Resolved value is incorrect for groups of multiple checkboxes in PrimeVue Forms

[PotatoesMaster]

Describe the bug

Using PrimeVue Forms, when a group of checkboxes is present, the form state does not include all the values but only the state for the last changed checkbox.

Pull Request Link

No response

Reason for not contributing a PR

• Lack of time
• Unsure how to implement the fix/feature
• Difficulty understanding the codebase
• Other

Other Reason

I think I located the problem: in packages/forms/src/useform/index.js. The state is overwritten with the last checkbox changed.

I don't know how to fix that: I think the state should be an array when several checkboxes with the same name are present in the form, but I am unsure of how to check for this condition and prevent issues with single checkboxes.

Reproducer

https://stackblitz.com/edit/primevue-forms-checkbox-group-issue?file=src%2FApp.vue

Environment

Vue version

3.5.13

PrimeVue version

4.2.5

Node version

20.18.0

Browser(s)

No response

Steps to reproduce the behavior

1. In a PrimeVue Form, include several checkboxes having the same value for the "name" attribute and different values for the "value" attribute.
2. Change field value or submit the form.
3. The resolved field value is an array containing the value of the lastly checked checkbox, or it is empty if the last action was to uncheck a checkbox.

Expected behavior

I expect the resolved value to be an array containing the values of all the checked checkboxes, or to be empty if none are selected.