This is probably an easy question, but I'm looking for a way to validate a field if it is given, but let it pass if it is empty. Currently, the following validator doesn't allow an empty string to be passed in. Is there an argument to the IS_EMAIL validator and other validators that allow it to accept empty values?
db.define_table('entity',
Field('email', 'string', length=64, required=False),
)
db.entity.email.requires = IS_EMAIL(error_message=T('Invalid email
address.'))
