class StatementEmpty in Drupal 8

Empty implementation of a database statement.

This class satisfies the requirements of being a database statement/result object, but does not actually contain data. It is useful when developers need to safely return an "empty" result set without connecting to an actual database. Calling code can then treat it the same as if it were an actual result set that happens to contain no records.

Hierarchy

• class \Drupal\Core\Database\StatementEmpty implements \Drupal\Core\Database\Iterator, StatementInterface

See also

\Drupal\search\SearchQuery

3 files declare their use of StatementEmpty

Connection.php in core/tests/fixtures/database_drivers/custom/fake/Connection.php

EmptyStatementTest.php in core/tests/Drupal/Tests/Core/Database/EmptyStatementTest.php

StubConnection.php in core/tests/Drupal/Tests/Core/Database/Stub/StubConnection.php

File

core/lib/Drupal/Core/Database/StatementEmpty.php, line 16

Namespace

Drupal\Core\Database

class StatementEmpty implements \Iterator, StatementInterface {

  /**
   * Is rowCount() execution allowed.
   *
   * @var bool
   */
  public $allowRowCount = FALSE;

  /**
   * {@inheritdoc}
   */
  public function execute($args = [], $options = []) {
    return FALSE;
  }

  /**
   * {@inheritdoc}
   */
  public function getQueryString() {
    return '';
  }

  /**
   * {@inheritdoc}
   */
  public function rowCount() {
    if ($this->allowRowCount) {
      return 0;
    }
    throw new RowCountException();
  }

  /**
   * {@inheritdoc}
   */
  public function setFetchMode($mode, $a1 = NULL, $a2 = []) {
  }

  /**
   * {@inheritdoc}
   */
  public function fetch($mode = NULL, $cursor_orientation = NULL, $cursor_offset = NULL) {
    return NULL;
  }

  /**
   * {@inheritdoc}
   */
  public function fetchField($index = 0) {
    return NULL;
  }

  /**
   * {@inheritdoc}
   */
  public function fetchObject() {
    return NULL;
  }

  /**
   * {@inheritdoc}
   */
  public function fetchAssoc() {
    return NULL;
  }

  /**
   * {@inheritdoc}
   */
  public function fetchAll($mode = NULL, $column_index = NULL, $constructor_arguments = NULL) {
    return [];
  }

  /**
   * {@inheritdoc}
   */
  public function fetchCol($index = 0) {
    return [];
  }

  /**
   * {@inheritdoc}
   */
  public function fetchAllKeyed($key_index = 0, $value_index = 1) {
    return [];
  }

  /**
   * {@inheritdoc}
   */
  public function fetchAllAssoc($key, $fetch = NULL) {
    return [];
  }

  /**
   * {@inheritdoc}
   */
  public function current() {
    return NULL;
  }

  /**
   * {@inheritdoc}
   */
  public function key() {
    return NULL;
  }

  /**
   * {@inheritdoc}
   */
  public function rewind() {

    // Nothing to do: our DatabaseStatement can't be rewound.
  }

  /**
   * {@inheritdoc}
   */
  public function next() {

    // Do nothing, since this is an always-empty implementation.
  }

  /**
   * {@inheritdoc}
   */
  public function valid() {
    return FALSE;
  }

}

Members

Name	Modifiers	Type	Description	Overrides
StatementEmpty::$allowRowCount	public	property	Is rowCount() execution allowed.
StatementEmpty::current	public	function
StatementEmpty::execute	public	function	Executes a prepared statement Overrides StatementInterface::execute
StatementEmpty::fetch	public	function	Fetches the next row from a result set. Overrides StatementInterface::fetch
StatementEmpty::fetchAll	public	function	Returns an array containing all of the result set rows. Overrides StatementInterface::fetchAll
StatementEmpty::fetchAllAssoc	public	function	Returns the result set as an associative array keyed by the given field. Overrides StatementInterface::fetchAllAssoc
StatementEmpty::fetchAllKeyed	public	function	Returns the entire result set as a single associative array. Overrides StatementInterface::fetchAllKeyed
StatementEmpty::fetchAssoc	public	function	Fetches the next row and returns it as an associative array. Overrides StatementInterface::fetchAssoc
StatementEmpty::fetchCol	public	function	Returns an entire single column of a result set as an indexed array. Overrides StatementInterface::fetchCol
StatementEmpty::fetchField	public	function	Returns a single field from the next record of a result set. Overrides StatementInterface::fetchField
StatementEmpty::fetchObject	public	function	Fetches the next row and returns it as an object. Overrides StatementInterface::fetchObject
StatementEmpty::getQueryString	public	function	Gets the query string of this statement. Overrides StatementInterface::getQueryString
StatementEmpty::key	public	function
StatementEmpty::next	public	function
StatementEmpty::rewind	public	function
StatementEmpty::rowCount	public	function	Returns the number of rows affected by the last SQL statement. Overrides StatementInterface::rowCount
StatementEmpty::setFetchMode	public	function	Sets the default fetch mode for this statement. Overrides StatementInterface::setFetchMode
StatementEmpty::valid	public	function