ruby - Performing rails model validations before encrypting attribute with attr-encrypted gem -

i have encrypted attribute (let's call @model.encrypted_attribute) in 1 of models. before adding encryption had following validation in model:

validates_length_of :attribute, :minimum => 11, :maximum => 11, :allow_blank => true,  :message => "| attribute must 11 digits long." 

i had method ran before_save gsub out non-numerical characters attribute. now, however, can't figure out how to:

1. run gsub!(/\d/, '') on attribute before encrypted , saved or run afterwards , have attr-encrypted re-encrypt @model.attribute value , write database. can strip characters, not re-encrypt/save.

2. run validation on non-encrypted value of attribute before saving. have tried adding following code in before_block different error (undefined method '12345678' #<spree::order:0x007fae02011cd0):

     def format_attribute     validates_length_of self.attribute.gsub(/\d/, ''), :minimum => 9, :maximum => 9, :allow_blank => true, :message =>     "| attribute should 9 digits long." end     

does have idea of how can achieve 1 or both of above or, @ least, set custom method run before attr_encrypted thing.

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leaving 2 above people come while searching solution can found @ validation of encrypted data