Reply To: Validation of a field based on the value of another field

• John Huebner

• May 29, 2019 at 3:10 am

Looking back yet again because I got a notice that there was a reply, the code I posted will do nothing because the fields you’re trying to validate are part of a flex field layout. This means that they are sub fields and the ACF input will look something like

$_POST['acf'] == array(
  'field_XYZ' => array( // the field key of your flex field
    // nested array for each rows
    array(
      'field_ABC' => 'first field in row',
      'field_DEF' => 'second field in row'
    ),
  ),
);

In order to validate one of these fields against the other field the first thing you need to do is find the right row.

finding the current row

// a function that finds a row in the acf input
// that has a sub field with a specific key
function get_current_acf_row_from_input($key, $input) {
  
  // get a list of each input index
  preg_match_all('/\[([^\]]+)\]/', $input, $matches);
  // the list of indexes will be in $matches[1]
  $matches = $matches[1];
  
  // start at the top
  $row = $_POST['acf'];
  $count = count($matches)-1;
  
  // loop over each index
  for ($i=0; $i<$count; $i++) {
    // set row to the row[index]
    $row = $row[$matches[$i]];
    // see if the field key we're looking for is in this row
    if (isset($row[$key])) {
      // it is, found it
      break;
    }
  }
  if (!isset($row[$key])) {
    // did not find a matching row
    $row = false;
  }
  
  return $row;
} // end public function validate_condition_value

Then you can modify the filter like this

// conditionally require video field IF playlist ID field is blank
add_filter('acf/validate_value/key=field_5c7ea3fd1ff26', 'acf_validate_video', 10, 4);

function acf_validate_video($valid, $value, $field, $input) {
  // bail early if value is already invalid
  if( !$valid ) { return $valid; }
  
  $key = 'field_5c7ea3fd1ff26';
  $row = get_current_acf_row_from_input($key, $input);
  if ($row === false) {
    // the row was not found
    // this should not happen, but, one never knows
    return $valid;
  }
  // check that this value and the value of the other field are not both empty
  if (empty($row['field_5c8fe92190fd6']) && empty($value)) {
    $valid = __('You must select a video if no Playlist ID is defined.');
  }
  return $valid;
}