class DbtngExampleRepository in Examples for Developers 8

Repository for database-related helper methods for our example.

This repository is a service named 'dbtng_example.repository'. You can see how the service is defined in dbtng_example/dbtng_example.services.yml.

For projects where there are many specialized queries, it can be useful to group them into 'repositories' of queries. We can also architect this repository to be a service, so that it gathers the database connections it needs. This way other classes which use the repository don't need to concern themselves with database connections, only with business logic.

This repository demonstrates basic CRUD behaviors, and also has an advanced query which performs a join with the user table.

Hierarchy

• class \Drupal\dbtng_example\DbtngExampleRepository uses MessengerTrait, StringTranslationTrait

Related topics

Example: Database (DBTNG)

Database examples, including DBTNG.

3 files declare their use of DbtngExampleRepository

DbtngExampleAddForm.php in dbtng_example/src/Form/DbtngExampleAddForm.php

DbtngExampleController.php in dbtng_example/src/Controller/DbtngExampleController.php

DbtngExampleUpdateForm.php in dbtng_example/src/Form/DbtngExampleUpdateForm.php

1 string reference to 'DbtngExampleRepository'

dbtng_example.services.yml in dbtng_example/dbtng_example.services.yml

dbtng_example/dbtng_example.services.yml

1 service uses DbtngExampleRepository

dbtng_example.repository in dbtng_example/dbtng_example.services.yml

Drupal\dbtng_example\DbtngExampleRepository

File

dbtng_example/src/DbtngExampleRepository.php, line 28

Namespace

Drupal\dbtng_example

class DbtngExampleRepository {
  use MessengerTrait;
  use StringTranslationTrait;

  /**
   * The database connection.
   *
   * @var \Drupal\Core\Database\Connection
   */
  protected $connection;

  /**
   * Construct a repository object.
   *
   * @param \Drupal\Core\Database\Connection $connection
   *   The database connection.
   * @param \Drupal\Core\StringTranslation\TranslationInterface $translation
   *   The translation service.
   * @param \Drupal\Core\Messenger\MessengerInterface $messenger
   *   The messenger service.
   */
  public function __construct(Connection $connection, TranslationInterface $translation, MessengerInterface $messenger) {
    $this->connection = $connection;
    $this
      ->setStringTranslation($translation);
    $this
      ->setMessenger($messenger);
  }

  /**
   * Save an entry in the database.
   *
   * Exception handling is shown in this example. It could be simplified
   * without the try/catch blocks, but since an insert will throw an exception
   * and terminate your application if the exception is not handled, it is best
   * to employ try/catch.
   *
   * @param array $entry
   *   An array containing all the fields of the database record.
   *
   * @return int
   *   The number of updated rows.
   *
   * @throws \Exception
   *   When the database insert fails.
   */
  public function insert(array $entry) {
    try {
      $return_value = $this->connection
        ->insert('dbtng_example')
        ->fields($entry)
        ->execute();
    } catch (\Exception $e) {
      $this
        ->messenger()
        ->addMessage($this
        ->t('Insert failed. Message = %message', [
        '%message' => $e
          ->getMessage(),
      ]), 'error');
    }
    return $return_value ?? NULL;
  }

  /**
   * Update an entry in the database.
   *
   * @param array $entry
   *   An array containing all the fields of the item to be updated.
   *
   * @return int
   *   The number of updated rows.
   */
  public function update(array $entry) {
    try {

      // Connection->update()...->execute() returns the number of rows updated.
      $count = $this->connection
        ->update('dbtng_example')
        ->fields($entry)
        ->condition('pid', $entry['pid'])
        ->execute();
    } catch (\Exception $e) {
      $this
        ->messenger()
        ->addMessage($this
        ->t('Update failed. Message = %message, query= %query', [
        '%message' => $e
          ->getMessage(),
        '%query' => $e->query_string,
      ]), 'error');
    }
    return $count ?? 0;
  }

  /**
   * Delete an entry from the database.
   *
   * @param array $entry
   *   An array containing at least the person identifier 'pid' element of the
   *   entry to delete.
   *
   * @see Drupal\Core\Database\Connection::delete()
   */
  public function delete(array $entry) {
    $this->connection
      ->delete('dbtng_example')
      ->condition('pid', $entry['pid'])
      ->execute();
  }

