How to programmatically build a page and a form in the same page

Question

What I'd like to do is build a page with two things:

• On one half of the page, custom markup with data from Drupal.
• On the other half, a custom form also submitted to Drupal.

There are a lot of tutorials on how to programmatically build pages in D8 (create route, extend controller, return render array, etc.). There are also a lot of tutorials on how to programmatically build forms on D8 (create route, extend form base, return render array, etc.). However, I could not find any resource on how to build both onto the same page.

How would I go about doing this?

Answer 1

You must use the formBuilder, like this:

$render = [];
$render['elememt1'] = [
  '#type' => 'markup',
  '#markup' => t('Test'),
];
$render['element2'] = \Drupal::formBuilder()->getForm('Drupal\MY_MODULE\Form\MyFormClass');// The destination of your form.

return $render;

Answer 2

Not sure if it fits to your project.

As a themer, I would create a form with Form Api in a custom module.

The I would create a custom block for this form :

src/Plugin/Block/HelloBlock.php

See here for a example :https://www.drupal.org/docs/8/creating-custom-modules/creating-custom-blocks/create-a-custom-block

I would then create a twig template for the page (what you call "custom markup with data from Drupal"). And Then I would integrate the custom block with the form.