WP_Filesystem in custom customize control

Question

I'm currently trying to edit the following file so it uses the WP_Filesystem methods instead of direct PHP filesystem calls: google-font-dropdown-custom-control.php

My current code looks as follows:

function mytheme_customize_register( $wp_customize ) {

    $wp_customize->add_section('fonts', array(
        'title' => 'Font',
        'priority' => 40
        ));

    $wp_customize->add_setting( 'google_webfont' , array(
        'default'     => 'Open Sans',
        'transport'   => 'refresh',
    ) );


    if (false === ($creds = request_filesystem_credentials('customize.php', '', false) ) ) {

        // if we get here, then we don't have credentials yet,
        // but have just produced a form for the user to fill in, 
        // so stop processing for now

        return true; // stop the normal page form from displaying
    }

    // now we have some credentials, try to get the wp_filesystem running
    if ( ! WP_Filesystem($creds) ) {
        // our credentials were no good, ask the user for them again
        request_filesystem_credentials('customize.php', '', true);
        return true;
    }

    global $wp_filesystem;
    require_once('inc/google-font-dropdown-custom-control.php');

    $wp_customize->add_control( new Google_Font_Dropdown_Custom_Control( $wp_customize, $wp_filesystem, 'google_font_setting', array(
        'label'   => 'Title Font',
        'section' => 'fonts',
        'settings'   => 'google_webfont'
    ) ) );


}
add_action( 'customize_register', 'mytheme_customize_register' );

This however throws me the following error:

Call to undefined function request_filesystem_credentials()

It seems like you can't use the Filesystem in the Theme Customizer? What would the solution be, any tips?

Answer 1

To cache something you can use the Transients API (thanks @Otto), get_transient() to see if it exists already exists, if not then fetch the data and store it in a transient with set_transient().

    if (get_transient('mytheme_webfonts')) {
        $content = get_transient('mytheme_webfonts');
    }
    else{
        $googleApi = 'https://www.googleapis.com/webfonts/v1/webfonts?sort=alpha&key={API_KEY}';

        $fontContent = wp_remote_get( $googleApi, array('sslverify'   => false) );

        $content = json_decode($fontContent['body']);

        set_transient( 'mytheme_webfonts', $content, WEEK_IN_SECONDS );
    }