How to get the number of items in a user's cart from commerce?

Question

I've been looking into the drupal 8 commerce module, I want to take the variable $count that is generated within

../commerce/modules/cart/src/plugin/block/CartBlock.php

and place it into a custom block in my own theme. I see that the build() function returns the count variable through #count which can then be accessed via twig. Just for reference Drupal commerce currently uses the template:

../commerce/modules/cart/templates/commerce-cart-block.html.twig

to output the variables and markup:

<div{{ attributes}}>
  <div class="cart-block--summary">
    <a class="cart-block--link__expand" href="{{ url }}">
      <span class="cart-block--summary__icon">{{ icon }}</span>
      <span class="cart-block--summary__count">{{ count_text }}</span>
    </a>
  </div>
  {% if content %}
  <div class="cart-block--contents">
    <div class="cart-block--contents__inner">
      <div class="cart-block--contents__items">
        {{ content }}
      </div>
      <div class="cart-block--contents__links">
        {{ links }}
      </div>
    </div>
  </div>
  {% endif %}
</div>

My question is, how I can I make that variable global, are there any implications to just making it global, like what if the user updates the basket?

How do I go about achieving this? Does anyone have a possible solution?

Answer 1

you will have to use hook_preprocess_hook to achieve this by passing the variable to the template.

function template_preprocess_TEMPLATE_NAME(&$variables) {
    $variables['YOUR_VAR_NAME'] = $YOUR_VAR;
}

Then you can access your var in the template like so:

{{ YOUR_VAR_NAME }}