Yoast SEO 27.8 — docs(customization-free): Document new wpseo_custom_fields_pre_query filter

docs/customization/yoast-seo/filters/custom-fields-pre-query-filter.md

@@ -0,0 +1,72 @@
+---
+id: custom-fields-pre-query-filter
+title: "Yoast SEO: Short-circuit the custom-fields lookup"
+sidebar_label: Short-circuit custom-fields lookup
+---
+Yoast SEO populates the custom-field autocomplete in the settings meta box by running a `SELECT DISTINCT meta_key` query against the `wp_postmeta` table. On sites with very large postmeta tables this query can become expensive.
+
+The `wpseo_custom_fields_pre_query` filter lets you short-circuit that query. When the filter callback returns a non-`null` value, the database query is skipped entirely and the returned array is used instead.
+
+## Parameters
+
+- `string[]|null $custom_fields` — Pre-computed list of meta key names, or `null` to run the default query.
+- `int $limit` — The configured result limit (default 30, from the `postmeta_form_limit` filter). Honor this value if running a custom query.
+
+## Example: supply a hardcoded list
+
+The simplest use case is returning a fixed list of known custom fields to avoid the database query entirely:
+
+```php
+<?php
+
+/**
+ * Replaces Yoast SEO's custom-fields DB query with a hardcoded list.
+ *
+ * @param string[]|null $custom_fields Pre-computed list, or null to run the default query.
+ * @param int           $limit         The configured result limit.
+ *
+ * @return string[] The list of custom field names.
+ */
+function my_custom_fields_list( $custom_fields, $limit ) {
+    return [
+        'my_seo_title',
+        'my_seo_description',
+        'my_custom_field',
+    ];
+}
+
+add_filter( 'wpseo_custom_fields_pre_query', 'my_custom_fields_list', 10, 2 );
+```
+
+## Example: supply a cached list
+
+For sites where the set of custom fields changes over time you can cache the result to avoid repeated queries:
+
+```php
+<?php
+
+/**
+ * Returns a transient-cached list of postmeta keys.
+ *
+ * Falls back to null (triggering Yoast SEO's own query) when the cache is empty,
+ * so the first uncached request still returns a complete list.
+ *
+ * @param string[]|null $custom_fields Pre-computed list, or null to run the default query.
+ * @param int           $limit         The configured result limit.
+ *
+ * @return string[]|null The cached list, or null to let Yoast SEO run its default query.
+ */
+function my_cached_custom_fields( $custom_fields, $limit ) {
+    $cached = get_transient( 'my_site_custom_fields' );
+
+    if ( is_array( $cached ) ) {
+        return $cached;
+    }
+
+    return null; // Let Yoast SEO run its default query and prime your cache separately.
+}
+
+add_filter( 'wpseo_custom_fields_pre_query', 'my_cached_custom_fields', 10, 2 );
+```
+
+Returning `null` (the default) causes Yoast SEO to run its built-in query unchanged.

sidebars.js

@@ -362,6 +362,7 @@ module.exports = {
 						"customization/yoast-seo/filtering-yoast-blocks",
 						"customization/yoast-seo/wp-get-environment-type-in-yoast-seo",
 						"customization/yoast-seo/filters/disable-opcache-reset-on-upgrade",
+						"customization/yoast-seo/filters/custom-fields-pre-query-filter",
 					],
 				},
 				{