Stop disabling attributes on the add to cart form when they only have 1 value

1. +++ b/modules/product/src/Plugin/Field/FieldWidget/ProductVariationAttributesWidget.php
   @@ -42,6 +42,45 @@ class ProductVariationAttributesWidget extends ProductVariationWidgetBase implem
   +    return [
   +        'enable_form_element' => FALSE,
   +      ] + parent::defaultSettings();
   

   Needs config schema update.

2. +++ b/modules/product/src/Plugin/Field/FieldWidget/ProductVariationAttributesWidget.php
   @@ -42,6 +42,45 @@ class ProductVariationAttributesWidget extends ProductVariationWidgetBase implem
   +    if ($this->getSetting('enable_form_element') == 1) {
   
   @@ -180,7 +219,7 @@ class ProductVariationAttributesWidget extends ProductVariationWidgetBase implem
   +      if ($attribute_element['#required'] && count($attribute->getValues()) === 1 && $this->getSetting('enable_form_element') == 0) {
   

   The default setting value is FALSE but we're checking 0.

I applied the patch, it applies, but when I do drush entup nothing is updated, the same with the drush updb.
When I go to the commerce configuration for product variation types after I cleared all caches, in the manage form display, I seem to not find/see the widget. I also tried adding a new field, still no luck with the widget. Maybe it's located somewhere else?

Br,
Dea

seem to not find/see the widget. I also tried adding a new field, still no luck with the widget. Maybe it's located somewhere else?

It adds a setting to the existing attribute selection widget on the order item purchased entity field. Check there.

Thank you for the guidance @mglaman. I found the widget and the add to cart button is present on the product. But I don't see the change when I disable or enable the widget on the default display or on the add to cart display. I have just one color available for a product and it is always shown, no matter what the widget says. I'm probablly doing something wrong here or the code is not working properly for me.

BR

Steps to Verify

1. Make sure the Order Items' "Add to Cart" form display is using the "Product Variation Attributes" widget.
2. Tick "Do not disable form element with single attribute value".
3. Add an attribute with a single value if you don't already have one, and make sure a product uses it.

Result

Before

After

+    $element['enable_form_element'] = [
+      '#type' => 'checkbox',
+      '#title' => $this->t('Do not disable form element with single attribute value'),
+      '#default_value' => $this->getSetting('enable_form_element'),
+    ];

The setting name has no relation to the label, and both feel odd (the description has a double negative, which takes a second to process).

Discussed with the team, we said that we should test to see if we can just remove the disabling completely. Don't even know if ajax is still triggered by a single option element.

+1 from me; disabling the form element is a bit of a hack here, simplifying form processing (i.e. we can safely disable it b/c a required single value element will have its value populated in the form state regardless) at the expense of visual changes on the front-end (the grayed out disabled element). Presumably we can disable the Ajax listener on the element if unnecessary Ajax refreshes is a problem.

Let's try this patch.

Confirmed that it doesn't trigger #ajax.

Tests are green. Committed.

Commit credit goes to jnrfred, for his earlier efforts.

Thanks, everyone!