=======================
Add sub data processors
=======================

This guide shows how to add TypoScript-computed data — menus, record lists, plugin output — to a Content Block's `data`.

The problem it solves
=====================

Content Block fields hold editor-managed content. Sometimes the JSON needs computed data: a page tree menu, a list of the latest news records, or anything else a TYPO3 data processor can produce. Instead of writing that in `headless.php`, wire standard data processors via TypoScript.

Wire a sub data processor
=========================

..  code-block:: typoscript

    tt_content.vendor_yourcontentblockelement.fields.data.dataProcessing.10 {
        dataProcessing {
            10 = menu
            10 {
                levels = 2
                as = navigation
            }
        }
    }

What happens:

*   The path addresses the `nb-content-blocks-json` processor (setup position `10` inside `fields.data.dataProcessing`) that the Site Set defines for `lib.contentBlock`.
*   Inside it, `dataProcessing.` works exactly like everywhere else in TypoScript — any registered data processor can be used (`menu`, `database-query`, `files`, your own ...).
*   The `as` name of each sub processor becomes a new key in `data` (here: `data.navigation`).

Result
======

..  code-block:: json

    {
        "data": {
            "header": "My header",
            "navigation": [
                { "title": "Home", "link": "/" },
                { "title": "Products", "link": "/products/" }
            ]
        }
    }

The sub-processor results are merged into `data` after the Content Block fields; the internal keys `data` and `current` are stripped from the result first, so they cannot collide with your fields.

Notes
=====

*   Sub data processors run with the block's `ContentObjectRenderer` context — `field:` references in the sub processor resolve against the block's record.
*   This mechanism is used in production (e.g. dynamic card lists rendered by an additional processor with `as = cards`).
*   Prefer it over `headless.php <PostProcessWithHeadlessPhp.rst>`__ for anything TypoScript already provides.