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Friday, February 26, 2016
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I started to write documentation for the new module
:mod:`lino_xl.lib.invoicing`.

A first problem is that this plugin is not used by
:mod:`lino_cosi.projects.std`, so autosummary fails to import it::

    WARNING: [autosummary] failed to import u'lino_xl.lib.invoicing.models': no module named lino_xl.lib.invoicing.models

Since autosummary itself does not show me the error. In order to see
this message I had to simulate what autosummary does:

>>> from lino import startup
>>> startup('lino_cosi.projects.std.settings.doctests')
>>> import lino_xl.lib.invoicing.models  #doctest: +ELLIPSIS
Traceback (most recent call last):
...
AttributeError: AttrDict instance has no key 'invoicing' (keys are ...)

So the failure was caused by this code::

    invoice = models.ForeignKey(
        dd.plugins.invoicing.voucher_model, null=True, blank=True)

Yes, this is a common problem when using Sphinx autodoc to generate
API documentation for a Django :xfile:`models.py` file. These modules
are (often) not importable by a process which has activated Django
using a settings module that does not include the module in its
:setting:`INSTALLED_APPS`.

A quick workaround is to add :mod:`lino_xl.lib.invoicing` to the
:meth:`get_installed_plugins <lino.core.site.Site.get_installed_plugins>` of
:mod:`lino_cosi.projects.std`. 

This solution has the disadvantage (or advantage?) that every
:ref:`cosi` site will have these two tables (:class:`invoicing.Plan
<lino_xl.lib.invoicing.models.Plan>` and :class:`invoicing.Item
<lino_xl.lib.invoicing.models.Item>`) in their database, even if
they don't use the automatic invoicing feature.