Triggers in OpenERP

Hi Every one,

I was wondering that, if there is any triggers concept in OpenERP. In related ERP systems such as Oracle, Triggers are very common being used on their forms.

In OpenERP, a related concept is the functional fields. However, Calculation with them is not that much perfect (as I have understood).

The reason is that, whenever, I try to save the data in a form (by pressing the Save Button), only then the values in different functional fields are calculated and saved in the corresponding fields.

Can we have some type of Pre-Trigger and Post-Trigger behavior in the sense that we can have a function which is called, as the control is being passed to the field on the form, Also, when the control is exited, we can also call another function.

I am following the following code, please help in identifying where I can change to get the aforementioned behavior:

class entrytest(osv.osv):

    def _get_company_currency(self, cr, uid, ids, field_name, arg, context={}):
        result = {}
        for rec in self.browse(cr, uid, ids, context):
            result[rec.id] = (rec.Percentage.id,rec.Percentage.Percentage)
        return result

    def _get_company_currency1(self, cr, uid, ids, field_name, arg, context={}):
        result = {}
        for rec in self.browse(cr, uid, ids, context):
            result[rec.id] = (rec.Percentage.id,rec.Percentage.CGPA)
        return result

    def _get_company_currency2(self, cr, uid, ids, field_name, arg, context={}):
        result = {}
        for rec in self.browse(cr, uid, ids, context):
            result[rec.id] = rec.interviewmarks + rec.Percentage.Percentage
        return result

    _name = "entrytest.entrytest"
    _description = "Entry Tesr Discription"
    _columns = {
        'name': fields.char('Name1', size=64),
        'Percentage': fields.many2one('student_qualification.student_qualification', 'Per'),
        'interviewmarks': fields.float('INterview Marks', required=True),
        'CGPA': fields.many2one('student_qualification.student_qualification', 'CGPA'),
        'line_id1': fields.function(_get_company_currency, method=True, type='many2one', relation='student_qualification.student_qualification', string='Percentage'),
        'line_id2': fields.function(_get_company_currency1, method=True, type='many2one', relation='student_qualification.student_qualification', string='CGPA'),
        'line_id3': fields.function(_get_company_currency2, method=True, type='many2one', relation='student_qualification.student_qualification', string='Total Marks'),

    }
entrytest()

Thanking you in advance.
Regards,
MM Alam