Fields associated with a category group I have set up a custom field for a category group. How do I get the value of this field in a loop that goes through entries? Each category in the group could have this field's value set as true or false (light switch). I.e. I need to see what category is related to the current entry and then look up the value of this field - there is some html I want to show only if the value is true.
You can access a category's fields exactly like you
access an entry's fields.

{{ category.myLightswitch }}


So this should do it for your categories loop:

{% for entry in entries %}
    {% for category in entry.myCategoriesField %}

        {{ category }}

        {% if category.myLightswitch %}
            EXTRA
        {% endif %}

    {% endfor %}
{% endfor %}