How to invoke a service after pressing submit in Drupal - php

Question

I am very new to Drupal and I am asked to create form with a submit button and a service that makes a get request to an API with the values from the form. The API is a simple API that the user can enter a country and it will return a response with the correct greeting from that country.
This is my routing file:
hello_world.salutation:
path: '/hello'
defaults:
_controller: Drupal\hello_world\Controller\HelloWorldSalutation::salutation
_form: Drupal\hello_world\Form\GreetingForm
_title: 'Get a greeting from a different language'
requirements:
_permission: 'administer site configuration'
First problem is that I do not know how to make the form and the controller in the same routing,
and second is that I do not know how to invoke that service when the user has entered submit.
Here is my services file:
services:
hello_world.salutation:
class: Drupal\hello_world\HelloWorldSalutation
arguments: [ '#config.factory' ,'#tempstore.private']
cache.nameofbin:
class: Drupal\Core\Cache\CacheBackendInterface
tags:
- { name: cache.bin }
factory: [ '#cache_factory', 'get' ]
arguments: [ nameofbin ]
I will skip some lines from the GreetingFrom class to keep it simple, but I can add them if it is required.
Here is the submitForm function from the GreetingForm class. The idea is to put the input in a global tempstore so I cal access the values from the controller I guess.
public function submitForm(array &$form, FormStateInterface $form_state)
{
$search_str = $form_state->getValue('greeting');
// check the input
$params['items'] = $form_state->getValue('greeting');
// 2. Create a PrivateTempStore object with the collection 'greetingForm_values'.
$tempstore = $this->tempStoreFactory->get('greetingForm_values');
// 3. Store the $params array with the key 'params'.
try {
$tempstore->set('params', $params);
} catch (\Exception $error) {
// dump the error for now, read error, --fix this!
dpm($error);
}
}
And the salutation function from the controller looks like this:
public function salutation()
{
$tempstore = $this->tempStoreFactory->get('greetingForm_values');
$params = $tempstore->get('params'); // this value should come from the search form
return [
'#markup' => $this->salutation->getGreeting($params),
];
}
Any help is greatly appreciated, and please ask for more information if it is needed.

Answer 1

Routing file
In your use case I believe you can stick to the use of a Form. Please discard the Controller specification from your hello_world.salutation route, because it should be either _form or _controller, not both for a single route.
Service method invocation
For your service definition, you can do this by either statically calling the service as:
$salutation_service = \Drupal::service('hello_world.salutation');
$salutation_service->somePublicMethodCall();
or via Dependency Injection which I assume you are already doing when I look at this->salutation->getGreeting($params)?
Form x Controller
From the provided details, I can't really tell why you need the Controller, but if you need to redirect to the Controller, then you could create a separate route for your HelloWorldSalutation::salutation() method and redirect to it from GreetingForm ::submitForm() via the $form_state object:
$url = \Drupal\Core\Url::fromRoute('hello_world.salutation');
$form_state->setRedirectUrl($url);