How does one flush rules on theme activation or deactivation only?

Question

Flushing rules is clearly an important part of creating themes with custom post types. See here and here.

Does anyone have any example code of how to flush rules from functions.php?

I'm a little surprised this isn't covered in the custom post type pages of the Codex.

Update: I tried adding this to functions.php, but it didn't work:

register_deactivation_hook( __FILE__, array(&$this,'deactivate' ) );
function deactivate() {
 global $wp_rewrite;
 $wp_rewrite->flush_rules();
}

Answer 1

While the solutions provided here do still work, WordPress has evolved since and does now (since 3.3, I believe) provide direct hooks for theme activation.

after_switch_theme will fire on theme activation and switch_theme before deactivating an old theme.

Hence the up-to-date answer is:

function reflush_rules() {
    global $wp_rewrite;
    $wp_rewrite->flush_rules();
}
add_action( 'after_switch_theme', 'reflush_rules' );

Answer 2

this code (taken from Ozh's comment here with small addition) may help you.

function reflush_rules() {
  if ( is_admin() && isset($_GET['activated'] ) && $pagenow == "themes.php" ) {
    global $wp_rewrite;
    $wp_rewrite->flush_rules();
  }
}
add_action('init', 'reflush_rules');

edit:

add this function on your functions.php. This function will only loaded when theme activated (the only time $_GET['activated'] is set).

Answer 3

Not sure about flushing on deactivation, but activation is pretty easy.

In your functions.php file, set up some code like the following:

function flush_rules_on_activation() {  
    global $wp_rewrite;
    $is_installed = get_option('theme_installed');
    if(!$is_installed) {
        $wp_rewrite->flush_rules();
        add_option('theme_installed', true);
    }
}
add_action('init', 'flush_rules_on_activation');

This will run every time, but the rules will only be flushed once because you set a flag in your options table to prevent flushing them every time.

Answer 4

I had to modify bangbambang's answer to get this to work.

The code should be:

add_action('init', 'reflush_rules');
function reflush_rules() {
$pagenow = $_SERVER['SCRIPT_NAME'];
if ( is_admin() && isset($_GET['activated'] ) && $pagenow == "/wp-admin/themes.php" ) {
    global $wp_rewrite;
    $wp_rewrite->flush_rules();
}
}

Answer 5

What actually seem to work is adding this line after register_post_type:

flush_rewrite_rules( false );