List child categories which have entries based on the current categories

Question

I am looking to output the child categories of a parent category. I only need to show the categories which have entries related to them.

I have done this to show all categories using

{% set entryIds = craft.entries.section('stories').ids() %}
{% set categories = craft.categories.relatedTo({ sourceElement: entryIds }).groupId(2).orderBy('title').all() %}

What is the best way to do this for subcategories.

Answer 1

Use the descendantOf parameter to select just the subcategories, then run an entries query to check if that category has any entries assigned to it.

<ul>
    {# loop through the subcategories #}
    {% for subCategory in craft.categories({
        groupId: 2,
        descendantOf: parentCategoryObject,
        orderBy: 'title'
    }).all %}
        {# check if this subcategory has at least one entry assigned to it #}
        {% set subCatEntries = craft.entries({
            section: 'blog',
            relatedTo: subCategory,
            limit: 1
        }) %}

        {# display a link to the subcategory page if entries are assigned to it #}
        {% if subCatEntries|length %}
            <li><a href="{{ subCategory.url }}">{{ subCategory.title }}</a></li>
        {% endif %}
    {% endfor %}
</ul>

You'll need to provide the parentCategoryObject yourself based on however your templating works.