Preserving Checkbox Values in FormLister After Validation Errors

Checkbox state is one of the easiest things to lose in a form after validation fails. the discussion behind this article described a classic FormLister case: text fields were restored correctly after an error, but checked boxes became unchecked and users had to start over.

The fix is to render checkbox inputs from the same value source that FormLister uses for other fields. In other words, the form has to look at the current submitted values when deciding whether checked should be present.

Typical checkbox pattern

<input type="checkbox" name="tehnika[]" value="Oven" [+tehnika:contains=`Oven`:then=`checked`+]>

The exact modifier can vary depending on your project templates, but the main idea stays the same: never hardcode the checkbox markup as static HTML when the field has to survive validation errors. Bind it to the submitted value instead.

Why it matters

• users do not lose multi-select choices after one validation mistake
• long forms feel much more reliable
• checkbox arrays remain consistent in both the UI and the email/report output

This is a small UX fix, but it removes one of the most frustrating failure modes in large request forms, configurators, and quote forms.