Merge pull request #15353 from totten/master-api4-header

[civicrm-core.git] / Civi / Api4 / Generic / BasicGetAction.php

<?php

/*
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 | CiviCRM version 5                                                  |
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 | Copyright CiviCRM LLC (c) 2004-2019                                |
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 | This file is a part of CiviCRM.                                    |
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 | CiviCRM is free software; you can copy, modify, and distribute it  |
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 | Version 3, 19 November 2007 and the CiviCRM Licensing Exception.   |
 |                                                                    |
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 | See the GNU Affero General Public License for more details.        |
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 */

/**
 *
 * @package CRM
 * @copyright CiviCRM LLC (c) 2004-2019
 * $Id$
 *
 */


namespace Civi\Api4\Generic;

use Civi\API\Exception\NotImplementedException;

/**
 * Retrieve items based on criteria specified in the 'where' param.
 *
 * Use the 'select' param to determine which fields are returned, defaults to *.
 */
class BasicGetAction extends AbstractGetAction {
  use Traits\ArrayQueryActionTrait;

  /**
   * @var callable
   *
   * Function(BasicGetAction $thisAction) => array<array>
   */
  private $getter;

  /**
   * Basic Get constructor.
   *
   * @param string $entityName
   * @param string $actionName
   * @param callable $getter
   */
  public function __construct($entityName, $actionName, $getter = NULL) {
    parent::__construct($entityName, $actionName);
    $this->getter = $getter;
  }

  /**
   * Fetch results from the getter then apply filter/sort/select/limit.
   *
   * @param \Civi\Api4\Generic\Result $result
   */
  public function _run(Result $result) {
    $this->setDefaultWhereClause();
    $values = $this->getRecords();
    $result->exchangeArray($this->queryArray($values));
  }

  /**
   * This Basic Get class is a general-purpose api for non-DAO-based entities.
   *
   * Useful for fetching records from files or other places.
   * You can specify any php function to retrieve the records, and this class will
   * automatically filter, sort, select & limit the raw data from your callback.
   *
   * You can implement this action in one of two ways:
   * 1. Use this class directly by passing a callable ($getter) to the constructor.
   * 2. Extend this class and override this function.
   *
   * Either way, this function should return an array of arrays, each representing one retrieved object.
   *
   * The simplest thing for your getter function to do is return every full record
   * and allow this class to automatically do the sorting and filtering.
   *
   * Sometimes however that may not be practical for performance reasons.
   * To optimize your getter, it can use the following helpers from $this:
   *
   * Use this->_itemsToGet() to match records to field values in the WHERE clause.
   * Note the WHERE clause can potentially be very complex and it is not recommended
   * to parse $this->where yourself.
   *
   * Use $this->_isFieldSelected() to check if a field value is called for - useful
   * if loading the field involves expensive calculations.
   *
   * Be careful not to make assumptions, e.g. if LIMIT 100 is specified and your getter "helpfully" truncates the list
   * at 100 without accounting for WHERE, ORDER BY and LIMIT clauses, the final filtered result may be very incorrect.
   *
   * @return array
   * @throws \Civi\API\Exception\NotImplementedException
   */
  protected function getRecords() {
    if (is_callable($this->getter)) {
      return call_user_func($this->getter, $this);
    }
    throw new NotImplementedException('Getter function not found for api4 ' . $this->getEntityName() . '::' . $this->getActionName());
  }

}