def validate_username(form, field):
form.user = UserMgr.one(username=field.data)
if form.user is None:
msg = field.data + " isn't a registered user."
raise val.StopValidation(msg)
def validate_username(form, field):
if UserMgr.one(username=field.data):
msg = "Username {} is taken".format(field.data)
raise wtforms.ValidationError(msg)
