webme, step 2: upgrading and user accounts

Last time, we wrote a basic installer and nothing else. This time, we’ll create user/admin accounts and discuss how upgrading can be done easily.

With user accounts, it is tempting to create two separate tables of users – one of admins and another of ordinary users, but that’s redundant. The same information is saved in both cases, so it makes more sense to have one table dedicated to users as a whole and some way of distinguishing the ordinary users from the administrators.

The way we’ll handle this is through use of Roles. The simplest being to have a table of users and a table of groups, and if a user is a member of the “admins” groups, then they have admin privileges. This is an example of ACL, which can get very complex if you dig into it. I’d recommend sticking to just users and groups unless there is a really good reason to get more in-depth than that.

So, the next thing we need in the CMS is the ability to set up one admin from the installer, and the tables needed to support it.

Logging in will be done via email and password.

Up until recently, the most common method was logging in via username and password, but that has a disadvantage – when you forget your password, it’s also possible that you forgot which email address you registered with, or you no longer have access to the email address.

Using your email address as the login, you are reminded every time you login what email address the new password will be sent to if you forget the old one. And if you know you’ve lost access to the old email address, you can take measures to change the login email before it becomes impossible to do so.

Adapting the installer to ask for these details was not difficult so I won’t detail it.

Upgrades are an interesting problem.

In a non-database environment, upgrades consist of merely unzipping the new version over the old one (or running “svn up” in the root of the site).

Upgrades become much trickier when databases are involved. Upgrading the files might cause an inconsistency, where the scripts may reference database tables that don’t exist or have been changed.

One project I worked on got around this by having a directory which held database patch scripts which an upgrader should run before the site should be used again. That was messy.

Other projects get around this by requiring you to upgrade your files, and then go to a URL (/upgrade.php for example) which will do the database upgrade for you. Better, but still messy.

I think the solution is to have a database version number kept in a file which is upgraded (the front index.php for example), and another version number kept in the site config file, which is not upgraded. When someone visits the site index, it’s a non-expensive process to simply compare those numbers, and if they are different, then an upgrade is automatically performed, and the config file is adjusted with the new version number.

In that way, upgrading is simply a matter of unzipping the new files, and the next time anyone visits the site, it is upgraded automatically.

Anyway – that’s enough for this step. You still can’t create any pages, but we’re almost ready for it.

As usual, you can get this code from the google Webworks-Webme repository. No zipped package available yet, although the next article might be the first which warrants it (we’ll create an actual page and discuss templates).

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