---
title: "Content Fields Hooks and Filters Reference"
url: https://nexterwp.com/docs/nexter-fields-hooks-reference/
date: 2026-11-12
modified: 2026-11-12
lang: en
author: "Aditya Sharma"
description: "Content Fields exposes filters and actions so you can change how values are read and written, override how post types and taxonomies register, and react when a definition changes —..."
image: https://nexterwp.com/wp-content/uploads/2026/09/nexter-fields-hooks-reference-1024x519.jpg
word_count: 491
---

# Content Fields Hooks and Filters Reference

Content Fields exposes filters and actions so you can change how values are read and written, override how post types and taxonomies register, and react when a definition changes — without touching plugin code.

## What It Does

Nexter Extension 4.9.0 ships **18 filters** and **4 actions** in Content Fields. This page lists all of them with their signatures; the linked pages cover the ones you are most likely to use.

## Before You Start

- Nexter Extension 4.9.0 or later with Content Fields enabled.- Somewhere to add PHP — a child theme’s `functions.php`, a small plugin, or a Nexter code snippet.- You know the field or post type key you want to affect.

## Add a Hook

- Put the code in a child theme, a small plugin, or a Nexter code snippet — never in the plugin itself, which an update would overwrite.

![A field group open in the builder, showing the field names hooks are keyed on](https://nexterwp.com/wp-content/uploads/2026/09/nxt-fields-h-shared-add-field.webp)

- Hook early enough. Value filters run whenever a value is read or written, so ordinary `add_filter()` placement is fine.

- Always return a value from a filter. Returning nothing replaces the value with `null`.

- Check the field or key first, so your change applies only where you mean it to.

## Display the Value

Every hook in Content Fields 4.9.0, with its signature:

`// ---- Values -------------------------------------------------------------
apply_filters( 'nxt/format_value', $value, $field, $object_id );
apply_filters( 'nxt/update_value', $value, $field, $object_id );
apply_filters( 'nxt/pre_load_field', null, $selector, $object_id );
apply_filters( 'nxt/load_field', $value, $selector, $object_id );
apply_filters( 'nxt/pre_format_field_value', null, $value, $field );
apply_filters( 'nxt/pre_sanitize_field_value', null, $raw, $field, $renderer );

// ---- Field types and rendering ------------------------------------------
apply_filters( 'nxt/field_type_catalog', $catalog );
apply_filters( 'nxt/render_field_input', false, $field, $meta_key, $input_name, $value, $value_exists, $renderer );

// ---- Registration -------------------------------------------------------
apply_filters( 'nxt/register_post_type_args', $cpt_args, $key, $args );
apply_filters( 'nxt/register_taxonomy_args', $params, $key, $args );
apply_filters( 'nxt/validate_cpt_supports', null, $supports );
apply_filters( 'nxt/register_field_meta', true, $field, $meta_key, $object_type );
apply_filters( 'nxt/register_field_meta_args', $args, $field, $meta_key, $object_type );
apply_filters( 'nxt/pre_field_meta_rest_config', null, $field );

// ---- Migration ----------------------------------------------------------
apply_filters( 'nxt/import_sources', $sources );

// ---- Storage and capabilities -------------------------------------------
apply_filters( 'nexter_content_types_model_dir', $dir );
apply_filters( 'nexter_content_types_non_grantable_capabilities', $caps );
apply_filters( 'nexter_content_types_unsafe_capability_targets', $unsafe );

// ---- Actions ------------------------------------------------------------
do_action( 'nxt/definition_saved', $post_id, $kind, $meta );
do_action( 'nxt/definition_changed', $post_id, $kind );
do_action( 'nxt/registered_post_type', $key, $object, $args );
do_action( 'nxt/registered_taxonomy', $key, $object, $args );`

## Limitations

- These hooks are specific to Nexter Content Fields. They are not compatible with ACF’s hooks, and ACF snippets will not work unchanged.- Value filters run on every read or write of a field. Keep the callbacks cheap — a slow filter is felt on every page that renders fields.- Hook names are a contract. Treat anything not listed here as internal and liable to change.

## Troubleshooting

### My filter runs but the value is unchanged

Check you are returning the value. A callback that ends without a `return` hands back `null`, and Nexter treats that as no value.

### My filter affects every field, not one

Test the `$field` or `$selector` argument and return the original value untouched for everything else.

## Related Docs

- [Change a field value before it is displayed](https://nexterwp.com/docs/nxt-format-value-filter/)- [Change a field value before it is saved](https://nexterwp.com/docs/nxt-update-value-filter/)- [Template functions reference](https://nexterwp.com/docs/nexter-fields-template-functions/)