class PagerSelectExtender

Query extender for pager queries.

This is the "default" pager mechanism. It creates a paged query with a fixed number of entries per page.

Hierarchy

Expanded class hierarchy of PagerSelectExtender

1 file declares its use of PagerSelectExtender
QueryBase.php in drupal/core/lib/Drupal/Core/Entity/Query/QueryBase.php
Definition of Drupal\Core\Entity\Query\QueryBase.

File

drupal/core/lib/Drupal/Core/Database/Query/PagerSelectExtender.php, line 20
Definition of Drupal\Core\Database\Query\PagerSelectExtender

Namespace

Drupal\Core\Database\Query
View source
class PagerSelectExtender extends SelectExtender {

  /**
   * The highest element we've autogenerated so far.
   *
   * @var int
   */
  static $maxElement = 0;

  /**
   * The number of elements per page to allow.
   *
   * @var int
   */
  protected $limit = 10;

  /**
   * The unique ID of this pager on this page.
   *
   * @var int
   */
  protected $element = NULL;

  /**
   * The count query that will be used for this pager.
   *
   * @var SelectQueryInterface
   */
  protected $customCountQuery = FALSE;
  public function __construct(SelectInterface $query, Connection $connection) {
    parent::__construct($query, $connection);

    // Add pager tag. Do this here to ensure that it is always added before
    // preExecute() is called.
    $this
      ->addTag('pager');
  }

  /**
   * Override the execute method.
   *
   * Before we run the query, we need to add pager-based range() instructions
   * to it.
   */
  public function execute() {

    // Add convenience tag to mark that this is an extended query. We have to
    // do this in the constructor to ensure that it is set before preExecute()
    // gets called.
    if (!$this
      ->preExecute($this)) {
      return NULL;
    }

    // A NULL limit is the "kill switch" for pager queries.
    if (empty($this->limit)) {
      return;
    }
    $this
      ->ensureElement();
    $total_items = $this
      ->getCountQuery()
      ->execute()
      ->fetchField();
    $current_page = pager_default_initialize($total_items, $this->limit, $this->element);
    $this
      ->range($current_page * $this->limit, $this->limit);

    // Now that we've added our pager-based range instructions, run the query normally.
    return $this->query
      ->execute();
  }

  /**
   * Ensure that there is an element associated with this query.
   * If an element was not specified previously, then the value of the
   * $maxElement counter is taken, after which the counter is incremented.
   *
   * After running this method, access $this->element to get the element for this
   * query.
   */
  protected function ensureElement() {
    if (!isset($this->element)) {
      $this->element = self::$maxElement++;
    }
  }

  /**
   * Specify the count query object to use for this pager.
   *
   * You will rarely need to specify a count query directly.  If not specified,
   * one is generated off of the pager query itself.
   *
   * @param SelectQueryInterface $query
   *   The count query object.  It must return a single row with a single column,
   *   which is the total number of records.
   */
  public function setCountQuery(SelectInterface $query) {
    $this->customCountQuery = $query;
  }

  /**
   * Retrieve the count query for this pager.
   *
   * The count query may be specified manually or, by default, taken from the
   * query we are extending.
   *
   * @return SelectQueryInterface
   *   A count query object.
   */
  public function getCountQuery() {
    if ($this->customCountQuery) {
      return $this->customCountQuery;
    }
    else {
      return $this->query
        ->countQuery();
    }
  }

  /**
   * Specify the maximum number of elements per page for this query.
   *
   * The default if not specified is 10 items per page.
   *
   * @param $limit
   *   An integer specifying the number of elements per page.  If passed a false
   *   value (FALSE, 0, NULL), the pager is disabled.
   */
  public function limit($limit = 10) {
    $this->limit = $limit;
    return $this;
  }

  /**
   * Specify the element ID for this pager query.
   *
   * The element is used to differentiate different pager queries on the same
   * page so that they may be operated independently.  If you do not specify an
   * element, every pager query on the page will get a unique element.  If for
   * whatever reason you want to explicitly define an element for a given query,
   * you may do so here.
   *
   * Setting the element here also increments the static $maxElement counter,
   * which is used for determining the $element when there's none specified.
   *
   * Note that no collision detection is done when setting an element ID
   * explicitly, so it is possible for two pagers to end up using the same ID
   * if both are set explicitly.
   *
   * @param $element
   */
  public function element($element) {
    $this->element = $element;
    if ($element >= self::$maxElement) {
      self::$maxElement = $element + 1;
    }
    return $this;
  }

