Craft Commerce: Filter completed orders based on a product category field

Question

I know how to filter entries or products based on a category field with .relatedTo, but how can I filter completed orders based on a product category field?

In this specific case, I have an overview of completed orders. I would like to select a category and show only those orders that contain products with the selected category.

Any hints in the right direction are greatly appreciated!

Answer 1

Managed to solve this.

First, I've added a categories field to the order form.

On the checkout page I loop over all lineItems in the cart and collect the category id's like this.

{% set categoryIds = [] %}

{% for item in cart.lineItems %}
  {% set categories = item.purchasable.product.productGroup.leaves().all()%}
  {% for category in categories %}
    {% if category.id not in categoryIds %}
      {% set categoryIds = categoryIds|merge([category.id]) %}
    {% endif %}
  {% endfor %}
{% endfor %}

Then, I submit the categories using a hidden input.

{% for catId in categoryIds %}
  <input type="hidden" name="fields[productGroup][]" value="{{ catId }}">
{% endfor %}

Now I have categories assigned to an order and can easily filter them using .relatedTo(), like this:

{% set ordersQuery = craft.orders().relatedTo(...) %}