kernelRootDir = $kernelRootDir; } public function buildView(FormView $view, FormInterface $form, array $options) { // Pass this flag is necessary to render the label as raw. // See below the twig field template for more details. $view->vars['raw_label'] = true; } public function configureOptions(OptionsResolver $resolver) { $resolver->setDefaults([ 'attr' => [ // It's the key of the solution and can be done in many ways. // Now, the rendered element will have a new font. 'style' => "font-family: 'FontAwesome';", 'class' => "select2-icon" ], 'choices' => $this->getFontAwesomeIconChoices(), ]); } public function getParent() { return ChoiceType::class; } protected function getFontAwesomeIconChoices() { if (null !== $this->choices) { return $this->choices; } $fontAwesome = file_get_contents($this->kernelRootDir); $pattern = '/\.(fa-(?:\w+(?:-)?)+):before\s+{\s*content:\s*"\\\\(.+)";\s+}/'; if (preg_match_all($pattern, $fontAwesome, $matches, PREG_SET_ORDER)) { foreach ($matches as list(, $class, $code)) { $this->choices[$class] = $class; } ksort($this->choices); } return $this->choices; } }