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User-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/127.0.0.0 Safari/537.36
Operating System: Microsoft Windows 10 Enterprise Version 22H2 (OS Build Version 10.0.19045.4780)

Requirement:

We just want to be able to trigger a validation check independently of submitting the form.

Alternative approaches

I’ve tried to configure a button in several ways to trigger “show validations”; one such way was configuring the action to “Event”. When a button configured with its action set as “Event” is in a form, when the button is pressed an error message is presented “Custom button events not supported yet. Event Type: …” This error message breaks the users immersion in the process of filling out their form. Once the ok button associated with this error message is pressed, then the error message is closed and then the validation error(s) are displayed.

James identified the following:

Around line 965 of the app\frontend\src\components\designer\FormViewer.vue
This was introduced by Jason C. 9 months ago, not sure if it was stubbed for a reason but if the alert could change to a console.log then it will work for validation.

    // Custom Event triggered from buttons with Action type "Event"
    onCustomEvent(event) {
      alert(i18n.t('trans.formViewer.customEventAlert', { event: event.type }));
    },