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Ruby | We cope with NoMethodError when it does not match in regular ex

2019/04/16に公開

problem

When using capture with regular expressions. You can back reference the matched value by hash.

 'Welcome to DIRTY House.'.match(/(?<match>DIRTY)/)[:match] # => "DIRTY"

However, if it does not match, a NoMethodError will occur.

 'Welcome to DIRTY House.'.match(/(?<match>CLEAN)/)[:match] # => NoMethodError: undefined method `[]' for nil:NilClass

As a countermeasure, if nothing is found, substitute an empty array with || .

 ('Welcome to DIRTY House.'.match(/(?<match>CLEAN)/) || {})[:match] # => nil

Now returns nil instead of NoMethodError.

何か質問、悩み事、相談などあればLINEオープンチャットもご利用ください。

2019-04-16