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So I was making a custom block, and implemented the build() method. 

public function build() {
    $result = $connection->db_query("SELECT n.title, u.uid, n.created    FROM node_field_data n, users u WHERE u.uid = n.uid AND n.type = :type ORDER BY n.created DESC LIMIT 5", array(
        'type' => 'article',
    ));
    $content = '';
    if ($result) {
        while ($row = $result->fetchAssoc()) {
            $content .= '<li>' . $row['title'] . '</li>';
        }
    } else {
        $content .= 'No blog posts to show';
    }

    return array(
        '#markup' => '<ul>' . $content . '</ul>',
    );
}

So this is a pretty basic helloworld kind of example calling the database. But db_query is deprecated with the following surgestion:

     * @deprecated as of Drupal 8.0.x, will be removed in Drupal 9.0.0. Instead, get
     *   a database connection injected into your service from the container and
     *   call query() on it. E.g.
     *   $injected_database->query($query, $args, $options);

The surgestion seemed kind of spacey not entirely knowing all of the expressions but i eventually fixed it with the following code:

    $connection = \Drupal::database();
    $result = $connection->query("SELECT n.title, u.uid, n.created FROM node_field_data n, users u WHERE u.uid = n.uid AND n.type = :type ORDER BY n.created DESC LIMIT 5", array(
        'type' => 'article',
    ));

to call the database.

My question is, \Drupal::database() is a static method, and i call it from inside of my own block, am i doing it wrong? or am i misunderstanding their meaning of dependency injection? if i had to do DI in other web programming i would find the DI container and configure it to give the database into my constructor or via a accessor method right?

Follow up questions is

  1. What exactly constitutes my container?

  2. What is "my service" referring to? my module maybe?

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3

Yes, you are doing it wrong by calling \Drupal::database.

Look at Drupal\block_content\Plugin\Block\BlockContentBlock in core as an example. The create() method gets the services and passes them to the __construct() method. That is the proper way.

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  • Okay, so i guess that the static create method are being called by the DI container? i then register the dependencies my block will need, and i accept them chronologically in the constructor, allright. But the example you linked uses the entityManagers loadEntityByUuid method, which is deprecated. I think the entity manager was the only dependency that looked like a "database thing". What object to do surgest i subscribe to in the create method? :). thanks for the answer btw. – DenLilleMand Dec 15 '15 at 15:28
  • Which service to inject? Probably entity.query and do this with an entity query (google it) instead of a direct database query. But looking at the query you wrote, this may be possible with a View that creates a block. – cilefen Dec 15 '15 at 15:55
  • Here is a video of a similar example, in a controller, not a block, with usage of the create() method (which by the way you seem to grasp, others may benefit): knpuniversity.com/screencast/drupal8-under-the-hood/… – cilefen Dec 15 '15 at 19:46

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