:date: 2020-04-30

========================
Thursday, April 30, 2020
========================

.. 30.04.2020 02:20-04:05
   add cal.Event.positions field to layout

I recorded a next screen cast about calendar management in :ref:`presto`, also
about the :attr:`municipality` field.

https://youtu.be/NwpJH349D18

But I had some work before Lino was ready for this.  Because I discovered that
the filter parameters in calendar views were still being ignored.  This caused a
whole series of internal changes.

We have a new plugin parameter :attr:`lino_xl.lib.calview.Plugin.params_layout`,
which specifies the layout of the table parameters used by all calendar views.

calview.EventsParameters must not call Event.setup_parameters but
Events.setup_parameters.

This change in turn caused the problem that setup_parameters requires Actor.model to be resolved.
Until now kernel called class_init() on each actor, and class_init() called setup_parameters().
But calview.EventsParameters for some reason is coming before cal.Events.
To fix this, I splitted Actor.class_init into a new method :meth:`init_layouts`

Now the other problem: all those methods that map parameter values to queryset
filters.  The param_values AttrDict contains only values for those parameters
that are being used.  Which is a problem.

There was no more need for a separate :meth:`calendar_param_filter` method on
:class:`cal.Event`, so I removed it.

I also understood why I had to write::

    if pv.get('project__municipality'):

instead of the usual::

    if pv.project__municipality:

The latter syntax failed for tables on cal.Event that don't have the field
mentioned in their params_layout.  Because, yes, remote fields are kind of
volatile fields and get created on the fly when a layout asks for them.  That's
why, when you want to use a remote field as table parameter, you should also
write a setup_parameters method on your model::

    from lino.core.fields import make_remote_field

    @classmethod
    def setup_parameters(cls, params):
        super(Event, cls).setup_parameters(params)
        params['project__municipality'] = make_remote_field(cls, 'project__municipality')

    @classmethod
    def get_request_queryset(cls, ar, **filter):
        qs = super(Event, cls).get_request_queryset(ar, **filter)
        pv = ar.param_values
        if pv.project__municipality:
            places = pv.project__municipality.whole_clan()
            qs = qs.filter(project__isnull=False, project__city__in=places)
        return qs


Before committing, I had once more some fun with writing documentation about
these things. I am still far from having finished.  I added the ``--keep-going``
option to :cmd:`inv bd`.