Hi i want to create a age calculator in openerp.

in my age calculator, if i select date of birth before 100 years; here i want to show a alert message like "Please select a date of birth in between 100 years... thankyou"

here i include my programs,

in my module.py

from datetime import date,datetime
from time import strptime
from dateutil import parser
from openerp.osv import osv, fields

    class jebatraining(osv.osv):
        _name = "age_calculator"
        _description = "Age Calculator"

        def onchange_getage(self,cr,uid,ids,dob,context=None):

            current_date=datetime.now()

            current_year=current_date.year

            birth_date=parser.parse(dob)

            if (current_year>=birth_date.year):

                current_age=current_year-birth_date.year

            else:
                current_age=0

                return {'value':{'age': current_age}} 

        _columns = {

            'dob':fields.date('Date of Birth', required=True),
            'age':fields.integer('Age', size=3),

            }
    jebatraining()

in my module_view.xml

<record id="age_calculator_form" model="ir.ui.view">
    <field name="name">jebatraining.form_view</field>
    <field name="model">age_calculator</field>
    <field name="type">form</field>
    <field name="arch" type="xml">
        <form string="age calculator">

            <field name="dob" on_change = "onchange_getage(dob)" string="Date of Birth"/> 
            <field name="age" string="Age"/>

        </form>
    </field>
 </record>

anyone help me. thanks friends................