  /**
   * Read from the database using a filter array.
   *
   * The standard function to perform reads for static queries is
   * Connection::query().
   *
   * Connection::query() uses an SQL query with placeholders and arguments as
   * parameters.
   *
   * Drupal DBTNG provides an abstracted interface that will work with a wide
   * variety of database engines.
   *
   * The following is a query which uses a string literal SQL query. The
   * placeholders will be substituted with the values in the array. Placeholders
   * are marked with a colon ':'. Table names are marked with braces, so that
   * Drupal's' multisite feature can add prefixes as needed.
   *
   * @code
   *   // SELECT * FROM {dbtng_example} WHERE uid = 0 AND name = 'John'
   *   \Drupal::database()->query(
   *     "SELECT * FROM {dbtng_example} WHERE uid = :uid and name = :name",
   *     [':uid' => 0, ':name' => 'John']
   *   )->execute();
   * @endcode
   *
   * For more dynamic queries, Drupal provides Connection::select() API method,
   * so there are several ways to perform the same SQL query. See the
   * @link http://drupal.org/node/310075 handbook page on dynamic queries. @endlink
   * @code
   *   // SELECT * FROM {dbtng_example} WHERE uid = 0 AND name = 'John'
   *   \Drupal::database()->select('dbtng_example')
   *     ->fields('dbtng_example')
   *     ->condition('uid', 0)
   *     ->condition('name', 'John')
   *     ->execute();
   * @endcode
   *
   * Here is select() with named placeholders:
   * @code
   *   // SELECT * FROM {dbtng_example} WHERE uid = 0 AND name = 'John'
   *   $arguments = array(':name' => 'John', ':uid' => 0);
   *   \Drupal::database()->select('dbtng_example')
   *     ->fields('dbtng_example')
   *     ->where('uid = :uid AND name = :name', $arguments)
   *     ->execute();
   * @endcode
   *
   * Conditions are stacked and evaluated as AND and OR depending on the type of
   * query. For more information, read the conditional queries handbook page at:
   * http://drupal.org/node/310086
   *
   * The condition argument is an 'equal' evaluation by default, but this can be
   * altered:
   * @code
   *   // SELECT * FROM {dbtng_example} WHERE age > 18
   *   \Drupal::database()->select('dbtng_example')
   *     ->fields('dbtng_example')
   *     ->condition('age', 18, '>')
   *     ->execute();
   * @endcode
   *
   * @param array $entry
   *   An array containing all the fields used to search the entries in the
   *   table.
   *
   * @return object
   *   An object containing the loaded entries if found.
   *
   * @see Drupal\Core\Database\Connection::select()
   */
  public function load(array $entry = []) {

    // Read all the fields from the dbtng_example table.
    $select = $this->connection
      ->select('dbtng_example')
      ->fields('dbtng_example');

    // Add each field and value as a condition to this query.
    foreach ($entry as $field => $value) {
      $select
        ->condition($field, $value);
    }

    // Return the result in object format.
    return $select
      ->execute()
      ->fetchAll();
  }

  /**
   * Load dbtng_example records joined with user records.
   *
   * DBTNG also helps processing queries that return several rows, providing the
   * found objects in the same query execution call.
   *
   * This function queries the database using a JOIN between users table and the
   * example entries, to provide the username that created the entry, and
   * creates a table with the results, processing each row.
   *
   * SELECT
   *  e.pid as pid, e.name as name, e.surname as surname, e.age as age
   *  u.name as username
   * FROM
   *  {dbtng_example} e
   * JOIN
   *  users u ON e.uid = u.uid
   * WHERE
   *  e.name = 'John' AND e.age > 18
   *
   * @see Drupal\Core\Database\Connection::select()
   * @see http://drupal.org/node/310075
   */
  public function advancedLoad() {

    // Get a select query for our dbtng_example table. We supply an alias of e
    // (for 'example').
    $select = $this->connection
      ->select('dbtng_example', 'e');

    // Join the users table, so we can get the entry creator's username.
    $select
      ->join('users_field_data', 'u', 'e.uid = u.uid');

    // Select these specific fields for the output.
    $select
      ->addField('e', 'pid');
    $select
      ->addField('u', 'name', 'username');
    $select
      ->addField('e', 'name');
    $select
      ->addField('e', 'surname');
    $select
      ->addField('e', 'age');

    // Filter only persons named "John".
    $select
      ->condition('e.name', 'John');

    // Filter only persons older than 18 years.
    $select
      ->condition('e.age', 18, '>');

    // Make sure we only get items 0-49, for scalability reasons.
    $select
      ->range(0, 50);
    $entries = $select
      ->execute()
      ->fetchAll(\PDO::FETCH_ASSOC);
    return $entries;
  }

}

Members

Name	Modifiers	Type	Description	Overrides
DbtngExampleRepository::$connection	protected	property	The database connection.
DbtngExampleRepository::advancedLoad	public	function	Load dbtng_example records joined with user records.
DbtngExampleRepository::delete	public	function	Delete an entry from the database.
DbtngExampleRepository::insert	public	function	Save an entry in the database.
DbtngExampleRepository::load	public	function	Read from the database using a filter array.
DbtngExampleRepository::update	public	function	Update an entry in the database.
DbtngExampleRepository::__construct	public	function	Construct a repository object.
MessengerTrait::$messenger	protected	property	The messenger.	29
MessengerTrait::messenger	public	function	Gets the messenger.	29
MessengerTrait::setMessenger	public	function	Sets the messenger.
StringTranslationTrait::$stringTranslation	protected	property	The string translation service.	1
StringTranslationTrait::formatPlural	protected	function	Formats a string containing a count of items.
StringTranslationTrait::getNumberOfPlurals	protected	function	Returns the number of plurals supported by a given language.
StringTranslationTrait::getStringTranslation	protected	function	Gets the string translation service.
StringTranslationTrait::setStringTranslation	public	function	Sets the string translation service to use.	2
StringTranslationTrait::t	protected	function	Translates a string to the current language or to a given language.