Create custom module for render custom forms through a controller in Drupal 8 - drupal-8

Question

I need to render a custom form which is created using Drupal\Core\Form\FormBase and Drupal\Core\Form\FormStateInterface through a controller in custom Drupal 8 module. Is there any guidence or reference to follow to do this?
Actually I tried to render form directly and through a controller. But both ways are not working. Only render the submit button. I refer the drupal 8 documentation also. But I couldn't find a solution for this. Please be kind enough to find my coding samples below. If there are anything wrong. Please correct me.
my_module.routing.yml
partner.content:
path: '/partner'
defaults:
_controller: '\Drupal\partner\Controller\PartnerController::add'
_title: 'Add Partner'
requirements:
_permission: 'access content'
partner.addform:
path: '/partner/add'
defaults:
_form: '\Drupal\partner\Form\AddForm'
_title: 'Add Partner'
requirements:
_permission: 'access content'
AddForm.php
namespace Drupal\my_module\Form;
use Drupal\Core\Form\FormBase;
use Drupal\Core\Form\FormStateInterface;
class AddForm extends FormBase
{
/**
* Returns form id
*
* #return string
*/
public function getFormId(): string
{
return 'my_module_add_form';
}
/**
* Build form array
*
* #param array $form
* #param FormStateInterface $formState
* #return array
*/
public function buildForm(array $form, FormStateInterface $form_state): array
{
// First name
$form['first_name'] = [
'#type' => 'textField',
'#title' => t('First Name'),
'#required' => true,
];
// Other input fields...
$form['submit'] = array(
'#type' => 'submit',
'#value' => $this->t('Save Changes'),
'#button_type' => 'primary',
);
return $form;
}
public function validateForm(array &$form, FormStateInterface $form_state) {}
public function submitForm(array &$form, FormStateInterface $form_state) {}
}
MyModuleController.php
<?php
namespace Drupal\my_module\Controller;
use Drupal\Core\Controller\ControllerBase;
use Drupal\my_module\Form\AddForm;
class MyModuleController extends ControllerBase
{
public function add()
{
$addForm = new AddForm();
$form = \Drupal::formBuilder()->getForm($addForm);
return [
'#theme' => 'form_my_module_add',
'#form' => $form,
];
}
}

Answer 1

Happy to find out the solution with Hemantha Dhanushka on my comment.
To make it clear this question has a correct answer, here I past the validated comment.
I would recommend you to use the first approach (using routing::_form instead
of Controller). Also, it seems you use the wrong #type for your
first_name field. Try textfield instead of textField.
Also, for people who want to go further, here are some links to implement a proper
routing::_form approach to expose a form as a page instead of using a Controller: https://www.valuebound.com/resources/blog/step-by-step-method-to-create-a-custom-form-in-drupal-8.
For people looking for more help about existing Form Element Reference (textfield, checkboxes, entity_autocomplete, ...) here is an excellent up-to-date article https://drupalize.me/tutorial/form-element-reference?p=2766

Answer 2

You can use buildForm() method for it. Check below code example:
public function add()
{
$form_state = new Drupal\Core\Form\FormState();
$form_state->setRebuild();
$form = \Drupal::formBuilder()->buildForm('Drupal\my_module\Form\AddForm', $form_state);
return [
'#theme' => 'form_my_module_add',
'#form' => $form,
];
}
Reference: https://api.drupal.org/api/drupal/core!lib!Drupal!Core!Form!FormBuilder.php/function/FormBuilder::getForm/8.2.x