When to use api.one and api.multi in odoo | openerp?

Question

Recently odoo (formerly OpenERP) V8 has been released. In new API method decorators are introduced. in models.py methods needs to be decorated with @api.one

Answer 1

@api.model #When the record data/self is not as relevant. Sometimes also used with old API calls.
def model_text(self):
    return "this text does not rely on self"

@api.multi #Normally followed by a loop on self because self may contain multiple records
def set_field(self):
    for r in self:
        r.abc = r.a + r.b

@api.one #The api will do a loop and call the method for each record. Not preferred because of potential problems with returns to web clients
def set_field(self):
    self.abc = self.a + self.b