问对于Odoo11，当只读控件字段没有值时，如何去除false值？

EN

<group>
    <field name="partner_id" required="1"
           string="Customer"
           domain="[('customer', '=', True),('internal_user', '=', False)]"
           context="{'search_default_customer': 1,
            'default_name': partner_name, 'default_street': street,
            'default_street2': street2, 'default_city': city,
            'default_state_id': state_id, 'default_zip': zip,
            'default_country_id': country_id, 'default_function': function,
            'default_phone': phone, 'default_mobile': mobile,
            'default_email': email_from,
            'default_user_id': user_id, 'default_team_id': team_id, 'default_website': website}"/>

    <field name="email_from" string="Email" widget="email" readonly="1"/>    
    <field name="phone" widget="phone" readonly="1"/>
    <field name="website" widget="url" placeholder="e.g. www.sunarctechnologies.com"
       readonly="1"/>
</group>