diff options
| -rw-r--r-- | railties/guides/source/active_record_validations_callbacks.textile | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/railties/guides/source/active_record_validations_callbacks.textile b/railties/guides/source/active_record_validations_callbacks.textile index 349d02c1f6..88c4481e5e 100644 --- a/railties/guides/source/active_record_validations_callbacks.textile +++ b/railties/guides/source/active_record_validations_callbacks.textile @@ -531,7 +531,7 @@ Person.new.valid? => ActiveModel::StrictValidationFailed: Name can't be blank h3. Conditional Validation -Sometimes it will make sense to validate an object just when a given predicate is satisfied. You can do that by using the +:if+ and +:unless+ options, which can take a symbol, a string or a +Proc+. You may use the +:if+ option when you want to specify when the validation *should* happen. If you want to specify when the validation *should not* happen, then you may use the +:unless+ option. +Sometimes it will make sense to validate an object just when a given predicate is satisfied. You can do that by using the +:if+ and +:unless+ options, which can take a symbol, a string, a +Proc+ or an +Array+. You may use the +:if+ option when you want to specify when the validation *should* happen. If you want to specify when the validation *should not* happen, then you may use the +:unless+ option. h4. Using a Symbol with +:if+ and +:unless+ @@ -583,6 +583,20 @@ end All validations inside of +with_options+ block will have automatically passed the condition +:if => :is_admin?+ +h4. Combining validation conditions + +On the other hand, when multiple conditions define whether or not a validation should happen, an +Array+ can be used. Moreover, you can apply both +:if:+ and +:unless+ to the same validation. + +<ruby> +class Computer < ActiveRecord::Base + validates :mouse, :presence => true, + :if => ["market.retail?", :desktop?] + :unless => Proc.new { |c| c.trackpad.present? } +end +</ruby> + +The validation only runs when all the +:if+ conditions and none of the +:unless+ conditions are evaluated to +true+. + h3. Performing Custom Validations When the built-in validation helpers are not enough for your needs, you can write your own validators or validation methods as you prefer. @@ -1107,7 +1121,7 @@ Post destroyed h3. Conditional Callbacks -As with validations, we can also make the calling of a callback method conditional on the satisfaction of a given predicate. We can do this using the +:if+ and +:unless+ options, which can take a symbol, a string or a +Proc+. You may use the +:if+ option when you want to specify under which conditions the callback *should* be called. If you want to specify the conditions under which the callback *should not* be called, then you may use the +:unless+ option. +As with validations, we can also make the calling of a callback method conditional on the satisfaction of a given predicate. We can do this using the +:if+ and +:unless+ options, which can take a symbol, a string, a +Proc+ or an +Array+. You may use the +:if+ option when you want to specify under which conditions the callback *should* be called. If you want to specify the conditions under which the callback *should not* be called, then you may use the +:unless+ option. h4. Using +:if+ and +:unless+ with a +Symbol+ |