Handle updates

[eliemichel]

We are in developpment phase for now, but it would be very useful to handle updates such as change in database scheme in the public version.

I add this issue in order not to forget to do so, but it does not have to be implemented right now.

[Phyks]

For the implementation, I propose to add a version number somewhere (in the config for example), and to call a page update.php if the stored version number does not match the current one.

This page would contain update functions from versions to version. So:

• If we are in 0.1 and updated to 0.2, then, just call update_0.1_0.2.
• If we are in 0.1 and updated to 0.3, then call update_0.1_0.2 and then update_0.1_0.3.

The problem now is to define version numbers, and for now I'm not really willing to tag any version.

[Phyks]

An example is available in commit https://github.com/FreederTeam/Freeder/commit/baea8b1bf5e012e17426f5d31c063f6c0f50136a.

However, I did not test this update mechanism extensively, and this may be to improve.

[eliemichel]

Won't the number of functions be quadratic with this method? It may be easier to call update_0.1_0.2 and then update_0.2_0.3 since there are usually not a lot of versions of difference.

[Phyks]

Ok… I thought this but did not write it ><

Of course ! And I updated my last comment accordingly.