}

Members

Namesort descending Modifiers Type Description Overrides
PagerSelectExtender::$customCountQuery protected property The count query that will be used for this pager.
PagerSelectExtender::$element protected property The unique ID of this pager on this page.
PagerSelectExtender::$limit protected property The number of elements per page to allow.
PagerSelectExtender::$maxElement static property The highest element we've autogenerated so far.
PagerSelectExtender::element public function Specify the element ID for this pager query.
PagerSelectExtender::ensureElement protected function Ensure that there is an element associated with this query. If an element was not specified previously, then the value of the $maxElement counter is taken, after which the counter is incremented.
PagerSelectExtender::execute public function Override the execute method. Overrides SelectExtender::execute
PagerSelectExtender::getCountQuery public function Retrieve the count query for this pager.
PagerSelectExtender::limit public function Specify the maximum number of elements per page for this query.
PagerSelectExtender::setCountQuery public function Specify the count query object to use for this pager.
PagerSelectExtender::__construct public function Overrides SelectExtender::__construct
SelectExtender::$connection protected property The connection object on which to run this query.
SelectExtender::$placeholder protected property The placeholder counter.
SelectExtender::$query protected property The Select query object we are extending/decorating.
SelectExtender::$uniqueIdentifier protected property A unique identifier for this query object.
SelectExtender::addExpression public function Adds an expression to the list of "fields" to be SELECTed. Overrides SelectInterface::addExpression
SelectExtender::addField public function Adds a field to the list to be SELECTed. Overrides SelectInterface::addField
SelectExtender::addJoin public function Join against another table in the database. Overrides SelectInterface::addJoin
SelectExtender::addMetaData public function Adds additional metadata to the query. Overrides AlterableInterface::addMetaData
SelectExtender::addTag public function Adds a tag to a query. Overrides AlterableInterface::addTag
SelectExtender::arguments public function Gets a complete list of all values to insert into the prepared statement. Overrides ConditionInterface::arguments
SelectExtender::compile public function Compiles the saved conditions for later retrieval. Overrides ConditionInterface::compile
SelectExtender::compiled public function Check whether a condition has been previously compiled. Overrides ConditionInterface::compiled
SelectExtender::condition public function Helper function: builds the most common conditional clauses. Overrides ConditionInterface::condition
SelectExtender::conditions public function Gets a complete list of all conditions in this conditional clause. Overrides ConditionInterface::conditions 1
SelectExtender::countQuery public function Get the equivalent COUNT query of this query as a new query object. Overrides SelectInterface::countQuery 1
SelectExtender::distinct public function Sets this query to be DISTINCT. Overrides SelectInterface::distinct
SelectExtender::exists public function Sets a condition that the specified subquery returns values. Overrides ConditionInterface::exists
SelectExtender::extend public function Enhance this object by wrapping it in an extender object. Overrides ExtendableInterface::extend
SelectExtender::fields public function Add multiple fields from the same table to be SELECTed. Overrides SelectInterface::fields
SelectExtender::forUpdate public function Add FOR UPDATE to the query. Overrides SelectInterface::forUpdate
SelectExtender::getArguments public function Compiles and returns an associative array of the arguments for this prepared statement. Overrides SelectInterface::getArguments
SelectExtender::getExpressions public function Returns a reference to the expressions array for this query. Overrides SelectInterface::getExpressions
SelectExtender::getFields public function Returns a reference to the fields array for this query. Overrides SelectInterface::getFields
SelectExtender::getGroupBy public function Returns a reference to the group-by array for this query. Overrides SelectInterface::getGroupBy
SelectExtender::getMetaData public function Retrieves a given piece of metadata. Overrides AlterableInterface::getMetaData
SelectExtender::getOrderBy public function Returns a reference to the order by array for this query. Overrides SelectInterface::getOrderBy
SelectExtender::getTables public function Returns a reference to the tables array for this query. Overrides SelectInterface::getTables
SelectExtender::getUnion public function Returns a reference to the union queries for this query. This include queries for UNION, UNION ALL, and UNION DISTINCT. Overrides SelectInterface::getUnion
SelectExtender::groupBy public function Groups the result set by the specified field. Overrides SelectInterface::groupBy
SelectExtender::hasAllTags public function Determines if a given query has all specified tags. Overrides AlterableInterface::hasAllTags
SelectExtender::hasAnyTag public function Determines if a given query has any specified tag. Overrides AlterableInterface::hasAnyTag
SelectExtender::hasTag public function Determines if a given query has a given tag. Overrides AlterableInterface::hasTag
SelectExtender::having public function
SelectExtender::havingArguments public function
SelectExtender::havingCompile public function
SelectExtender::havingCondition public function Helper function to build most common HAVING conditional clauses. Overrides SelectInterface::havingCondition
SelectExtender::havingConditions public function
SelectExtender::innerJoin public function Inner Join against another table in the database. Overrides SelectInterface::innerJoin
SelectExtender::isNotNull function Sets a condition that the specified field be NOT NULL. Overrides ConditionInterface::isNotNull
SelectExtender::isNull function Sets a condition that the specified field be NULL. Overrides ConditionInterface::isNull
SelectExtender::isPrepared public function Indicates if preExecute() has already been called on that object. Overrides SelectInterface::isPrepared
SelectExtender::join public function Default Join against another table in the database. Overrides SelectInterface::join
SelectExtender::leftJoin public function Left Outer Join against another table in the database. Overrides SelectInterface::leftJoin
SelectExtender::nextPlaceholder public function Implements Drupal\Core\Database\Query\PlaceholderInterface::nextPlaceholder(). Overrides PlaceholderInterface::nextPlaceholder
SelectExtender::notExists public function Sets a condition that the specified subquery returns no values. Overrides ConditionInterface::notExists
SelectExtender::orderBy public function Orders the result set by a given field. Overrides SelectInterface::orderBy
SelectExtender::orderRandom public function Orders the result set by a random value. Overrides SelectInterface::orderRandom
SelectExtender::preExecute public function Generic preparation and validation for a SELECT query. Overrides SelectInterface::preExecute
SelectExtender::range public function Restricts a query to a given range in the result set. Overrides SelectInterface::range
SelectExtender::rightJoin public function Right Outer Join against another table in the database. Overrides SelectInterface::rightJoin
SelectExtender::union public function Add another Select query to UNION to this one. Overrides SelectInterface::union
SelectExtender::uniqueIdentifier public function Implements Drupal\Core\Database\Query\PlaceholderInterface::uniqueIdentifier(). Overrides PlaceholderInterface::uniqueIdentifier
SelectExtender::where public function Adds an arbitrary WHERE clause to the query. Overrides ConditionInterface::where
SelectExtender::__call public function Magic override for undefined methods.
SelectExtender::__clone public function Clone magic method. Overrides SelectInterface::__clone
SelectExtender::__toString public function