DOC Document including attributes in formfield schema data

en/08_Changelogs/6.0.0.md

@@ -36,6 +36,7 @@ title: 6.0.0 (unreleased)
   - [MySQL now defaults to utf8mb4](#mysql-utf8mb4)
   - [`DBDecimal` default value](#dbdecimal-default-value)
   - [`RedirectorPage` validation](#redirectorpage-validation)
+  - [`getSchemaDataDefaults()` now includes attributes](#formfield-schema-data)
 - [Full list of removed and changed API (by module, alphabetically)](#api-removed-and-changed)
 
 ## Features and enhancements
@@ -910,6 +911,28 @@ Previously if an invalid default value was provided for a [`DBDecimal`](api:Silv
 
 [`RedirectorPage`](api:SilverStripe\CMS\Model\RedirectorPage) now uses the [`Url` constraint](https://symfony.com/doc/current/reference/constraints/Url.html) from `symfony/validator` to validate the `ExternalURL` field. It will no longer add `http://` to the start of URLs for you if you're missing a protocol - instead, a validation error message will be displayed.
 
+### `getSchemaDataDefaults()` now includes attributes {#formfield-schema-data}
+
+The [`FormField::getSchemaDataDefaults()`](api:SilverStripe\Forms\FormField::getSchemaDataDefaults()) method (and by extension the [`getSchemaData()`](api:SilverStripe\Forms\FormField::getSchemaData()) method) now calls [`getAttributes()`](api:SilverStripe\Forms\FormField::getAttributes()). This was done so that attributes such as `placeholder` can be used in the react components that render form fields.
+
+In the past it was common to call `getSchemaData()` inside the `getAttributes()` method, so that a form field rendered in an entwine admin context had the data necessary to bootstrap a react component for that field. Doing that now would result in an infinite recursion loop.
+
+If you were calling `getSchemaData()` in your `getAttributes()` method in a `FormField` subclass, we recommend you include the schema data in the template directly instead. For example:
+
+```diff
+-public function getAttributes()
+-{
+-    $attributes = parent::getAttributes();
+-    $attributes['data-schema'] = json_encode($this->getSchemaData());
+-    return $attributes;
+-}
+```
+
+```diff
+-<div $AttributesHTML></div>
++<div $AttributesHTML data-schema="$SchemaData.JSON"></div>
+```
+
 ### Full list of removed and changed API (by module, alphabetically) {#api-removed-and-changed}
 
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