Hello,

I am new to Odoo and I struggle with the new Odoo API. I am trying to create new records on a Many2One field in an @api.onchange method. It is a custom module so I will simplify by providing a made up example. 

Say that I am building a new Order that has Lines. The lines are defined via a Many2One field called 'line':

class Order(models.Model):

    name="mymodule.order"

    line = fields.One2many('mymodule.line',
                                inverse_name="order_id",         
                                string="Lines")

    partner_id = fields.....

    .....

I want to generate new lines as soon as the user selects or changes the partner_id of the order. To do so, I have implemented an @api.onchance method that looks somewhat like this:

@api.onchange('partner_id')
 def onchange_equipment_type_id(self):
        """ Updates the order lines"""
        if self.line:
            self.line.unlink()
        for val in self.bogus_values: #some bogus list that supposedly tells me how many lines I need to create
            self.line.create((0, 0, {'name':val.name, 'order_id':self.id, ....}))

The above approach does not work. First of all, as far as I understand CREATE will actually create records to the DB. I do not want that. I simply want to add some order lines as if I clicked few times on 'Add an item' in a table. The actual creation of the lines shall happen when the user clicks the Save button on the order. So what method shall I use? How can I 'add' records to the line field without writing to the DB at this point? 

The second problem that I face is that self.id is NewId. Now as per my understanding this is normal for New records. But I actually get self.id as NewID even for entries that have been saved and I open them in edit mode. Anyways, for the case when the order has not been saved yet, I still need to add lines. So my major issue is how to add lines to my Many2One field as part of my onchange method without triggering a DB write. 

I hope that my question makes some sense. 

Thank you in advance for your help.