如何验证一系列唯一编号？

Question

validates_format_of            :order_of_importance, :on => :create, :with => /^[1-3]{3}$/,
                             :message => "Order of Importance must have 3 Digits"

现在我可以验证使用的数字是1, 2, 3，但我想也确保这些数字不仅被使用，而且每个数字只使用一次。

例如：

应该是有效的数字

2 3 1

1 3 2

1 2 3

不应该是有效的数字：

1 1 2

2 2 1

3 3 3

Answer 1

if subject =~ /\A(?:\A(?=[1-3]{3}\Z)(\d)(?!\1)(\d)(?!(?:\1|\2))\d\Z)\Z/
    # Successful match
else
    # Match attempt failed
end

这将匹配一个在 1-3 范围内恰好有 3 个数字且没有重复数字的字符串。

细分：

"
^              # Assert position at the beginning of the string
(?=            # Assert that the regex below can be matched, starting at this position (positive lookahead)
   [1-3]          # Match a single character in the range between “1” and “3”
      {3}            # Exactly 3 times
   \$              # Assert position at the end of the string (or before the line break at the end of the string, if any)
)
(              # Match the regular expression below and capture its match into backreference number 1
   \\d             # Match a single digit 0..9
)
(?!            # Assert that it is impossible to match the regex below starting at this position (negative lookahead)
   \\1             # Match the same text as most recently matched by capturing group number 1
)
(              # Match the regular expression below and capture its match into backreference number 2
   \\d             # Match a single digit 0..9
)
(?!            # Assert that it is impossible to match the regex below starting at this position (negative lookahead)
   (?:            # Match the regular expression below
                     # Match either the regular expression below (attempting the next alternative only if this one fails)
         \\1             # Match the same text as most recently matched by capturing group number 1
      |              # Or match regular expression number 2 below (the entire group fails if this one fails to match)
         \\2             # Match the same text as most recently matched by capturing group number 2
   )
)
\\d             # Match a single digit 0..9
\$              # Assert position at the end of the string (or before the line break at the end of the string, if any)
"

Answer 2

检查所有 3 项不是更容易吗！有效排列？

编辑：

但是为了迎接挑战： (?:1(?!\d*1)|2(?!\d*2)|3(?!\d*3)){3}

它使用negative lookaheads 来确保号码只被选中一次。

编辑：

Checked with rubular.com.

Answer 3

您可以将字符串分解为 3 个数字。 a、b 和 c。

那么你有很多方法可以检查。例如

min val ==1 and max==3 and sum=6

将 3 放入一个集合中（希望 ruby​​ 有集合类型），集合的大小应该是 3。

等等。

正则表达式可能不是解决这个问题的最佳工具。

Answer 4

正如其他人已经说过的，最好使用方法或其他东西检查唯一性。但是如果你有理由使用正则表达式，那么正则表达式看起来像这样

^(\d)\s*(?!\1)(\d)\s*(?!\1|\2)(\d)$

它在每个数字上使用负前瞻来通过检查已经捕获的组来验证重复。如果你只需要检查 1,2 和 3 那么你可以使用这个

^([123])\s*(?!\1)([123])\s*(?!\1|\2)([123])$

Answer 5

我强烈推荐[在线正则表达式生成器][1]

[1]：http://www.gskinner.com/RegExr/免疑