The arel_extensions gem has a couple of bugs...
DateSubdoesn't work:
(table[:column] - 10.hours).to_sql
# => NoMethodError: undefined method `to_sql' for nil:NilClass- For MySQL,
DateAddgenerates a double-minus when given a negative duration:
(table[:column] + -10.hours).to_sql
# => DATE_ADD(`tmp_modules_fbt_travel_diaries`.`created_at`, INTERVAL --36000 second)PR to fix this one: Faveod/arel-extensions#5