static array on functions.php

Question

In functions.php, I want to access the DB once to get an ACF object, and then "save" it locally to prevent further requests to the DB.

I thought of first calling the following function in the "init' hook.

Then, supposedly, when I call it on later hooks the $current_store var is already set because of the use of the "static" keyword, and the function will stop on the first "if" - returning the already saved static var.

It doesn't work - when accessing the function on later hooks 'isset($current_store)' returns false.

What am I doing wrong?

function get_current_store()
{
    if (isset($current_store)) {
        return $current_store;
    }

    $store_url_parts = explode('.', $_SERVER['HTTP_HOST']);
    $store_subdomain = $store_url_parts[0];

    $store_url_parts_reversed = array_reverse($store_url_parts);

    if (in_array("il", $store_url_parts_reversed)) {
        $domain = $store_url_parts_reversed[2];
    } else {
        $domain = $store_url_parts_reversed[2];
    }

    if ($store_subdomain == $domain) {
        $current_store = 'main';

        return $current_store;
    }

    if ($stores_page = get_page_by_title('Stores', OBJECT, 'option')) {
        $stores_page_id = $stores_page->ID;

        if (function_exists('have_rows')) {
            if (have_rows('stores', $stores_page_id)) {
                $store_url_parts = get_store_url_parts();
                $store_subdomain = $store_url_parts[0];
                $stores          = array();

                while (have_rows('stores', $stores_page_id)) {
                    the_row();

                $store = get_row(true);

                    $stores[] = $store;
                }

                $subdomains = array_column($stores, 'store_subdomain');

                $current_store_id     = array_search($store_subdomain, $subdomains);

                static $current_store = array();

                if ($current_store_id !== false) {
                    $current_store = $stores[$current_store_id];
                } else {
                    $current_store = false;
                }

                return $current_store;
            }
        }
   }

}

Answer 1

This is a good use case for the Object Cache:

WP_Object_Cache is WordPress' class for caching data which may be computationally expensive to regenerate, such as the result of complex database queries.

You can store things in the cache with wp_cache_set() and retrieve them with wp_cache_get(). You just need to give it a key and value, as well as a group name unique to your theme/plugin or set of functionality to avoid conflicts:

function get_current_store()
{
    // Check if the current store is cached.
    $cache = wp_cache_get( 'current_store', 'my_plugin' );

    // If it is, return the cached store.
    if ( $cache ) {
        return $cache;
    }

    // Otherwise do the work to figure out $current_store;

    // Then cache it.
    wp_cache_set( 'current_store', $current_store, 'my_plugin' );

    return $current_store;
}

Now no matter how many times you run get_current_store() on a page it will only do the work of generating the current store variable once.

Answer 2

Jacob Peattie answer is a great alternative.

But if someone iterested, the problem with my original code is that static $current_store needs to be declared at the beggining of the function.

This code works:

function get_current_store()
{
    static $current_store;

    if (isset($current_store)) {
        return $current_store;
    } else {
        $store_url_parts = explode('.', $_SERVER['HTTP_HOST']);
        $store_subdomain = $store_url_parts[0];

        $store_url_parts_reversed = array_reverse($store_url_parts);

        if (in_array("il", $store_url_parts_reversed)) {
            $domain = $store_url_parts_reversed[2];
        } else {
            $domain = $store_url_parts_reversed[2];
        }

        if ($store_subdomain == $domain) {
            $current_store = 'main';

            return $current_store;
        }

        if ($stores_page = get_page_by_title('Stores', OBJECT, 'option')) {
            $stores_page_id = $stores_page->ID;

            if (function_exists('have_rows')) {
                if (have_rows('stores', $stores_page_id)) {
                    $store_url_parts = get_store_url_parts();
                    $store_subdomain = $store_url_parts[0];
                    $stores          = array();

                    while (have_rows('stores', $stores_page_id)) {
                        the_row();

                        $store = get_row(true);

                        $stores[] = $store;
                    }

                    $subdomains = array_column($stores, 'store_subdomain');

                    $current_store_id = array_search($store_subdomain, $subdomains);

                    $current_store = array();

                    if ($current_store_id !== false) {
                        $current_store = $stores[$current_store_id];
                    } else {
                        $current_store = false;
                    }
                }
            }
            return $current_store;
        }
    }
}

Answer 3

if the $current_store is some kind of global variable then your function should start with

function get_current_store() {
    global $current_store
    // the rest of your source code here ...