| public group ( mixed $keys, array $initial, MongoDB\BSON\Javascript | string $reduce, array $options = [] ) : array | ||
| $keys | mixed | fields to group by. If an array or non-code object is passed, it will be the key used to group results. If instance of [[\MongoDB\BSON\Javascript]] passed, it will be treated as a function that returns the key to group by. |
| $initial | array | Initial value of the aggregation counter object. |
| $reduce | MongoDB\BSON\Javascript | string | function that takes two arguments (the current document and the aggregation to this point) and does the aggregation. Argument will be automatically cast to [[\MongoDB\BSON\Javascript]]. |
| $options | array | optional parameters to the group command. Valid options include: - condition - criteria for including a document in the aggregation. - finalize - function called once per unique key that takes the final output of the reduce function. |
| return | array | the result of the aggregation. |
public function group($keys, $initial, $reduce, $options = [])
{
return $this->database->createCommand()->group($this->name, $keys, $initial, $reduce, $options);
}