Changing shipping methods depending on products in cart

Question

I want to change shipping method depending on products present in the cart.
There are different weights assigned to products.
If all products present in the cart are of less than 5 k.g (weight for each product) then one shipping method will display.

If any one product in the cart, has weight greater than 5 kg. then show another shipping method.

Answer 1

You need to rewrite the collectRates method from the 2 methods you need and add this.
for the one that is allowed only if all the products are below 5kg:

$items = $request->getAllItems();
foreach ($items as $item) {
    if ($item->getProduct()->getWeight() > 5) {
         return false;
    }
}

and for the one that is allowed only if there is a product with weight over 5:

$items = $request->getAllItems();
$allowed = false;
foreach ($items as $item) {
    if ($item->getProduct()->getWeight() > 5) {
         $allowed = true;
         break;
    }
}
if (!$allowed) {
     return false;
}