Woocommerce: Users able to buy a product only once

Question

What can I add to the functions.php file of my theme that would make it so that users could only buy a product once? As in if they have ever bought any product in the store before, they are prevented from purchasing it again.

I imagine the code would look something like this (pseudo code) and would use the woocommerce_add_cart_item_data filter.

add_filter( 'woocommerce_add_cart_item_data', 'woo_check_not_bought_before' );

function woo_check_not_bought_before( $cart_item_data ) {

    global $woocommerce;

    // Some MYSQL to check if product was bought before

    if ($bought_before == 'true') {       
         $woocommerce->cart->empty_cart();
    }

    // Echo some text to explain why you can only buy the product once

    return $cart_item_data;
}

Answer 1

You might use this code to achieve your requirement. Create a folder called woocommerce in your theme. Then create a folder named loop in it. Then create a add-to-cart.php file in it and write the below code:

  if ( ! defined( 'ABSPATH' ) ) exit; // Exit if accessed directly

  global $product;
  $current_user = wp_get_current_user();

 if ( wc_customer_bought_product( $current_user->user_email, $current_user->ID, $product->id)) {
    echo 'Purchased';
    }
   else
   {
   echo apply_filters( 'woocommerce_loop_add_to_cart_link',
  sprintf( '<a href="%s" rel="nofollow" data-product_id="%s" data-product_sku="%s" class="button          %s product_type_%s">%s</a>',
    esc_url( $product->add_to_cart_url() ),
    esc_attr( $product->id ),
    esc_attr( $product->get_sku() ),
    $product->is_purchasable() ? 'add_to_cart_button' : '',
    esc_attr( $product->product_type ),
    esc_html( $product->add_to_cart_text() )
),
$product );
  } 

But the user can still make a different account and buy that product again.

Answer 2

here's a simple solution.

add_filter('woocommerce_add_to_cart_validation','rei_woocommerce_add_to_cart_validation',20, 2);
function rei_woocommerce_add_to_cart_validation($valid, $product_id){
    $current_user = wp_get_current_user();
    if ( wc_customer_bought_product( $current_user->user_email, $current_user->ID, $product_id)) {
        wc_add_notice( __( 'Purchased', 'woocommerce' ), 'error' );
        $valid = false;
    }
    return $valid;
}

screenshot

problem with this though is that anyone can create a new user and buy again.

Answer 3

Adding onto WisdmLabs's answer, you will also need to edit the shortcodes and other instances of the add to cart button.

To do this, create another folder: /wp-content/themes/[theme]/woocommerce/single-product/add-to-cart/

Create a file in that folder: simple.php and add the following code:

<?php
/**
 * Simple product add to cart
 *
 * @author      WooThemes
 * @package     WooCommerce/Templates
 * @version     2.1.0
 */

if ( ! defined( 'ABSPATH' ) ) {
    exit; // Exit if accessed directly
}

global $product;

if ( ! $product->is_purchasable() ) {
    return;
}

?>

<?php
    // Availability
    $availability      = $product->get_availability();
    $availability_html = empty( $availability['availability'] ) ? '' : '<p class="stock ' . esc_attr( $availability['class'] ) . '">' . esc_html( $availability['availability'] ) . '</p>';

    echo apply_filters( 'woocommerce_stock_html', $availability_html, $availability['availability'], $product );
?>

<?php if ( $product->is_in_stock() ) : ?>

    <?php do_action( 'woocommerce_before_add_to_cart_form' ); ?>

    <form class="cart" method="post" enctype='multipart/form-data'>
        <?php do_action( 'woocommerce_before_add_to_cart_button' ); ?>

        <?php
            if ( ! $product->is_sold_individually() ) {
                woocommerce_quantity_input( array(
                    'min_value'   => apply_filters( 'woocommerce_quantity_input_min', 1, $product ),
                    'max_value'   => apply_filters( 'woocommerce_quantity_input_max', $product->backorders_allowed() ? '' : $product->get_stock_quantity(), $product ),
                    'input_value' => ( isset( $_POST['quantity'] ) ? wc_stock_amount( $_POST['quantity'] ) : 1 )
                ) );
            }
        ?>

        <input type="hidden" name="add-to-cart" value="<?php echo esc_attr( $product->id ); ?>" />
        <?php $current_user = wp_get_current_user();

        if ( wc_customer_bought_product( $current_user->user_email, $current_user->ID, $product->id)) { echo '<span class="product-purchased">Purchased</span>';}
        else { ?><button type="submit" class="single_add_to_cart_button button alt"><?php echo esc_html( $product->single_add_to_cart_text() ); ?></button><?php }?>

        <?php do_action( 'woocommerce_after_add_to_cart_button' ); ?>
    </form>

    <?php do_action( 'woocommerce_after_add_to_cart_form' ); ?>

<?php endif; ?>

You will then also be able to edit the "Purchased" text using css class: product-purchased.

Separate files needs to be added with different code for external.php, grouped.php, variable.php if you want this functionality to work for those product types as well.