ruby - Validating minutes and seconds in Rails -

i'm trying validate time based attribute called duration 1 of models. attribute, accept along lines of 01:30 valid value. goal have 4 digit time-code (minutes , seconds) colon in between two. both minutes , seconds limit in range 59 , cannot have 00:00 value. regex have doesn't seem work:

validates :duration, presence: true, format: {with: /a([0-9]|0[0-9]|1[0-9]|2[0-3]):[0-5][0-9]z/} 

use negative lookahead(?!00:00), rest of regex simple minutes/seconds validation.

/\a(?!00:00)[0-5][0-9]:[0-5][0-9]\z/ 

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if subject =~ /\a(?!00:00)[0-5][0-9]:[0-5][0-9]\z/     # successful match else     # match attempt failed end 

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regex demo