Woocommerce - Sort products in cart by Author/User in Multi-vendor setup

I have a multivendor Woocommerce shop using Dokan plugin and I'm trying to split out the shopping cart into sections based on who the vendor is. For example:

Vendor 1
- Product C
- Product B
Vendor 2
- Product A

Dokan uses a custom role 'vendor' to extend the user class, so to get the ID of the vendors, I should be able to use something like:

$post_data = get_post( $cart_item['product_id'] ); 
$vendor_id = $post_data->post_author;

This does work, but it will only get the first vendor ID and simply repeats that for all remaining products in the cart. I know this is because I'm not retrieving an array but I can't really find anything in the WP documentation on how to get an array of author IDs (other than wp_list_authors, but that doesn't work well).

As an experiment, I managed to get the splitting + sorting working so long as I'm sorting by categories, since I can use wp_get_post_terms(). I can't replicate this for author data, though...

Current (relevant) code is below:

<?php
$cat_sort = array();

foreach ( WC()->cart->get_cart() as $cart_item_key => $cart_item ) {
  $product_id = $cart_item['product_id'];
  $cat_ids = wp_get_post_terms( $product_id, 'product_cat', array( 'fields' => 'ids' ) );

  foreach ( $cat_ids as $id ) {
    $cat_sort[$id][$cart_item_key] = $cart_item;
  }                                                    

}

ksort( $cat_sort ); 

$grouped_cart_items = array();
  foreach ( $cat_sort as $cat_id => $cart_items ) {
    $term = get_term( $cat_id, 'product_cat' );                           
?>
<tr>
  <td colspan="6" class=""><strong><?php echo $term->name; ?></strong></td>
</tr>

(After this is the actual product loop which shouldn't be important here because their sort ordering happens in the above code)

Any ideas on how I can get author info for the cart products the same way I can get the categories? I'm pretty stumped...

Thanks in advance for any and all assistance!

Solution

Here is an example on how to sort and display cart items by Dokan vendor store name:

<table>
<?php

$car_items  = WC()->cart->get_cart(); // Cart items

$items_sort = array(); // Initializing

// Loop through cart items
foreach ( $car_items as $cart_item_key => $cart_item ) {
    // Get the vendor_id
    $vendor_id   = get_post_field( 'post_author', $cart_item['product_id'] );

    $store_info  = dokan_get_store_info( $vendor_id ); // Get the store data
    $store_name  = $store_info['store_name'];          // Get the store name

    // Set in multidimentional array the vendor and then the cart item key
    $items_sort[$store_name][$cart_item_key] = $vendor_id;
}

if ( count($car_items) > 1 ) {
    ksort( $items_sort ); // Sorting by vendor name
}

// 1st Loop by vendor name
foreach ( $items_sort as $store_name => $values ) {
    $vendor_id  = reset($values); // The vendor id
    /$store_url = dokan_get_store_url( $vendor_id );  // Get the store URL (if needed)
    ?>
    <tr>
        <!-- Store name display -->
        <td colspan="6" class="store-name"><strong><?php echo $store_name; ?></strong></td>
    </tr>
    <?php
    // 2nd Loop the cart items for the vendor name
    foreach( $values as $cart_item_key => $vendor_id) {

        // Retreive the cart item from the cart item key
        $cart_item = $car_items[$cart_item_key];
        ?>
        <tr>
            <!-- Product name display -->
            <td colspan="6" class="product-name"><?php echo $cart_item['data']->get_name(); ?></td>
        </tr>
        <?php

    } // End of 2nd Loop

} // End of 1st Loop

?>
</table>