How do I run hook_views_data_alter()?

Question

So I have already read and followed everything I could find on that issue:

1. putting my_module_views_data_alter(array &$data) in my_module.views.inc file in the root directory of my_module,
2. disabling cache for my view,
3. clearing caches million times,

but still I can never stop at a breakpoint inside this hook, nor can I see any effects of the code I have put in it.

What am I missing?

EDIT: updating with some code

In my_module I have already created a computed field user_age, calculating user age from a custom user profile field with date of birth.

my_module/my_module.module

function my_module_entity_base_field_info(EntityTypeInterface $entity_type) {
  if ($entity_type->id() === 'user') {
    $fields = [];
    $fields['user_age'] = BaseFieldDefinition::create('user_age_field')
      ->setName('user_age')
      ->setLabel(t('User age'))
      ->setComputed(TRUE)
      ->setClass('\Drupal\my_module\UserAgeIntegerItemList')
      ->setDisplayConfigurable('view', TRUE)
      ->setDisplayOptions('view', [
        'label' => 'hidden',
        'weight' => -5,
      ]);

    return $fields;
  }
}
function my_module_field_formatter_info_alter(array &$info) {
  $info['number_integer']['field_types'][] = 'user_age_field';
}

This field is working and is accessible in my user profile template.

Knowing that since Drupal 8.4

Computed fields can now be displayed by Views

I wanted to use field user_age as an exposed filter in my search_users view:

my_module/my_module.views.inc

/**
 * Implements hook_views_data_alter().
 */
function my_module_views_data_alter(array &$data) {
  if (isset($data['users_field_data'])) {
    $data['users_field_data']['user_age'] = [
      'title' => t('User age'),
      'field' => [
        'id' => 'my_module_view_user_age',
      ],
    ];
  }
}

my_module/src/Plugin/views/field/MyModuleViewUserAge.php

<?php

namespace Drupal\my_module\Plugin\views\field;

use Drupal\views\ResultRow;
use Drupal\views\Plugin\views\field\FieldPluginBase;

/**
 * A handler to provide proper displays for user user_age.
 *
 * @ingroup views_field_handlers
 *
 * @ViewsField("my_module_view_user_age")
 */
class MyModuleViewUserAge extends FieldPluginBase {

  /**
   * {@inheritdoc}
   */
  public function render(ResultRow $values) {
    $relationship_entities = $values->_relationship_entities;
    $age = '';
    // First check the referenced entity.
    if (isset($relationship_entities['user'])) {
      $user = $relationship_entities['user'];
    }
    else {
      $user = $values->_entity;
    }

    $type = get_class($user);
    if ($type === 'Drupal\user\Entity\User') {
      $age = $user->get('user_age')->getvalue();
    }

    return $age;
  }

  /**
   * {@inheritdoc}
   */
  public function query() {
    // This function exists to override parent query function.
    // Do nothing.
  }
}

but my_module_views_data_alter() seems to never be executed and user_age field is not present in the filter criteria for my view.

Answer 1

You can't xdebug in hook itself, you need to go to method calling this hooks which is in class ViewsData path /core/modules/views/src/ViewsData.php and put breakpoint in getData, clear cache and you will get what you need.

Answer 2

we should empty cache_default table. The only way I know is by MYSQL "TRUNCATE cache_default"

Answer 3

Here is an example MYMODULE.views.inc I've used recently in a module:

/**
 * Implements hook_views_data().
 */
function MYMODULE_views_data() {

  $data['schema_name']['nid'] = [
    'title' => t('NID'),
    'help' => t('NID from schema_name'),
    'field' => [
      'handler' => 'views_handler_field_numeric',
      'click sortable' => TRUE,
      'float' => TRUE,
      'id' => 'numeric',
    ],
    'relationship' => [
      'title' => 'NID',
      'label' => t('NID'),
      'help' => t('NID from schema_name'),
      'id' => 'standard',
      'base' => 'node',
      'base field' => 'nid',
      'relationship field' => 'nid',
      'handler' => 'views_handler_relationship',
    ],
    'sort' => [
      'id' => 'standard',
    ],
    'filter' => [
      'id' => 'numeric',
    ],
    'argument' => [
      'id' => 'numeric',
    ],
  ];

  return $data;

}

Some things I don't see in your code:

1. no handler for the views field
2. no filter or sort key for your field
3. not printing return $data; in your views.inc file

I know this is not a direct answer, but hoping it helps.