With a categories field, how do I query only the *selected* categories?

Question

Suppose we have a category group that allows for any number of levels to its structure. We also have a category field that allows for choosing any number of categories from that group.

In our example, we want to select three categories: one is a level 1 category in that group, another is a direct child of a different level 1 category and the third is a level 4 category from another branch in the category group (all three are in different branches for this example).

The question is: How do we query the category field to only return the categories we selected—the categories we actually clicked on when selecting categories? (Craft 3)

Answer 1

Here's how to isolate only your chosen categories. This works off the premise that if a related category is a parent of one of the other related categories, it is not a category you chose.

{% set relatedCategories = entry.myCategoryField.with(['parent']).all() %}
{% set parentCategories = relatedCategories | map(c => c.parent) %}
{% set chosenCategories = relatedCategories | diff(parentCategories) %}

Answer 2

Craft does not allow for this (as of Craft 3.1.34). When saving selected categories to a Category relationship field, it automatically assigns the parent categories and does nothing to designate which categories were actually selected/clicked/chosen.

Answer 3

Unless I'm missing something - this is how you run through the categories you selected in your Category field when you're looking at that entry's template:

{% for cat in entry.yourCategoryFieldhandle.all() %}
    {{ cat.title }}
{% endfor %}

EDIT: Ignore this, I can see what you mean. If you select a child category it automatically selects all the parents too.

This may not be suitable for your site, but if this is required functionality I'd be looking at using a Structure instead of categories. Using a Structure combined with an Entries field will let you do this no problem. P&T are going to be removing Categories and Tags in Craft 4 anyway.

Answer 4

This is untested, but you could do a loop within each category to compare it and figure out if it's the end of a branch. I've probably missed something in my code but it might help as a start.

{% set catsYouWant = [] %}
{% for cat in entry.yourCategoryFieldhandle.all() %}

    {% set possible = false %}

    // If category is level one it is possibly the end of branch
    {% if cat.level == 1 %}
        {% set possible == true %}
    {% endif %}

    // Compare category against others to see if is a parent, if so we can discount it
    {% for catCompare in entry.yourCategoryFieldhandle.all() %}

        // if catCompare is child of cat then cat is not end of branch
        {% if catCompare.ancestorOf(cat) %}
            {% set possible = false %}
        {% endif %}

    {% endfor %}

    {% if possible == true %}
        {% set catsYouWant = catsYouWant|merge(cat) %}
    {% endif %}
{% endfor %}