Tukukkk

I am creating products that vary greatly in size and weight. I am not using WooCommerce product variants to help me with this as my products are heavily customized. I am using a third-party plugin to select from many variant options and I plan on checking these options to determine the products weight.

The issue is I want to set the product weight before the product is added to the cart. A shipping calculator on the cart will then calculate your shipping based off your cart's total weight (WooCommerce Weight Based Shipping).

I have tried 2 WooCommerce hooks pretty extensively to do this with no luck.

add_filter( 'woocommerce_add_cart_item_data', 'update_weight_on_add_to_cart', 10, 3);

and

add_action( 'woocommerce_add_to_cart', 'update_weight_on_add_to_cart', 10, 6 );

I am able to set custom fields using the add_filter. Doing this I am able to see that I successfully set the product weight to something new. BUT once I get to the cart page, the weight is reverted back to what is set on the edit product page.

This is the function I am currently using to check that:

function update_weight_on_add_to_cart( $cart_item_data, $product_id, $variation_id )

{

    $product = wc_get_product( $product_id );



    $weight1 = $product->get_weight();



    $product->set_weight(3.45);

    $weight2 = $product->get_weight();



    $cart_item_data['weight1'] = $weight1;

    $cart_item_data['weight2'] = $weight2;



    return $cart_item_data;

}

Then I display these fields on the cart to see if I changed the data successfully using the following hook and function. (I grabbed most of this from blog posts or other StackOverflow posts)

add_filter( 'woocommerce_get_item_data', 'display_weight', 10, 2 );

function display_weight( $item_data, $cart_item ) {

    $item_id = $cart_item['variation_id'];

    if($item_id == 0) $item_id = $cart_item['product_id'];

    $product_qty = $cart_item['quantity'];

    $product = wc_get_product($item_id);

    $weight3 = $product->get_weight();



    $item_data = array(

        'key'       => __('Weight3', 'woocommerce'),

        'value'     => wc_clean( $weight3 ),

        'display'   => ''

    );

     $item_data = array(

        'key'     => __( 'Weight1', 'woocommerce' ),

        'value'   => wc_clean( $cart_item['weight1'] ),

        'display' => ''

    );

     $item_data = array(

        'key'     => __( 'Weight2', 'woocommerce' ),

        'value'   => wc_clean( $cart_item['weight2'] ),

        'display' => ''

    );



    return $item_data;

}

My most recent effort using the above code resulted in the following on the cart page.

Weight3: 1

Weight1: 1

Weight2: 3.45

Any help would be appreciated! If this can't be done this way, is there a better way to approach this issue? Maybe this needs to be done on the cart?

There is some errors, mistakes and missing part… Here it's the way to do it (for all products types including product variations):

// make and save a calculated weight as custom cart item data

add_filter( 'woocommerce_add_cart_item_data', 'add_weight_custom_cart_item_data', 10, 3 );

function add_weight_custom_cart_item_data( $cart_item_data, $product_id, $variation_id ){

    // For product variations handling

    $product_id = $variation_id > 0 ? $variation_id : $product_id;



    // Get an instance of the product object

    $product = wc_get_product( $product_id );



    // The default product weight

    $cart_item_data['weight']['default'] = $product->get_weight();



    ## ====> HERE YOU CAN MAKE YOUR WEIGHT CALCULATIONS <==== ##

    $new_weight_value = 3.45;



    // Set the new calculated weight

    $cart_item_data['weight']['new'] = 3.45;



    return $cart_item_data;

}



add_filter( 'woocommerce_get_item_data', 'display_cart_item_weight', 10, 2 );

function display_cart_item_weight( $item_data, $cart_item ) {

    if ( isset($cart_item['weight']) ) {

        // Display original weight

        if ( isset($cart_item['weight']['default']) ) {

            $item_data = array(

                'key'       => __('Weight (original)', 'woocommerce'),

                'value'     => wc_format_weight( $cart_item['weight']['default'] ),

            );

        }



        // Display calculated weight

        if ( isset($cart_item['weight']['new']) ) {

            $item_data = array(

                'key'     => __( 'Weight (new)', 'woocommerce' ),

                'value'   => wc_format_weight( $cart_item['weight']['new'] ),

            );

        }

    }

    return $item_data;

}



// Set the new weight in cart items

add_action( 'woocommerce_before_calculate_totals', 'set_custom_cart_item_weight', 25, 1 );

function set_custom_cart_item_weight( $cart ) {

    if ( is_admin() && ! defined( 'DOING_AJAX' ) )

        return;



    if ( did_action( 'woocommerce_before_calculate_totals' ) >= 2 )

        return;



    foreach( $cart->get_cart() as $cart_item ){

        if ( isset($cart_item['weight']['new']) ) {

            $cart_item['data']->set_weight($cart_item['weight']['new']);

        }

    }

}

Code goes in function.php file of your active child theme (active theme). Tested and works.