How to get the current session array count in twig?

问题

In my bootstrap file where I instantiate my twig I have:

$twig->addGlobal('cart', $session->get('cart'));

and in top navbar of my twig I have a badge to show how many items are in added in cart as below:

{{ cart|length }}

and my main file that is called after bootstrap file I said above, I have:

if (!empty($_getvars['id'])) {
    $data = $session->get('cart');
    if(!isset($data[$_getvars['id']])) {
        $data[$_getvars['id']] = 0;
    }
    $data[$_getvars['id']] += 1;
    $session->set('cart', $data);
} 
print_r($session->get('cart'));

adding to sessions is working fine, and print debug above shows that it is accurate, but in the top navbar badge I always get the previous amount of items rather than current amount unless otherwise I refresh the page to show the current. How to fix it?

回答1:

Instead of setting global twig var, read directly from the session in the template like so:

{% set cart = app.session.get('cart') %}
{{ cart|length }}

Or simply:

{{ app.session.get('cart')|length }}

This should give you the updated value (after the controller action has processed the data).

However, looking at your related questions, I think you want array_sum() instead of length, in twig you can use the reduce filter:

{{ app.session.get('cart')|reduce((carry, v) => carry + v) }}

This will sum all of the quantity values in the cart array (total quantity of items vs. number of unique items with length)

EDIT:
For a stand-alone app, as mentioned by DarkBee, you could just add the session object as global instead of the session cart value.

$twig->addGlobal('session', $session);

Then in the template:

{{ session.get('cart')|length }}
{# Or #}
{{ session.get('cart')|reduce((carry, v) => carry + v)}}

来源：https://stackoverflow.com/questions/58528052/how-to-get-the-current-session-array-count-in-twig