:date: 2019-10-15

=========================
Tuesday, October 15, 2019
=========================


I fixed a little bug which caused the following traceback when trying to show
the detail of an excerpt::

  AjaxExceptionResponse TypeError: __str__ returned non-string (type __proxy__)
  in request GET /api/excerpts/MyExcerpts/6?_dc=1571102296305&lv=1571101922.83524&pv=&pv=&pv=&pv=1&pv=&an=detail&rp=ext-comp-2534&fmt=json
  TRACEBACK:
    File "/home/luc/virtualenvs/py3/lib/python3.6/site-packages/django/core/handlers/base.py", line 113, in _get_response
      response = wrapped_callback(request, *callback_args, **callback_kwargs)
    File "/home/luc/virtualenvs/py3/lib/python3.6/site-packages/django/views/generic/base.py", line 71, in view
      return self.dispatch(request, *args, **kwargs)
    File "/home/luc/virtualenvs/py3/lib/python3.6/site-packages/django/views/generic/base.py", line 97, in dispatch
      return handler(request, *args, **kwargs)
    File "/home/luc/virtualenvs/py3/lib/python3.6/site-packages/django/utils/decorators.py", line 45, in _wrapper
      return bound_method(*args, **kwargs)
    File "/home/luc/virtualenvs/py3/lib/python3.6/site-packages/django/utils/decorators.py", line 142, in _wrapped_view
      response = view_func(request, *args, **kwargs)
    File "/home/luc/work/lino/lino/modlib/extjs/views.py", line 548, in get
      datarec = ar.elem2rec_detailed(elem)
    File "/home/luc/work/lino/lino/core/requests.py", line 1036, in elem2rec_detailed
      rec.update(title=ar.get_breadcrumbs(elem))
    File "/home/luc/work/lino/lino/core/requests.py", line 1060, in get_breadcrumbs
      return list_title + u" » " + self.get_detail_title(elem)
    File "/home/luc/work/lino/lino/core/requests.py", line 986, in get_detail_title
      return self.actor.get_detail_title(self, elem)
    File "/home/luc/work/lino/lino/core/actors.py", line 1186, in get_detail_title
      return str(obj)
  Bad Request: /api/excerpts/MyExcerpts/6


About rendering headers and footers in weasyprint
=================================================

Before working on :ticket:`3266`  I did some research work and optimizations
about how  headers and footers should be configured in
:mod:`lino.modlib.weasyprint` templates (:ticket:`3267`).

Here is how the :xfile:`excerpts/base.weasy.html` file did it until now::

  @page {
      margin: 10mm; margin-top: 15mm; margin-bottom: 15mm;
      size:{%- block pagesize %}landscape{%- endblock %};
      @bottom-right {
          vertical-align: top;
          content: counter(page) ' / ' counter(pages);
      }
      font-family: "Liberation sans", "arial";
      font-size: 10pt;
  }

The  `@page <https://www.quackit.com/css/at-rules/css_page_at-rule.cfm>`__ and
`@bottom-right
<https://www.quackit.com/css/at-rules/css_bottom-right_at-rule.cfm>`__ at-rule
are used to apply styles for *paged media* (i.e. not continuous media).

List of all page-margin properties:
https://www.quackit.com/css/at-rules/css_page-margin_properties_list.cfm

More readings:

- https://www.quackit.com/css/properties/css_content.cfm
- https://weasyprint.readthedocs.io/en/latest/tips-tricks.html#include-header-and-footer-of-arbitrary-complexity-in-a-pdf
- https://stackoverflow.com/questions/39941967/generate-pdf-with-weasyprint-having-common-header-footer-and-pagination
- https://github.com/Kozea/WeasyPrint/blob/gh-pages/samples/invoice/invoice.css
- https://gist.github.com/pikhovkin/5642563 complex headers

- TIL: Setting the height attribute in HTML is called a "presentational hint"
  and it's now recommended not to use them and use CSS instead.
  Presentational hints are ignored by WeasyPrint by default,
  but you can handle them using the --presentational-hints CLI parameter.
  https://github.com/Kozea/WeasyPrint/issues/872

After reading all these I say: No, we currently don't need arbitrary "complex"
HTML in headers and footers. The standard system with at-rules works well for
us.

Changes in Lino and XL:

- The :xfile:`excerpts/base.weasy.html` file
  I extended this a bit and moved duplicated css definitions from
  :xfile:`excerpts/base.weasy.html` to :xfile:`weasyprint/base.weasy.html`.
  The new ``bottomleft`` and ``bottomright`` blocks are expected to contain the
  `content` property for their respective element.

You can now automagically add a logo to all your weasyprint documents by adding
local a :xfile:`config` directory with a subdirectory :file:`weasyprint`
containing a file named :file:`logo.jpg`.

Changes in the final report for :ref:`avanti`
=============================================

Here we go for :ticket:`3266`.
This is basically a few more changes in the template for the final report.
Also I switched build method from appypod to weasy2pdf.
And some minor changes in :ref:`xl`:

:meth:`lino.core.requests.BaseRequest.get_printable_context` adds a new function
:func:`activate_language` to set the language for the remaining part of the
template. This is because they want final reports printed in German even if the
clients contact language is different.

Until now :ref:`avanti` defined two
:class:`lino_xl.lib.clients.KnownContactTypes`
``general_assistant`` and
``integ_assistant``.
These have been replaced by a single entry ``social_center``.
"Social assistant" and "Integration agent" are now two functions (:class:`lino_xl.lib.contacts.RoleType`)
added by the :fixture:`std` fixture of :mod:`lino_avanti.lib.avanti`.

New method :class:`lino_xl.lib.clients.KnownContactType.get_contacts` (i.e. get
them all, not just one) is now used instead of
:class:`lino_xl.lib.clients.KnownContactType.get_contact`.

Summary layout of :class:`lino_xl.lib.cv.HistoryByPerson` was not very readable:
added a colon behind each field label, and the field value is now  bold.
A bug in that same summary always inserted an empty bullet at the beginning of the list.


Who's behind weasyprint?
========================

Nice: The `Kozea community <https://community.kozea.fr/>`__ (maintainers of
weasyprint) describes itself with the following words:

  We build open source software that you will love

  After years and years of extremely intense research (and endless nights
  drinking in pubs with friends), we've found the three most important rules of
  free software development:

    1. have good ideas
    2. forget limits
    3. build step by step

  Having good ideas is hard, that's why we chose to rely on your ideas (they're
  much better than ours, aren't they?). Our job is to blindly follow the two other
  rules, and we think that we're doing that quite well according to what we got so
  far:

Deep in my heart I feel that I agree with them...


Testing it on the preview site
==============================

- MultiValueDictKeyError: 'uuid' after reading a beid card.

- After merging two persons, Lino says "Kann Klient XYZ (2248) nicht löschen
  weil 52 Anwesenheiten darauf verweisen.". That's normal. You should not merge
  Persons as long as one of them is also a client because Lino won't merge the
  client-specific slave tables.  But when deleting the person, it will also want
  to delete the client, and that won't work because related data exists.