Sunday, June 21, 2020

Worker has no field named ‘purchase_account_id

The contacts.Worker model in Lino Presto does have a field purchase_account (which is a FK and therefore creates a field purchase_account_id).

The purchase_account is a bit special because it is injected automatically by the lino_xl.lib.ledger.choicelists module where we have this code:

    'P', _("Purchases"), 'purchases', dc=CREDIT,
    invoice_account_field_label=_("Purchase account")

Every trade type potentially injects a series of fields into certain models. One of these fields is given by invoice_account_field_name.

Later in the same module we define a receiver for the pre_analyze event that injects the purchase_account field into contacts.Partner:

def inject_tradetype_fields(sender, **kw):
    for tt in TradeTypes.items():
        if tt.invoice_account_field_name is not None:
                'contacts.Partner', tt.invoice_account_field_name,
                    related_name='partners_by_' + tt.invoice_account_field_name,
                    blank=True, null=True))


My first guess was to suspect the lino.core.inject.inject_field() function, which accesses undocumented Django internals and therefore might be broken. But the problem occurs also when I downgrade my Django to 2.2.5 (the version used on their production site), so this is not the explanation.

What’s the trigger? Why does this problem occur only in Lino Presto and in no other application? Presto isn’t the only application that uses lino_xl.lib.ledger.

Maybe the inheritance scheme? In presto (see lino_presto.lib.contacts) we have custom Partner and Person models, and then define Worker as a subclass of our custom Person:

from lino_xl.lib.contacts.models import *
class Partner(Partner, mixins.CreatedModified):
class Person(Partner, Person):
class Worker(Person, SSIN, Plannable):

But nothing has changed with these things between the version on their production site and the current version.

I gave up the ticket for now, hoping that Tonis or Hamza have some inspiration.