Display only one Category and its sub-categories

Question

I have created a custom filter.xml to search for specific documents. Using Joomla's category system, I have also create 3 main categories. Courtrolls, Newsletter and communique.

In my filter form, I have the following field:

<field type="category"
       category="19"
       name="roll"
       extension="com_courtroll"
       label="Select a category"
       description=""
       default="19"
/>

The problem is that I only want to have Courtrolls and its subcategories in this field, but it shows all my components categories.

Answer 1

You could use the SQL form field type type to get the right categories + their catids. See: https://docs.joomla.org/SQL_form_field_type

Or better: create for your component its own Fields that you load in that XML. See for example how Joomla 4 uses Fields for the com_content component: https://github.com/joomla/joomla-cms/tree/4.2-dev/administrator/components/com_content/src/Field