Elements with #has_garbage_value and #value are always set as a triggering element

Thank you everyone for this.

Closing as outdated as there hasn't been a follow up for #22

If still a bug please reopen updating issue summary for D10

Thanks!

This is absolutely still a bug in Drupal 11.

Button Field module documents:

Important note

Due to #1452894: Elements with #has_garbage_value and #value are always set as a triggering element you can not use image buttons on edit forms when there are any other buttons. Non-editable displays are unaffected.

And where i'm coming from, i confidently told Gin in 🐛 Image buttons cannot be kept in Gin's sticky form actions Active that core's image button form element is a valid alternative to a standard submit input form element:

As noted in ✨ UX when using gin with Contnet Moderation and Workflows Active , Workflow Buttons module pairs very well with Gin for improving the experience of using content moderation workflows, and the 2.0.x branch of Workflow Buttons' "Trash workflow" submodule switches to using the image button to have a trash icon for the soft-delete, similar to the trash icon Claro/Gin add to core's delete link. […]

But in short swapping the submit button out and substituting an image button for it works, and Gin should support this core form element when adding Gin attributes and looking for the #gin_action_item flag.

And i get it working perfectly and then discover that no matter which button i press, the image button (soft delete!) is the one that gets incorrectly identified as the trigger button.

And it is not a duplicate with changing values client side; although that may be related, this is being caused with alteration in a Drupal form/widget alter.

Essentially the fix by wojtha in this issue 13 years ago and richthegeek and cvangysel in #873070: When an image button appears after another button in a form, the wrong triggering element and #submit handlers are detected → 14 years ago remains correct and needed.

When image buttons are clicked, browsers do not set NAME in the POST, instead setting NAME_x and NAME_y (with x and y the coordinates of the click). To get the clicked button we need to test for these parameters instead of the presence of value— that is, equally . (Damien's suggestion of using #value for image buttons also does not work, whether the button is pressed or not, whether it has a value or not, the value gets set anyway, and set to "true", presumably because of how image buttons are treated by the browser— the only thing that is safe to check are if coordinates were set.)

And yes (replying to 13 year old comments from another issue now, but the same feedback will come up) these changes make the alternative condition specific to image buttons, but i'm fairly certain that is because that is all there is— the only other element in core which uses #has_garbage_value is Radios, which aren't ever going to be triggering a form submission.

So, yeah, image buttons are ridiculous and Drupal core could totally deprecate them and not support them since basically nobody has cared for a decade (especially if we finally do 📌 Use form element type instead of Needs work ), but as long as we have ImageButton extending Submit we need to support it properly as an alternative to Submit, that works alongside Submit buttons.

The merge request is ready and works, but leaving Needs work as it needs a test showing that this fails even when value is not set in the initial form element definition. As my use case is altering an existing button there is some possibility that something about that is adding 'value' back, but definitely unsetting value is not enough.