Hi  Varinder Kaur,

Constrains will call only at the time of field values change, otherwise it will not be called.

My constraint code like below(it will be called while changing phone no. only)

@api.constrains('mobile')
def check_mobile_no(self):
    if self.mobile:
        record_count = self.search_count([('mobile', '=', self.mobile)])
        # Need to mention Greater Than 1(Because self contains current record also)
        if record_count > 1:
            raise ValidationError("Mobile no. already exist.")

Thanks.