Should WordPress plugins that make any database schema changes have a local database scheme version number?
The plugin README file has tags for Requires at least, Tested up to and Stable tag.
I’m suggesting that alongside defining the plugin version, and the three README tags, there should be a value for the schema. This means that plugin authors can explicitly note when their plugin is updating the schema.
Whether it goes in the main plugin file next to plugin version, or in the README file I’m not sure it makes any difference. But if we build in some hooks to trigger on schema version change then we gain two things. Firstly, developers like it as they can explicitly perform tasks based on schema versions and version changes. And secondly, users can be notified that the plugin is about to make schema changes. Which might encourage backups.
I think that’s a win-win!
Having been playing around with WordPress Network (Multisite) plugins, mostly internal, not doing much that anyone else would be interested in having. During a plugin’s lifetime it goes through some critical points. The one you can’t avoid is activation. Many also experience deactivation or even deletion. Most will, at some point, be updated. for these critical points the plugin author may want to have certain critical events happen. Setting up options, creating databases, pre-populating meta data. And of course the reverse – deleting said litter.
A quick summary of the register_activation_hook() function:
- It doesn’t work on multisite. Network activation does not trigger this function
- Updating the plugin does not trigger it
- It is triggered every time a plugin is manually re-activated
None of these are my desired behaviour. I usually write my own hook that checks if the plugin version has changed, and fire off my actions.
Which makes me wonder whether the function is out dated, and should be replaced a set of alternative functions. They could perhaps even be actions?