Form::getAttributesHTML() incorrectly escaped in templates

[kinglozzer]

Affected Version

4.x

Description

Forms and form fields have two methods of outputting HTML attributes, $AttributesHTML and $getAttributesHTML('class'), where the 2nd example will output all attributes except the class attribute.

IIRC the reason behind this is that $AttributesHTML will call getAttributesHTML() but won’t pass through any arguments (this was an opinionated design decision in the template engine because getters traditionally shouldn’t have arguments), so it’s necessary to include the get prefix if you want arguments included.

Form is missing 'getAttributesHTML' => 'HTMLFragment' from its casting array. The AttributesHTML trait actually mentions this requirement in its documentation:

silverstripe-framework/src/View/AttributesHTML.php

Lines 10 to 16 in 673c114

	* When applying this trait to a class, you also need to add the following casting configuration.
	* ```
	* private static $casting = [
	* 'AttributesHTML' => 'HTMLFragment',
	* 'getAttributesHTML' => 'HTMLFragment',
	* ];
	* ```

With this casting missing, using $getAttributesHTML('class') on a Form instance in templates results in escaping on quotes for the attribute values

[michalkleiner]

Closing as linked PR merged.