ruby-on-rails - Rails 验证 NOT 在正则表达式中

Question

我正在尝试创建一个 Rails 3 验证，以确保人们没有使用常见的免费电子邮件地址之一。

我的想法是这样的....

validates_format_of :email, :with => /^((?!gmail).*)$|^((?!yahoo).*)$|^((?!hotmail).*)$/

或

validates_exclusion_of :email, :in => %w( gmail. GMAIL. hotmail. HOTMAIL. live. LIVE. aol. AOL. ), :message => "You must use your corporate email address."

但两者都不能正常工作。有什么想法吗？

Answer 1

基本上，您已经编写了一个匹配任何内容的正则表达式。让我们分解一下。

/
  ^(            # [ beginning of string
    (?!gmail)   #   followed by anything other than "gmail"
    .           #   followed by any one character
  )$            #   followed by the end the of string
  |             # ] OR [
  ^(            #   beginning of the string
    (?!yahoo)   #   followed by anything other than "yahoo"
    .           #   followed by any one character
  )$            #   followed by the end of the string
  |             # ] OR [
  ^(            #   beginning of the string
    (?!hotmail) #   followed by anything other than "hotmail"
    .*          #   followed by any or no characters 
  )$            #   followed by the end the of string
/               # ]

仔细想想，您会发现唯一不匹配的字符串是以“gmail”、“yahoo”、和“hotmail”开头的字符串——全部在同时，这是不可能的。

你真正想要的是这样的:

/
  .+@                      # one or more characters followed by @
  (?!                      # followed by anything other than...
    (gmail|yahoo|hotmail)  # [ one of these strings
    \.                     #   followed by a literal dot
  )                        # ]
  .+                       # followed by one or more characters
  $                        # and the end of the string
/i                         # case insensitive

把它放在一起，你有:

expr = /.+@(?!(gmail|yahoo|hotmail)\.).+$/i

test_cases = %w[ foo@gmail.com
                 bar@yahoo.com
                 BAZ@HOTMAIL.COM
                 qux@example.com
                 quux
               ]

test_cases.map {|addr| expr =~ addr }
# => [nil, nil, nil, 0, nil]
#    (nil means no match, 0 means there was a match starting at character 0)