woocommerce-custom-variation-fields-functions-php

/**
 * Create new fields for variations
 *
*/
function variable_fields( $loop, $variation_data ) {
?>
    <tr>
        <td>
            <?php
            // Text Field
            woocommerce_wp_text_input(
                array(
                    'id'          => 'color_hex['.$loop.']',
                    'label'       => __( 'Swatch Color', 'woocommerce' ),
                    'placeholder' => '#ffffff',
                    'desc_tip'    => 'true',
                    'description' => __( 'Enter hex value of color to display when option is selected.', 'woocommerce' ),
                    'value'       => $variation_data['color_hex'][0]
                )
            );
            ?>
        </td>
    </tr>
<?php
}

/**
 * Create new fields for new variations
 *
*/
function variable_fields_js() {
?>
    <tr>
        <td>
            <?php
            // Text Field
            woocommerce_wp_text_input(
                array(
                    'id'          => 'color_hex[ + loop + ]',
                    'label'       => __( 'Swatch Color', 'woocommerce' ),
                    'placeholder' => '#ffffff',
                    'desc_tip'    => 'true',
                    'description' => __( 'Enter hex value of color to display when option is selected.', 'woocommerce' ),
                    'value'       => $variation_data['color_hex'][0]
                )
            );
            ?>
        </td>
    </tr>
<?php
}

/**
 * Save new fields for variations
 *
*/
function save_variable_fields( $post_id ) {
    if (isset( $_POST['variable_sku'] ) ) :

        $variable_sku          = $_POST['variable_sku'];
        $variable_post_id      = $_POST['variable_post_id'];

        // Text Field
        $color_hex = $_POST['color_hex'];
        for ( $i = 0; $i < sizeof( $variable_sku ); $i++ ) :
            $variation_id = (int) $variable_post_id[$i];
            if ( isset( $color_hex[$i] ) ) {
                update_post_meta( $variation_id, 'color_hex', stripslashes( $color_hex[$i] ) );
            }
        endfor;

    endif;
}