Restrict content to those who purchased a Woocommerce product

I’m trying to restrict content on the page via shortcode for those who purchased a particular woocommerce product. I tried using the code below but it’s not working – shortcode [wcr pid="78] this is some text [/wcr] is just being outputted on the page without hiding the content. Woocommerce has a function for restricting content like this.

/**
 * [wcr_shortcode description]
 * @param  array  pid    product id from short code
 * @return content          shortcode content if user bought product
 */
function wcr_shortcode($atts = [], $content = null, $tag = '')
{
    // normalize attribute keys, lowercase
    $atts = array_change_key_case((array) $atts, CASE_LOWER);

    // start output
    $o = '';

    // start box
    $o .= '<div class="wcr-box">';

    $current_user = wp_get_current_user();

    if ( current_user_can('administrator') || wc_customer_bought_product($current_user->email, $current_user->ID, $atts['pid'])) {
        // enclosing tags
        if (!is_null($content)) {
            // secure output by executing the_content filter hook on $content
            $o .= apply_filters('the_content', $content);
        }

    } else {
        // User didn't buy product and not an administator
    }
    // end box
    $o .= '</div>';

    // return output
    return $o;
}

Answer

There is some mistakes in your code and in the way to use the shortcode too

1) The code:

add_shortcode( 'wcr', 'wcr_shortcode' );
function wcr_shortcode( $atts, $content = null ){
    // Normalize attribute keys, lowercase
    $atts = array_change_key_case( (array) $atts, CASE_LOWER );

    // Shortcode Attributes
    $atts = shortcode_atts( array(
        'pid'   => ''
    ), $atts, 'wcr' );

    $user = wp_get_current_user();

    // start output
    $html = '<div class="wcr-box">';

    if ( current_user_can('administrator') || wc_customer_bought_product( $user->email, $user->ID, $atts['pid'] ) ) {
        // enclosing tags
        if ( ! is_null($content) ) {
            // secure output by executing the_content filter hook on $content
            $html .= apply_filters( 'the_content', $content );
        }

    } else {
        // User hasn't bought this product or is not an administrator
        $html .= __("Please purchase the product first to see the content", "woocommerce");
    }
    // end box
    $html .= '</div>';

    // return output
    return $html;
}

2) the shortcode usage:

• In a text editor: [wcr pid="78"] this is some text [/wcr].
• Inside php code: echo do_shortcode( '[wcr pid="78"] this is some text [/wcr]' );.

Code goes in functions.php file of your active child theme (active active theme). Tested and works.