How to flush rewrite rules on the activation of any plugin

Question

I created a function in functions.php that adds some rewrite rules:

function add_rewrite_rules() { 
    add_rewrite_rule('events/page/([0-9])*/?', 'index.php?pagename=events&paged=$matches[1]', 'top');
    [...]   
    global $wp_rewrite;
    $wp_rewrite->flush_rules();
}

I would like to execute it every time any plugin is activated, so if the new rules get overwritten I can restore them automatically. Is it possible?

Thank you.

Answer 1

1. Add your rewrite rules on the init action hook.

2. In your personal activation function, both a) add the rewrite rules and b) flush the rewrite rules. One time. This is the only time you need to flush the rules.

Alternatively, if your rewrite rules can change through user input, then you need to flush them when the rules change, not at any other time. You still need to add them on init though.

Answer 2

Hook your function on the init hook so it is always present-

function wpd_add_rewrite_rules() { 
    add_rewrite_rule('events/page/([0-9])*/?', 'index.php?pagename=events&paged=$matches[1]', 'top');
}
add_action( 'init', 'wpd_add_rewrite_rules' );

See the examples in Codex for flush_rewrite_rules for where to flush rules when you've added them, either in plugin activation or theme switch. Do not flush rewrite rules on init.

Answer 3

I wonder if this will work:

add_action( 'activated_plugin', function(){

    // your stuff here

}, PHP_INT_MAX );

where the hook activated_plugin is fired after a plugin is activated.