Building a form in Symfony involves several steps, including creating a form class, defining the form fields, rendering the form, validating form data, and saving the data to the database. In this tutorial, we will go through these steps in detail and provide code examples to help you understand the process.

Create a form class:
The first step in building a form in Symfony is to create a form class. This class will represent the form and contain the logic for rendering and processing the form data. To create a form class, create a new file in the src/Form directory of your Symfony project and add the following code: 

<?phpnamespace App\Form;use App\Entity\Newentity;use Symfony\Component\Form\AbstractType;use Symfony\Component\Form\Extension\Core\Type\CheckboxType;use Symfony\Component\Form\Extension\Core\Type\SubmitType;use Symfony\Component\Form\FormBuilderInterface;use Symfony\Component\OptionsResolver\OptionsResolver;class NewformType extends AbstractType{ public function buildForm(FormBuilderInterface $builder, array $options): void { $builder ->add('Newname') ->add('Newemailid') ->add('Newphone') ; } public function configureOptions(OptionsResolver $resolver): void { $resolver->setDefaults([ 'data_class' => Newentity::class, ]); }}

In the code above, we have created a form class named ContactFormType that extends the AbstractType class from the Symfony\Component\Form\AbstractType namespace. The buildForm method is used to define the form fields, which in this case are name, email, and message. The configureOptions method sets options for the form, such as the data class and validation constraints.

Define the form fields:
To define the form fields, we use the add method on the form builder object. The add method takes the field name as the first argument and the field type as the second argument. In the example above, we have defined three fields: name, email, and message. By default, these fields will be rendered as text inputs. If you want to use a different field type, such as a text area or a checkbox, you can pass the field type as the second argument to the add method. For example:

 $builder ->add('Newname') ->add('Newemailid') ->add('Newphone') ->add('submit', SubmitType::class) ;

Render the form:
To render the form, we need to create a controller in our Symfony application. In the controller, we can use the createForm method from the Symfony\Component\Form\FormFactory service to create an instance of the form class. The createForm method takes the form class as the first argument and any additional options as the second argument. For example:

 $form = $this->createForm(NewformType::class, $new); return $this->render('new/index.html.twig', ['form'=>$form->createView()]);