx, xxx\" <[email protected]>\nSubject: Re: XXXXXXXX\n\ndone

Lots of other junk here

我想要回来的是：

Come Find me please. This is paragraph one.\n\nThis is paragraph two. 
Capture everything before me as this is the last sentence.

我正在使用以下正则表达式，它在 rubular 上运行良好，但在 Rails 上失败。为什么会出现这种情况？

split(/(From:.*Date.*To:.*Subject:.*?)\n/m).first

Answer 1

根据我的测试，您的代码可以正常工作，只是它后面带有一些

"\n"

。如果您想删除它们，请在开头添加

\n*

。我不知道为什么你有括号，最后一个

?

和

\n

。我把它们脱下来了。

your_string.split(/\n*From:.*Date.*To:.*Subject:.*/m).first

也许使用

sub

更自然。

your_string.sub(/\n*From:.*Date.*To:.*Subject:.*/m, '')

你也可以这样做：

 your_string[/.*?(?=\n*From:.*Date.*To:.*Subject:.*)/m]

Answer 2

如果想提取之前的所有内容，请尝试此解决方案

From:

txt.gsub(/From:.*$/m, '')

/m

选项使

.

匹配换行符。

Answer 3

如果“From:”一词是唯一的，

>> s
=> "Come Find me please. This is paragraph one.\n\nThis is paragraph two. \nCapture everything before me as this is the last sentence.\n\n\n\n\nFrom: XXX XXX <[email protected]>\nDate: Mon, 17 May 2010 10:59:40 -0700\n\nTo: \"xxx, xxx\" <[email protected]>\nSubject: Re: XXXXXXXX\n\ndone"

>> s.split(/From:\s+/).first.strip
=> "Come Find me please. This is paragraph one.\n\nThis is paragraph two. \nCapture everything before me as this is the last sentence."