mongodb\Collection mapReduce()

mapReduce() public method

Performs aggregation using MongoDB "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();

public string\|array mapReduce ( $map, $reduce, $out, $condition = [], $options = [] )
$map	\MongoDB\BSON\Javascript\|string	Function, which emits map data from collection. Argument will be automatically cast to \MongoDB\BSON\Javascript.
$reduce	\MongoDB\BSON\Javascript\|string	Function that takes two arguments (the map key and the map values) and does the aggregation. Argument will be automatically cast to \MongoDB\BSON\Javascript.
$out	string\|array	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.
$condition	array	Criteria for including a document in the aggregation.
$options	array	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: integer, the maximum number of documents to return in the collection. finalize: \MongoDB\BSON\Javascript\|string, 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	yii\mongodb\Exception	on failure.

Links:

http://www.yiiframework.com/doc-2.0/yii-mongodb-collection.html#mapReduce()-detail

doc_Yii

2016-10-30 17:07:40

Comments