Run a function only once – share variable across templates PHP

Store the variable as a theme option in the wp_options table?

Aah, but I cannot store the variable in the database, sorry I forgot to point that out.

Why not (curious minds and all that…)?

I can as well call the API again and again. I can store the variable in the database, then for every product, I would have to make extra database calls for the variable. Plus, since the value of variable changes every second, it could and should be different for different customers, I should refrain from using the normalised value of the variable. Is there any other way ? ??

Not really – especially if storing the variable in a session isn’t working for you.

You could always try something like this (not tested, so coudl have bugs)…

$api_value = NULL;

function get_api_value () {
    global $api_value;

    if (is_null ($api_value)) {
        $api_value = call_api ();
    }

    return $api_value;
}

That will allow you to get the value once per page execution and share it as many times as needed.

Esmi : I tried storing the variable in session, but on every page, value in the session variable changed, could you point me how to store it in a session properly ?

Catacaustic : Thanks for replying. I agree, I can use something like that to load a variable value once per page execution, but what I am looking for is something where I can store it for the entire time the user is on the website(session). Since, I don’t exactly know when the session gets over, it should have a timeout too. Lastly, I might even try storing the value in user’s cookie. If you have any idea in either direction or another idea, please point me towards it ??

Either use a cookie, or wordpress transient.

function get_api_value() {
    if ( false === ( $value = get_transient( 'api_value' ) ) ) {
        $value = call_api();
        set_transient( 'api_value', $value, 3600 ); // store for 3600s
    }
    return $value;
}

https://codex.www.ads-software.com/Transients_API

Yes, awesome, this works great. To test it out, I did the following :

function get_rand_value() {
    if ( false === ( $value = get_transient( 'api_value' ) ) ) {
        $value = rand(0,10);
        set_transient( 'api_value', $value, 3600 ); // store for 3600s
    }
    return $value;
}

And I called get_rand_value() in footer, so that it gets called on every template. Works great man, thanks. I would still like to learn if it is possible to put it in session, just for learning sake. ??

Sessions are a bit overkill, and if the server isnt setup write, session_save_path etc they can be a pain as well.
Cookies or transients, thats my vote ??

Yup, and its working great. ??