Wednesday, September 6, 2017

Django querysets with UNION not supported on MariaDB

Yes, it seems that Django querysets with UNION are not supported on MariaDB. But I fixed the problem by changing to PostgreSQL which supports them.

Possible side effect also on systems using MySQL: the initdb command now calls migrate twice: once without and once with the –run-syncdb option. The help text of that option says that it “Creates tables for apps without migrations”, but I am not sure what it does for apps with migrations. It seems that this has changed recently.

I could not test whether they work on MySQL because switching from MariaDB to MySQL is not trivial on Jessie, and anyway MySQL is no longer available on Debian Stretch (source).

Try PostgreSQL. My notes while doing

It is better to have your locales correctly working before you install postgresql:

$ sudo apt-get install postgresql postgresql-client
Setting up postgresql-common (165+deb8u2) ...
locale: Cannot set LC_ALL to default locale: No such file or directory
Adding user postgres to group ssl-cert

Creating config file /etc/postgresql-common/createcluster.conf with new version

Creating config file /etc/logrotate.d/postgresql-common with new version
Building PostgreSQL dictionaries from installed myspell/hunspell packages...
Removing obsolete dictionary files:
Setting up postgresql-9.4 (9.4.13-0+deb8u1) ...
Error: The locale requested by the environment is invalid.
Error: could not create default cluster. Please create it manually with

  pg_createcluster 9.4 main --start

or a similar command (see 'man pg_createcluster').
update-alternatives: using /usr/share/postgresql/9.4/man/man1/postmaster.1.gz to provide /usr/share/man/man1/postmaster.1.gz (postmaster.1.gz) in auto mode

$ sudo dpkg-reconfigure locales
$ pg_createcluster 9.4 main --start

Both the default database user and default database are called postgres.

$ sudo su - postgres

Create a PostgreSQL user and database:

$ createuser django
$ createdb -O django mydb

Install Python packages:

$ pip install psycopg2

Set password:

$ sudo su - postgres
$ psql mydb

Show eisting users:

spzdb=# \du
                             List of roles
 Role name |                   Attributes                   | Member of
 django    |                                                | {}
 postgres  | Superuser, Create role, Create DB, Replication | {}

SELECT rolname FROM pg_roles;
ALTER ROLE django with password '123';

Now let’s go:

$ python run snapshot/

There were of course a few surprises because this was the first time for Lino to collaborate with PostgreSQL:

  • Exception: Not tested for ‘django.db.backends.postgresql’

  • django.db.utils.OperationalError: cannot drop the currently open database

    Thanks to stackoverflow where I found that the following should do:

    select tablename from pg_tables where schemaname = 'public';

    I then still had a “django.db.utils.ProgrammingError: relation “django_content_type” does not exist” which disappeared after a manual migrate:

    $ python migrate
    Operations to perform:
      Apply all migrations: contenttypes, sessions
    Running migrations:
      Applying contenttypes.0001_initial... OK
      Applying contenttypes.0002_remove_content_type_name... OK
      Applying sessions.0001_initial... OK

    It seems that this was because of a syntax error in my DROP TABLE statement. Seems fixed now.

  • The restore seems very slow. Is there a way to bypass integrity checks? I read this thread and used DISABLE TRIGGER ALL, but still it takes half an hour to restore their database:

    real     29m18.932s
    user     23m10.648s
    sys      0m50.460s

Optimizing entry of invoices

I wrote an action lino_xl.lib.sales.models.MakeCopy for lino_xl.lib.sales.models.VatProductInvoice. Lydia must to enter a hundred invoices, and this action will make her task less painful. Now she needs only one mouse click per invoice (on the [⁂] button), everything else can be done using the keyboard.


More user instructions:

  • If you leave empty the fields “Tariff” and “Total incl VAT”, then Lino copies the content of the current invoice to the new invoice.

  • If you specify a “Total incl VAT”, then the new invoice will have only one row. If you leave product empty, then that row will have the product of the first row. NB: the verbose_name of products.Product is “Tariff” in Lino Tera.

Implementation notes:

This is a quick first solution. TODO: how to implement something similar more generally also for other invoice models.

This is a dialog action. TODO: write general documentation.

The action button is currently [⁂]. The button must in the workflow_actions (cannot be in the toolbar) because otherwise the default values are not filled in (#1336).

I fixed a bug in linoweb.js which caused the ActionFormPanel to not submit when ENTER key was pressed. TODO: check whether this needs to be done in ExtJS 6 as well.

Courses with two teachers

Johanna told me that they have cases where two teachers share one course. Ticket #2042. One idea is to create a user for every effective pair of teachers and give each individual teacher an Authority to work as that user.

Misc Optimizations for Lino Avanti (#2035):

  • Added a panel “Presences” ( to avanti.ClientDetail

  • The chooser for now shows only active courses (i.e. whose is True.

  • now shows only active courses by default. Users can see them all by opening the slave table in its own window and setting show_active parameter to empty. As a result, also StatusReport (which uses this table) shows only active courses.


  • Lehrer sollen die Liste “Alle Aktivitäten” nicht sehen

  • Anna Fallalala kann noch immer nicht gelöscht werden, weil sie jetzt noch Anwesenheiten hat. Und die sind nirgendwo sichtbar.

  • Einfügen in Einschreibungen pro Klient : abgeschlossene und inaktive Kurse sollten dort nicht angezeigt werden.

  • Im Statusbericht auch nur die aktiven Kurse anzeigen (also abgeschlossene und inaktive Kurse nicht)

  • Aktivitäten : Einfügen in Themen : ist nicht toll.​


  • Entwicklungsschritte “Bilanzgespräch” und “Einschreibung in Kurse” kann mehrmals pro Klient vorkommen, Lino schimpft dann aber.

  • Vereinbarung ausdrucken via Lino : Modul “Auszüge” aktivieren. Johanna schickt mir ein Modell

Tables with a detail_layout but no insert_layout

API change as a side effect of above: I removed the rule that Lino used detail_layout for the insert window as well when there’s a detail_layout but no insert_layout. Manually tested on Looks nice. Ticket #2043.