Render custom html below a custom form

Question

I am new to drupal, I am using drupal 8, I have develop a custom form by extending FormBase controller and i am trying to render it using a custom controller like below.

$form = $this->formBuilder->getForm('Drupal\xyz\Forms\XyzActionsForm',$parameter);

return [
  '#form'=>$form
]

This works fine form me. But now i also want custom html below this form so try below code

$form = $this->formBuilder->getForm('Drupal\xyz\Forms\XyzActionsForm',$parameter);

$form = render(form);

$form .= '<div>custom html </div>';

return [
  '#markup'=>$form
]

But this didn't work for me, Can anyone let me know how to achieve this.

Answer 1

You have to use the power of render arrays.

For your example, I would use something like that :

$form_class = 'Drupal\xyz\Forms\XyzActionsForm';
$form = [
  'form' => $this->formBuilder->getForm($form_class, $parameter),
  'custom' => [
    '#type' => 'container',
    'inside' => [
      '#markup' => 'custom html', // Or use the power of render with html_tag type
    ],
  ],
];

return $form;

Then you can manage cache and other stuff on your render array and build your response with it.