module ActiveRecord::SignedId::ClassMethods

def find_signed!(signed_id, purpose: nil)

User.find_signed! signed_id # => ActiveRecord::RecordNotFound
User.first.destroy
signed_id = User.first.signed_id

User.find_signed! "bad data" # => ActiveSupport::MessageVerifier::InvalidSignature

=== Examples

the valid signed id can't find a record.
or has been tampered with. It will also raise an +ActiveRecord::RecordNotFound+ exception if
exception if the +signed_id+ has either expired, has a purpose mismatch, is for another record,
Works like find_signed, but will raise an +ActiveSupport::MessageVerifier::InvalidSignature+ 
def find_signed!(signed_id, purpose: nil)
  if id = signed_id_verifier.verify(signed_id, purpose: combine_signed_id_purposes(purpose))
    find(id)
  end
end