Drupal 8 Custom module - how to create a field in the admin area, and then pull that input in my module to use? - drupal-modules

Question

New to Drupal 8, I'm coming from the WP world so it's been very confusing getting the hang of things. I created a custom module and have a page outputting text. Where I'm stuck is the ability to make a field in the admin area, pull that saved info, and then use it in my content that's being output.
Been following along with tutorial but am very stuck. Can anyone provide a road map for me or helpful articles to accomplish this?

Answer 1

Suppose your module name is "custom" then follow these steps to create a admin form and pull the saved info on admin page.
Create a folder name "custom".
Create "custom.info.yml" file within "custom" folder.
name: custom
description: Show admin saved data through custom module.
type: module
# core: 8.x
configure: admin/config/services/custom
Create a Permission for who access admin form.
For Permission create "custom.permissions.yml" file within "custom" folder.
'administer custom':
'title': 'Administer Customform'
'description': 'Configure how Custom Form is used on the site.'
restrict access: true
Then create a route for custom admin form path & it's content.
Create "custom.routing.yml" file within "custom" folder.
custom.config:
path: '/admin/config/custom/config'
defaults:
_form: '\Drupal\custom\Form\CustomConfigForm'
_title: 'Custom Configuration'
requirements:
_permission: 'administer custom'
Now create a menu and assign this route ("custom.config") in menu path & create a form within custom folder and the form location is
src/Form/CustomConfigForm.php
For menu create a "custom.links.menu.yml" file within "custom" folder.
custom.config:
title: 'Custom '
description: 'Custom Admin Configuration'
parent: system.admin_config
route_name: custom.config
weight: 100
For admin form create CustomConfigForm.php file within custom folder and the file location is src/Form/CustomConfigForm.php
<?php
namespace Drupal\custom\Form;
use Drupal\Core\Form\ConfigFormBase;
use Drupal\Core\Form\FormStateInterface;
class CustomConfigForm extends ConfigFormBase {
public function getFormId() {
return 'custom_config_form';
}
public function buildForm(array $form, FormStateInterface $form_state) {
$config = $this->config('custom.settings'); // store data in custom.settings
$form = parent::buildForm($form, $form_state);
$form['custom_types'] = array(
'#type' => 'checkboxes',
'#title' => t('Content Types'),
'#description' => t('Configure where the custom button should appear.'),
'#options' => node_type_get_names(),
'#default_value' => $config->get('custom_types', array()),
);
return $form;
}
public function submitForm(array &$form, FormStateInterface $form_state) {
$config = $this->config('custom.settings');
$config->set('custom_types', $form_state->getValue('custom_types'));
$config->save(); // save data in custom.settings
return parent::submitForm($form, $form_state);
}
public function getEditableConfigNames() {
return ['custom.settings'];
}
}
Now when you save admin form then after you fetch the saved data in "custom.module" file to use this code.
Create "custom.module" file within custom folder.
$config = \Drupal::config('custom.settings'); // get saved settings
$types = $config->get('custom_types', array()); // fetch particular saved data "custom_types"
print $types;
Now enable this module.
Your admin form path is YOUR_SITE_NAME/admin/config/custom/config
Also in Drupal 8 sometimes cache problem occurs, so if any problem comes then clear the cache after form save.