Get post meta during checkout

How do a get post meta in Woocommerce? I added a custom field to a product with this code:

// Display Fields
add_action( ‘woocommerce_product_options_general_product_data’, ‘woo_add_custom_general_fields’ );

// Save Fields
add_action( ‘woocommerce_process_product_meta’, ‘woo_add_custom_general_fields_save’ );

function woo_add_custom_general_fields() {

global $woocommerce, $post;

echo ‘<div class=”options_group”>’;

// Text Field
woocommerce_wp_text_input(
array(
‘id’ => ‘_text_field’,
‘label’ => __( ‘Custom field name here’, ‘woocommerce’ ),
‘placeholder’ => ‘Vul hier je id in’,
‘desc_tip’ => ‘true’,
‘description’ => __( ‘Vul hier je id in.’, ‘woocommerce’ )
)
);

echo ‘</div>’;

}

// Save fields //
function woo_add_custom_general_fields_save( $post_id ){

// Text Field
$woocommerce_text_field = $_POST[‘_text_field’];
if( !empty( $woocommerce_text_field ) )
update_post_meta( $post_id, ‘_text_field’, esc_attr( $woocommerce_text_field ) );
}

And try to get this with:

// Get the product ID
$product_id = get_post_meta( get_the_ID(), ‘_text_field’, true);

But when i try to run a checkout it sticks at the checkout screen. I tried it with hardcoded the value of _text_field and this works, but how to make it dynamic?

Thanks!

– Menno

https://wordpress.org/plugins/woocommerce/