Hi,

I'm trying to customize a python code within Odoo V12 which is passing details from an ticket into a bill.

This is working so far (not coded by myself):

def _prepare_invoice_line_details(self, line, desc_rule):
        details = []
        if desc_rule[0] == '1':
            employee=self.env['hr.employee'].search([('id','=',line.employee_id.id)])
            details.append("\n" + employee.name)
            details.append(datetime.strftime(datetime.strptime(fields.Date.to_string(line.date), '%Y-%m-%d'), '%d.%m.%Y'))
        if desc_rule[1] == '1':
            details.append("%s %s" % (line.unit_amount, line.product_uom_id.name))
            details.append(line.x_studio_ort_der_leistungserbringung)
        if desc_rule[2] == '1':
            details.append(line.x_studio_zeitraum + "\n" + line.name)
        return details

...
...
...

It's almost the same as here: https://code.compassfoundation.io/odoo/care_center/blob/ba5b4ee9d15f9dcf070bdde808c0eae7add1db9e/care_center_timesheets/models/sale_order.py with just some additional values.

It's just collecting the information from an ticket within the description columns and passing it to the billing process.
Now I have added 2 additional columns and they should also be passed to this function. I have added these 2 fields with the studio manager which was quite simple and also the first field was quite easy to handle by adding this:

details.append(line.x_studio_abrechnungsart)

But with the other column I'm struggling.
It's a related field which is actually just the Ticket title + ID:

I can't attach an screenshot, so I'm trying to "draw" it:

----------------------------------------------------------------------------------------
date | employee | description | billing type | ticket | duration |

21.04.20 | Gerad | broken login data | goodwill | Test Ticket (#1620) | 0:30

----------------------------------------------------------------------------------------

(so it's regarding the fat formatted, billing type I was able to do by myself, unfortunately "ticket" (underlined) I wasn't able) 

Note: This filed will later be marked as invisible, I just abuse the field because I thought it will be much more easier to get the needed value because I can use following line as an template:

employee=self.env['hr.employee'].search([('id','=',line.employee_id.id)])

So I have tried to do the following:

helpid=self.env['helpdesk.ticket'].search([('helpdesk_ticket_id','=',line.helpdesk_ticket_id.id)])
details.append(helpid)

But now, when I try to generate the bill, I'm receiving this error message:

raise ValueError("Invalid field %r in leaf %r" % (left, str(leaf)))
ValueError: Invalid field 'helpdesk_ticket_id' in leaf "<osv.ExtendedLeaf: ('helpdesk_ticket_id', '=', 1620) on helpdesk_ticket (ctx: )>"

As you can see there is the correct Ticket-ID (1620) but I wasn't able to fix this.

Additional information: It would also be no problem to get the Ticket ID anyway else, as already mentioned I only abusing this extra column to display the ticket title + ID.

It would be also great if also the ticket-title (in the example "test ticket") will be fetched and not only the ID (1620 in the example), but if not it's also ok.

Can somebody please assist and tell me what I'm doing wrong here?

Best regards.