Saving a product custom field and displaying it in cart page

Question

With WooCommerce and I am doing some customization in my functions.php file, to get a custom field value on Cart page.

I add a custom field before

Answer 1

There is a lot of errors and missing things in your code

1) SETTINGS:

If you want to display correctly the label "Name On T-Shirt" on customer Orders and email notifications, you need to create an attribute for this label name (under Products > Attributes):

Create a product attribute:

Add some value to this attribute:

and …

Then save…

2) The Code:

// Add the custom field to product pages
add_action( 'woocommerce_before_add_to_cart_button', 'add_nmy_custom_product_field', 10, 0 );
function add_nmy_custom_product_field() {
    ?>
        <table class="variations" cellspacing="0">
            <tbody>
                <tr>
                    <td class="label">
                        <label for="color"><?php _e('Name On T-Shirt', 'woocommerce'); ?></label>
                    </td>
                    <td class="value">
                        <input type="text" name="name-on-tshirt" value="" />
                    </td>
                </tr>
            </tbody>
        </table>
    <?php
}

// Save the custom product field data in Cart item
add_filter( 'woocommerce_add_cart_item_data', 'save_in_cart_my_custom_product_field', 10, 2 );
function save_in_cart_my_custom_product_field( $cart_item_data, $product_id ) {
    if( isset( $_POST['name-on-tshirt'] ) ) {
        $cart_item_data[ 'name-on-tshirt' ] = $_POST['name-on-tshirt'];

        // When add to cart action make an unique line item
        $cart_item_data['unique_key'] = md5( microtime().rand() );
        WC()->session->set( 'custom_data', $_POST['name-on-tshirt'] );
    }
    return $cart_item_data;
}

// Render the custom product field in cart and checkout
add_filter( 'woocommerce_get_item_data', 'render_custom_field_meta_on_cart_and_checkout', 10, 2 );
function render_custom_field_meta_on_cart_and_checkout( $cart_data, $cart_item ) {

    $custom_items = array();

    if( !empty( $cart_data ) )
        $custom_items = $cart_data;

    if( $custom_field_value = $cart_item['name-on-tshirt'] )
        $custom_items[] = array(
            'name'      => __( 'Name On T-Shirt', 'woocommerce' ),
            'value'     => $custom_field_value,
            'display'   => $custom_field_value,
        );

    return $custom_items;
}

// Add the the custom product field as item meta data in the order
add_action( 'woocommerce_add_order_item_meta', 'tshirt_order_meta_handler', 10, 3 );
function tshirt_order_meta_handler( $item_id, $cart_item, $cart_item_key ) {
    $custom_field_value = $cart_item['name-on-tshirt'];
    if( ! empty($custom_field_value) )
        wc_update_order_item_meta( $item_id, 'pa_name-on-tshirt', $custom_field_value );
}

This code goes in function.php file of your active child theme (or theme) or also in any plugin file.

This code works and is tested for WooCommerce version from 2.5 to 3.0+