InputfieldCheckbox

The checked attribute and checked() method control whether the checkbox is checked. They are independent of the value attribute.

checked($checked = null)

Get or set the checked state. Returns bool.

// get checked state
$isChecked = $f->checked(); // true or false
// set checked (two equivalent ways)
$f->checked(true);
$f->attr('checked', 'checked');
// unset checked (two equivalent ways)
$f->checked(false);
$f->removeAttr('checked');

isEmpty()

Returns true when the checkbox is not checked.

if($f->isEmpty()) {
 // checkbox is unchecked
}

Standard behavior (default)

This mirrors how HTML checkboxes work. The value attribute holds what gets submitted if the checkbox is checked. Setting value does not affect checked state.

$f = $modules->get('InputfieldCheckbox');
$f->name = 'notify';
$f->label = 'Email notifications';
// set what value is stored when checked (default is 1)
$f->attr('value', 'yes');
// separately control whether it starts checked
$f->attr('checked', 'checked');

After processInput(), $f->val() returns checkedValue ('yes') if checked, or uncheckedValue ('') if not.

autocheck mode

When autocheck is 1, setting a non-empty value also makes the checkbox checked. This is useful for standalone forms where you want to pre-populate a checked state by setting a value directly.

$f->autocheck = 1;
$f->val('yes'); // sets checkedValue to 'yes' AND makes it checked

Without autocheck, that same val('yes') call would set the checkedValue but leave the checkbox unchecked.

checkedValue and uncheckedValue

These control what gets stored after the form is processed.

$f->checkedValue = 'active';
$f->uncheckedValue = 'inactive';
// after processInput():
// $f->val() === 'active' when checked
// $f->val() === 'inactive' when not checked

When checkedValue is set to anything other than 1, it is also used as the label displayed next to the checkbox (if no label2 or checkboxLabel is set).

$f->checkedValue = 'Subscribe to newsletter';
// renders: [✓] Subscribe to newsletter

The label displayed next to the checkbox is resolved in this order:

1. checkboxLabel (from admin config, supports multi-language)
2. label2 (set via API)
3. checkedValue (when set to something other than 1)
4. label (the main field label, as fallback)

Set checkboxOnly = true to suppress the label entirely and render only the checkbox input.

// separate field label from checkbox label
$f->label = 'Email notifications'; // shown above the field
$f->label2 = 'Send me email updates'; // shown next to the checkbox
// or show no label next to checkbox
$f->checkboxOnly = true;

• After processInput(), $f->val() returns checkedValue or uncheckedValue — not true/false.
• The skipLabel behavior is set automatically: skipLabelFor when a checkbox label or description is present, skipLabelHeader otherwise.
• label2 and checkboxLabel do the same thing. Use label2 when configuring via API; checkboxLabel is the admin-configurable version.
• checkedValue and uncheckedValue are only available in the admin config when hasFieldtype is false (standalone forms). When used with a Fieldtype (e.g. FieldtypeCheckbox), those values are managed by the Fieldtype.
• Source file: wire/modules/Inputfield/InputfieldCheckbox/InputfieldCheckbox.module