A default flag on a table in rails -

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i have simple table/model in rails, vat_rates. administrators need able select one, , 1 of these default rate selected on html form when creating new related items items have vat_rate_id. have added boolean default column vat_rates table.

what straight forward, , rails-like way ensure 1 vat_rate can default 1 @ time?

i'm not bothered if there no defaults, there no more one.

you add custom validation method this , return error if vat_rate selected default already. alternatively can add before_update or after_update callback this set other default values false on update.


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