how can a plugin return an error message on activation?

Question

I'm developing a plugin that needs a certain php extension (sqlite3) to be available, or it can't work correctly.

Is there a way I can present an error message to the site owner when they try to activate it, saying something like this?

Sorry, you can't use this. Because yadda yadda. Click here for more information.

It doesn't look like there's a way for an activation hook to do anything except throw an error or generated "unexpected output". Am I missing something?

Is there a good way to refuse plugin activation from the activation hook?

Answer 1

I use code similar to this to check for the minimum requirements for a plugin:

if (is_admin()) {
// check for required versions of WP and PHP
    $min_wp  = '4.9.6';
    $min_php = '7.2';
    if (!check_requirements($min_wp, $min_php)) {
        add_action('admin_init', 'my_disable_plugin');
        add_action('admin_notices', 'my_show_notice_disabled_plugin');
        add_action('network_admin_init', 'my_disable_plugin');
        add_action('network_admin_notices', 'my_show_notice_disabled_plugin');
        my_deregister();
        return;
    }
}
function check_requirements($min_wp, $min_php) {
   // see this for how to check requirements https://www.sitepoint.com/preventing-wordpress-plugin-incompatibilities/ 
   // set $requirements_met true if OK, false if not OK
return $requirements_met;
}

function my_disable_plugin() {
   // disable the plugin 
}
function my_show_notice_diabled_plugin() {
   // admin notice that plugin disabled
}
function my_deregister() {
   // de-register the plugin
}

So if on the admin page, the plugin minimum requirements are checked. If that fails, the plugin is disabled and de-registered, and the admin notices displayed with the alert.