Validate e-mail address based on previous orders before adding product to cart in WooCommerce

Question

I have added a custom text-field on the single product page with the "PPOM for WooCommerce" plugin

The intention here is that the user enters his e-mail address and then clicks on the "add-to-cart" button

But before adding the product to his card, I want to check on the basis of the e-mail address whether this already occurs in the existing orders

I already found out about using a filter like woocommerce_add_to_cart_validation to accomplish what I want to do but to be honest, that is how far I got

function validate_email( $passed, $product_id, $quantity, $variation_id = '', $variations= '' ) {
    // TODO: Collect all previous orders using the entered email address and check if this already exists in the DB

    wc_add_notice( __( 'E-Mail Address already sold', 'woocommerce' ), 'error' );
    return false;
}
add_filter( 'woocommerce_add_to_cart_validation', 'validate_email', 10, 5 );

---

It would be great if anyone could give me some guidance on how to accomplish that

Answer 1

• I don't use the (paid) plugin that you use, so in my answer, I add a field via custom code to the single product page
• After entering an email address, some validation will take place (not empty, valid email), this can be further expanded to your needs
• If the email address is valid, all previous orders with that email address will be read from the database
  • wc_get_orders() is used for this, this can be further expanded with additional parameters such as certain order statuses, etc.
• If the product ID you want to add to the shopping cart is present in previous orders (with customer email), an error message will be displayed.

So you get:

// Add input field to single product page
function action_woocommerce_before_add_to_cart_button() {
    echo '<div class="custom-field-wrapper">';
    echo '<label for="customer-email">Enter your email:</label>';
    echo '<input type="email" id="customer-email" name="customer-email">';
    echo '</div>';
}
add_action( 'woocommerce_before_add_to_cart_button', 'action_woocommerce_before_add_to_cart_button', 10, 0 );

// Validate
function filter_woocommerce_add_to_cart_validation( $passed, $product_id, $quantity, $variation_id = null, $variations = null ) {
    // Isset
    if ( isset ( $_POST['customer-email'] ) ) {
        // Sanitize
        $customer_email = sanitize_text_field( $_POST['customer-email'] );
        
        // Empty
        if ( empty ( $customer_email ) ) {
            wc_add_notice( __( 'Please enter a value into the field', 'woocommerce' ), 'error' );
            $passed = false;
            
        // Verifies that an email is valid.
        // NOT valid
        } elseif ( ! is_email( $customer_email ) ) {
            wc_add_notice( __( 'Invalid email address', 'woocommerce' ), 'error' );
            $passed = false;
        } else {
            // Get orders by email
            $orders_by_customer_email = wc_get_orders( array(
                'customer' => $customer_email,
            ));
            
            // Set flag
            $flag = false;
            
            // This function is an alias of count()
            if ( sizeof( $orders_by_customer_email ) > 0 ) {
                // Iterating through each order
                foreach ( $orders_by_customer_email as $order ) {
                    // Going through order items
                    foreach ( $order->get_items() as $item ) {
                        // Get product ID
                        $product_id_in_order = $item->get_variation_id() > 0 ? $item->get_variation_id() : $item->get_product_id();
                    
                        // Compare
                        if ( $product_id_in_order == $product_id ) {
                            $flag = true;
                            break;
                        }
                    }
                }
            }
            
            // True
            if ( $flag ) {
                wc_add_notice( __( 'You have already purchased this product before', 'woocommerce' ), 'error' );
                $passed = false;
            }
        }
    }
    
    return $passed;
}
add_filter( 'woocommerce_add_to_cart_validation', 'filter_woocommerce_add_to_cart_validation', 10, 5 );

---

Note: if it is not specifically about the current product ID, but about all previously sold items

Replace this part

// This function is an alias of count()
if ( sizeof( $orders_by_customer_email ) > 0 ) {
    // Iterating through each order
    foreach ( $orders_by_customer_email as $order ) {
        // Going through order items
        foreach ( $order->get_items() as $item ) {
            // Get product ID
            $product_id_in_order = $item->get_variation_id() > 0 ? $item->get_variation_id() : $item->get_product_id();
        
            // Compare
            if ( $product_id_in_order == $product_id ) {
                $flag = true;
                break;
            }
        }
    }
}

// True
if ( $flag ) {
    wc_add_notice( __( 'You have already purchased this product before', 'woocommerce' ), 'error' );
    $passed = false;
}

With

// This function is an alias of count()
if ( sizeof( $orders_by_customer_email ) > 0 ) {
    $flag = true;
}

// True
if ( $flag ) {
    wc_add_notice( __( 'You have already purchased something before', 'woocommerce' ), 'error' );
    $passed = false;
}