Look and fix some DB model issues

[lw]

I think some DB models (i.e. those classes in cms.db) have some strange fields definitions. For example the User.ip field is nullable but we usually use the '0.0.0.0' string to mean "no IP address assigned". Likewise User.email is almost never used, thus left blank, but it's not nullable. I suspect other such issues are around, even of other kinds. We should take a look at all models and fix the ones we find.

[giomasce]

I'm of course in favor, in general, to such changes and agree that the two cases you indicate are to be fixed.

[bblackham]

Can I suggest for User.ip, that instead of hard-coding '0.0.0.0', we actually just use NULL or a specific IP(v4 or v6) address? (i.e. make NULL the new '0.0.0.0', as '0.0.0.0' is only ever treated as a magic string).

[bblackham]

My proposed fix for the User.ip issue is here: bblackham/cms@a102720

[lw]

Seems good. I suggest to merge it after the release of v1.0, which should happen very soon.

Just a quick note: there's no UpdateDB script... not sure if we want one ;-)

[bblackham]

Yep, post definitely 1.0.

UpdateDB script would be trivial, but probably completely useless. (New contests wouldn't run with old IP locks). I don't think we should worry :)

[lw]

I'm putting this here, even if it's not strictly related: the DB allows Contest.start and .stop to be nullable, and assign to these values a meaning of -infinity and +infinity (respectively). I don't think that all of the code is aware of these cases...

[lw]

The current problems have been fixed in 483ee85, e051ee4 and d66951d. I keep this issue open to remember to look if I can find more...

[lw]

TODO: rename the table name of Testcases from "task_testcases" to "testcases".

[lw]

TODO: check that nobody is using Task.scorer and remove it.

[lw]

TODO: try to use a SmartMappedCollection for Contest.users and Contest.tasks (indexed by username and task name respectively).

[lw]

TODO: move Submission.LANGUAGES and Submission.LANGUAGES_MAP out of the DB classes since it has nothing to do with the DB... for example in cms/__init__.py.

[lw]

TODO: now that UpdateDB has been removed I think we don't need to give names to UniqueConstraints (and other constraints) anymore; we can remove them.

[lw]

TODO: use a proper many-to-many relationship for Task. and User.primary_statements. With the new ContestExporter/Importer it should be a piece of cake.

[lw]

@bblackham I was reading this discussion again and I'm not getting anymore the reason we don't need an UpdateDB script for the User.ip change (which, at this point, would be an UpdateDump script). Wouldn't it be useful to convert the '0.0.0.0' values into null? If we don't do that then reimported dumps won't work, right?