$form = new Form(...); $field = $form->Fields()->dataFieldByName('email');
$fields = new FieldList( TextField::create('name')->setTitle('Name'), OptionsetField::create('rating')->setTitle('Rating')->setSource([1,2,3,4,5]) ); $emailField = $fields->dataFieldByName('email');In this example, we create a new FieldList object with two input fields (a text field and an option set field) using PHP package libraries. We then use the dataFieldByName method to attempt to retrieve an input field named 'email'. Since this field does not exist in the FieldList, the $emailField variable will be null. Based on these examples, it's likely that the package library in question is related to a PHP form or input field management framework such as SilverStripe, Laravel, or Symfony.