Using the acf validation filters it is possible to prevent the user from selecting the same choice more than once.
Let’s say that you have a repeater field with a key of ‘field_0123456789abc’ and it has a sub field with a key of ‘field_cba9876543210’ and you want to make sure that the sub field in each rows has a unique value.
<?php
// validate one row of a repeater against other rows of same repeater
add_filter('acf/validate_value/key=field_cba9876543210', 'sub_field_unique', 10, 3);
function sub_field_unique($valid, $value, $field, $input) {
if (!$valid) {
return $valid;
}
$repeater = 'field_0123456789abc';
$subfield = 'field_cba9876543210';
$values = $_POST['acf'][$repeater];
if (!count($values)) {
return $valid;
}
// extract the current row index from $input
$current_row = preg_replace('/^\s*acf\[[^\]]+\]\[([^\]]+)\].*$/', '\1', $input);
$count = count($values);
foreach ($values as $index => $row) {
if ($index != $current_row && $value == $row[$subfield]) {
$valid = 'value must be unique';
}
}
return $valid;
}
?>
The exact logic may be different depending on the field type.
