Add a drop down to product edit pages in product d

Question

I am trying to figure out how to modify the singe product options so the product admin can pick from the drop down list the condition of product, i.e. new/ used.

Below is a code that allows product admin to enter the condition of product manually.

// Enabling and Displaying Fields in backend
add_action( 'woocommerce_product_options_general_product_data', 'woo_add_custom_general_fields' );
function woo_add_custom_general_fields() {
    global $woocommerce, $post;

    echo '<div class="options_group">';

    woocommerce_wp_text_input( array( // Text Field type
        'id'          => '_Stan', 
        'label'       => __( 'Stan', 'woocommerce' ), 
        'placeholder' => 'i.e: nowa; uzywana...',
        'desc_tip'    => 'true',
        'description' => __( 'Podaj stan plyty.', 'woocommerce' ) 
    ) );

    echo '</div>'; // Closing </div> tag HERE
}

// Save Fields values to database when submitted (Backend)
add_action( 'woocommerce_process_product_meta', 'woo_save_custom_general_fields' );
function woo_save_custom_general_fields( $post_id ){

    // Saving "Conditions" field key/value
    $Stan_field = $_POST['_Stan'];
    if( !empty( $Stan_field ) )
        update_post_meta( $post_id, '_Stan', esc_attr( $Stan_field ) );


}
add_action('woocommerce_single_product_summary', 'woo_display_custom_general_fields_values', 45);
function woo_display_custom_general_fields_values() {
    global $product;

    echo '<p class="custom-Stan">Stan: ' . get_post_meta( $product->id, '_Stan', true ) . '</p>';
}

Answer 1

There is some errors and mistakes so I have revisited a little bit your code. Now you will have to replace woocommerce_wp_text_input() by woocommerce_wp_select() to get a select field instead, this way:

// Enabling and Displaying Fields in backend
add_action( 'woocommerce_product_options_general_product_data', 'woo_add_custom_general_fields' );
function woo_add_custom_general_fields() {

    echo '<div class="options_group">';

    woocommerce_wp_select( array( // Text Field type
        'id'          => '_Stan',
        'label'       => __( 'Stan', 'woocommerce' ),
        'description' => __( 'Podaj stan plyty.', 'woocommerce' ),
        'desc_tip'    => true,
        'options'     => array(
            ''        => __( 'Select product condition', 'woocommerce' ),
            'Nowa'    => __('Nowa', 'woocommerce' ),
            'Uzywana' => __('Uzywana', 'woocommerce' ),
        )
    ) );

    echo '</div>';
}

// Save Fields values to database when submitted (Backend)
add_action( 'woocommerce_process_product_meta', 'woo_save_custom_general_fields', 30, 1 );
function woo_save_custom_general_fields( $post_id ){

    // Saving "Conditions" field key/value
    $posted_field_value = $_POST['_Stan'];
    if( ! empty( $posted_field_value ) )
        update_post_meta( $post_id, '_Stan', esc_attr( $posted_field_value ) );


}

// Display In front end
add_action( 'woocommerce_product_meta_start', 'woo_display_custom_general_fields_values', 50 );
function woo_display_custom_general_fields_values() {
    global $product;

    // compatibility with WC +3
    $product_id = method_exists( $product, 'get_id' ) ? $product->get_id() : $product->id;

    echo '<span class="stan">Stan: ' . get_post_meta( $product_id, '_Stan', true ) . '</span>';
}

Code goes in function.php file of the active child theme (or active theme).

Tested and works.

Is better to avoid capitals in meta keys and they should start with an underscore.