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class PagerSelectExtender in Zircon Profile 8

Same name and namespace in other branches
  1. 8.0 core/lib/Drupal/Core/Database/Query/PagerSelectExtender.php \Drupal\Core\Database\Query\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.

When adding this extender along with other extenders, be sure to add PagerSelectExtender last, so that its range and count are based on the full query.

Hierarchy

Expanded class hierarchy of PagerSelectExtender

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

File

core/lib/Drupal/Core/Database/Query/PagerSelectExtender.php, line 22
Contains \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 \Drupal\Core\Database\Query\SelectInterface
   */
  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 \Drupal\Core\Database\Query\SelectInterface $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 \Drupal\Core\Database\Query\SelectInterface
   *   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 int|false $limit
   *   An integer specifying the number of elements per page. If passed a false
   *   value (FALSE, 0, NULL), the pager is disabled.
   */
  public function limit($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 $element
   *   Element ID that is used to differentiate different pager queries.
   */
  public function element($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::andConditionGroup public function Creates a new group of conditions ANDed together. Overrides ConditionInterface::andConditionGroup
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::conditionGroupFactory public function Creates an object holding a group of conditions. Overrides ConditionInterface::conditionGroupFactory
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::escapeField public function Escapes a field name string. Overrides SelectInterface::escapeField
SelectExtender::escapeLike public function Escapes characters that work as wildcard characters in a LIKE pattern. Overrides SelectInterface::escapeLike
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 Adds an arbitrary HAVING clause to the query. Overrides SelectInterface::having
SelectExtender::havingArguments public function Gets a list of all values to insert into the HAVING clause. Overrides SelectInterface::havingArguments
SelectExtender::havingCompile public function Compiles the HAVING clause for later retrieval. Overrides SelectInterface::havingCompile
SelectExtender::havingCondition public function Helper function to build most common HAVING conditional clauses. Overrides SelectInterface::havingCondition
SelectExtender::havingConditions public function Gets a list of all conditions in the HAVING clause. Overrides SelectInterface::havingConditions
SelectExtender::havingExists public function Sets a HAVING condition that the specified subquery returns values. Overrides SelectInterface::havingExists
SelectExtender::havingIsNotNull public function Sets a condition in the HAVING clause that the specified field be NOT NULL. Overrides SelectInterface::havingIsNotNull
SelectExtender::havingIsNull public function Sets a condition in the HAVING clause that the specified field be NULL. Overrides SelectInterface::havingIsNull
SelectExtender::havingNotExists public function Sets a HAVING condition that the specified subquery returns no values. Overrides SelectInterface::havingNotExists
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 Returns the next placeholder ID for the query. Overrides PlaceholderInterface::nextPlaceholder
SelectExtender::notExists public function Sets a condition that the specified subquery returns no values. Overrides ConditionInterface::notExists
SelectExtender::orConditionGroup public function Creates a new group of conditions ORed together. Overrides ConditionInterface::orConditionGroup
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 1
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 Returns a unique identifier for this object. 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 Returns a string representation of how the query will be executed in SQL. Overrides SelectInterface::__toString