/**
* Performs aggregation using Mongo "map reduce" mechanism.
* Note: this function will not return the aggregation result, instead it will
* write it inside the another Mongo collection specified by "out" parameter.
* For example:
*
* ~~~
* $customerCollection = Yii::$app->mongo->getCollection('customer');
* $resultCollectionName = $customerCollection->mapReduce(
* 'function () {emit(this.status, this.amount)}',
* 'function (key, values) {return Array.sum(values)}',
* 'mapReduceOut',
* ['status' => 3]
* );
* $query = new Query();
* $results = $query->from($resultCollectionName)->all();
* ~~~
*
* @param \MongoCode|string $map function, which emits map data from collection.
* Argument will be automatically cast to [[\MongoCode]].
* @param \MongoCode|string $reduce function that takes two arguments (the map key
* and the map values) and does the aggregation.
* Argument will be automatically cast to [[\MongoCode]].
* @param string|array $out output collection name. It could be a string for simple output
* ('outputCollection'), or an array for parametrized output (['merge' => 'outputCollection']).
* You can pass ['inline' => true] to fetch the result at once without temporary collection usage.
* @param array $condition criteria for including a document in the aggregation.
* @param array $options additional optional parameters to the mapReduce command. Valid options include:
* - sort - array - key to sort the input documents. The sort key must be in an existing index for this collection.
* - limit - the maximum number of documents to return in the collection.
* - finalize - function, which follows the reduce method and modifies the output.
* - scope - array - specifies global variables that are accessible in the map, reduce and finalize functions.
* - jsMode - boolean -Specifies whether to convert intermediate data into BSON format between the execution of the map and reduce functions.
* - verbose - boolean - specifies whether to include the timing information in the result information.
* @return string|array the map reduce output collection name or output results.
* @throws Exception on failure.
*/
public function mapReduce($map, $reduce, $out, $condition = [], $options = [])
{
$command = ['mapReduce' => $this->getName(), 'map' => $map, 'reduce' => $reduce, 'out' => $out];
if (!empty($condition)) {
$command['query'] = $this->buildCondition($condition);
}
$command = new \MongoDB\Driver\Command(array_merge($command, $options));
$token = $this->composeLogToken('mapReduce', [$map, $reduce, $out]);
Yii::info($token, __METHOD__);
try {
Yii::beginProfile($token, __METHOD__);
$result = $this->mongoManager->executeCommand($this->dbName, $command);
$this->tryResultError($result);
Yii::endProfile($token, __METHOD__);
$row = MongoHelper::cursorFirst($result);
return isset($row['result']) ? $row['result'] : $row['results'];
} catch (\Exception $e) {
Yii::endProfile($token, __METHOD__);
throw new Exception($e->getMessage(), (int) $e->getCode(), $e);
}
}
/**
* Executes Mongo command.
* @param array $command command specification.
* @param array $options options in format: "name" => "value"
* @return array database response.
* @throws Exception on failure.
*/
public function executeCommand($command, $options = [])
{
$token = $this->getName() . '.$cmd(' . Json::encode($command) . ', ' . Json::encode($options) . ')';
Yii::info($token, __METHOD__);
try {
Yii::beginProfile($token, __METHOD__);
$command = new \MongoDB\Driver\Command($command);
$result = $this->mongoManager->executeCommand($this->dbName, $command);
$this->tryResultError($result);
Yii::endProfile($token, __METHOD__);
return MongoHelper::cursorFirst($result);
} catch (\Exception $e) {
Yii::endProfile($token, __METHOD__);
throw new Exception($e->getMessage(), (int) $e->getCode(), $e);
}
}
/**
* @param \MongoDB\Driver\Cursor $cursor Mongo cursor instance to fetch data from.
* @param boolean $all whether to fetch all rows or only first one.
* @param string|callable $indexBy value to index by.
* @return array|boolean result.
* @see Query::fetchRows()
*/
protected function fetchRowsInternal($cursor, $all, $indexBy)
{
if ($all) {
$rows = [];
foreach ($cursor as $row) {
$rows[] = MongoHelper::resultToArray($row);
}
return $rows;
} else {
foreach ($cursor as $row) {
break;
}
return isset($row) ? MongoHelper::resultToArray($row) : false;
}
}
