Element validate; Check View is valid.
public function settingsFormValidate($element, &$form_state, $form) {
// Split view name and display name from the 'view_and_display' value.
if (!empty($element['view_and_display']['#value'])) {
list($view, $display) = explode(':', $element['view_and_display']['#value']);
}
else {
form_error($element, t('The views entity selection mode requires a view.'));
return;
}
// Explode the 'arguments' string into an actual array. Beware, explode()
// turns an empty string into an array with one empty string. We'll need an
// empty array instead.
$arguments_string = trim($element['arguments']['#value']);
if ($arguments_string === '') {
$arguments = array();
}
else {
// array_map() is called to trim whitespaces from the arguments.
$arguments = array_map('trim', explode(',', $arguments_string));
}
$value = array(
'view_name' => $view,
'display_name' => $display,
'arguments' => $arguments,
);
form_set_value($element, $value, $form_state);
}