# Monday, May 23, 2016¶

## Duplicating a Referrable¶

When duplicating a database object, Lino now calls the on_duplicate method on the master before saving it for a first time.

This change is needed because otherwise lino.mixins.Referrable.on_duplicate() has no chance to do its work. Duplicating a Referrable, until now, failed with a IntegrityError (1062, "Duplicate entry 'XXX' for key 'ref'") in any database other than SQLite (ticket #934).

## Run unit tests in a MySQL demo database¶

In order to test this change, I added the new method get_database_settings on lino.core.site.Site so that I can run the unit test suite on MySQL instead of SQLite.

I tried it and discovered that many test cases fail because of the different alphabetical ordering between SQLite and MySQL. So this is not feasable.

What is feasable (but not yet used) is to use your own variant of the settings module and to write test cases which explicitly use this. This requires of course additional effort because tests will work only if a MySQL database and user with appropriate permissions has been created.

An example for this is lino_welfare.projects.eupen.settings.mysql. Yes, get_database_settings is admittedly not very necessary for this example.

## Error when printing a sales invoice¶

When trying to print a sales invoice yesterday with Alexa, we got this error message:

EvaluationError: Error while evaluating the expression “table(obj.get_print_items(ar))” defined in the “from” part of a statement.

NotImplementedError: inside

Today I checked the Lino logfile and saw that the message was actually:

NotImplementedError: <dl> inside <text:p>

We just didn’t see the complete message because our browser interpreted the tags. In order to avoid this in the future, lino.core.requests.BaseRequest.error() now escapes the error message. I am not sure at all whether this is the right place, and I did not write any test case to verify it.

The reason was then clear: Alexa had manually removed some dates from the description of one item:

Geplante Daten:
24.05.16, 31.05.16, 07.06.16, 14.06.16, 21.06.16, 13.09.16, 20.09.16, 27.09.16, 04.10.16, 11.10.16, 18.10.16, 25.10.16, 08.11.16, 15.11.16, 22.11.16,


She didn’t know that the leading space was important. With the following description our problem was solved:

Geplante Daten:
24.05.16, 31.05.16, 07.06.16, 14.06.16, 21.06.16, 13.09.16, 20.09.16, 27.09.16, 04.10.16, 11.10.16, 18.10.16, 25.10.16, 08.11.16, 15.11.16, 22.11.16,


This raises of course the question about how to explain reSTructuredText to a non-programmer.

## Item descriptions¶

I added a section “Scheduled dates” to the How Lino Voga generates invoices specs in order to work on ticket #936. Reproducing this problem was the most time-consuming part of my day.

## Miscellaneous¶

I changed the name rt.modules to rt.models. But the old name will probably remain some time for backward compatibility.

I discovered the tablib project and started to think whether it makes sense to use this in Lino. #935

## Lino now supports generic relations¶

The new invoicings attribute of an Invoiceable is my first usage of Django’s GenericRelation. And I discovered that Lino until now did not support these very well because if you define one, Lino will include it as a virtual field in your wildcard elements and then raise an exception because it cannot create a layout element for it.

## Lino Presto going on¶

I continued on #897. lino_presto.lib.clocking.