Last updated: Fri, 20 May 2011

MongoDB::command

(PECL mongo >=0.9.2)

MongoDB::command — Execute a database command

Descripción

public array MongoDB::command ( array $command )

Almost everything that is not a CRUD operation can be done with a database command. Need to know the database version? There's a command for that. Need to do aggregation? There's a command for that. Need to turn up logging? You get the idea.

This method is identical to:


<?php

public function command($data) {
    return $this->selectCollection('$cmd')->findOne($data);
}

?>

Parámetros

command: The query to send.

Historial de cambios

Versión	Descripción
1.2.0	Added options parameter with a single option: timeout.

Valores devueltos

Returns database response.

Ejemplos

Example #1 MongoDB::command() "distinct" example

Finding all of the distinct values for a key.


<?php

$people = $db->people;

$people->insert(array("name" => "Joe", "age" => 4));
$people->insert(array("name" => "Sally", "age" => 22));
$people->insert(array("name" => "Dave", "age" => 22));
$people->insert(array("name" => "Molly", "age" => 87));

$ages = $db->command(array("distinct" => "people", "key" => "age"));

foreach ($ages['values'] as $age) {
    echo "$age\n";
}

?>

El resultado del ejemplo sería algo similar a:

4
22
87

Example #2 MongoDB::command() MapReduce example

Get all users with at least on "sale" event, and how many times each of these users has had a sale.


<?php

// sample event document
$events->insert(array("user_id" => $id, 
    "type" => $type, 
    "time" => new MongoDate(), 
    "desc" => $description));

// construct map and reduce functions
$map = new MongoCode("function() { emit(this.user_id,1); }");
$reduce = new MongoCode("function(k, vals) { ".
    "var sum = 0;".
    "for (var i in vals) {".
        "sum += vals[i];". 
    "}".
    "return sum; }");

$sales = $db->command(array(
    "mapreduce" => "events", 
    "map" => $map,
    "reduce" => $reduce,
    "query" => array("type" => "sale"),
    "out" => array("merge" => "eventCounts")));

$users = $db->selectCollection($sales['result'])->find();

foreach ($users as $user) {
    echo "{$user['_id']} had {$user['value']} sale(s).\n";
}

?>

El resultado del ejemplo sería algo similar a:

User 47cc67093475061e3d9536d2 had 3 sale(s).
User 49902cde5162504500b45c2c had 14 sale(s).
User 4af467e4fd543cce7b0ea8e2 had 1 sale(s).

Note: Using MongoCode

This example uses MongoCode, which can also take a scope argument. However, at the moment, MongoDB does not support using scopes in MapReduce. If you would like to use client-side variables in the MapReduce functions, you can add them to the global scope by using the optional scope field with the database command. See the » MapReduce documentation for more information.

Note: The out argument

Before 1.8.0, the out argument was optional. If you did not use it, MapReduce results would be written to a temporary collection, which would be deleted when your connection was closed. In 1.8.0+, the out argument is required. See the » MapReduce documentation for more information.

If you are going to be using MapReduce, Prajwal Tuladhar created an API for Mongo PHP users which provides a nicer interface than the bare command. You can download it from » Github and there is a » blog post on how to use it.

Ver también

MongoDB core docs on » database commands and on individual commands: » findAndModify, » getLastError, and » repair (dozens more exist, there are merely a few examples).

add a note User Contributed Notes MongoDB::command

roman dot drapeko at gmail dot com 16-Apr-2011 09:07


I tried to write MapReduce. Unfortunately, out => array('replace' => 'collName') did not work for me. Instead, the below code works





<?php


$mongo->command(array(


     'mapreduce' => 'events',


     'map' => $map,


     'reduce' => $reduce,


     'out' => 'mapReduceEventStats'


));


?>

Min He 21-Jul-2010 11:31


rename a collection: 





<?php


$m = new Mongo();


$adminDB = $m->admin; //require admin priviledge





//rename collection 'colA' in db 'yourdbA' to collection 'colB' in another db 'yourdbB'





$res = $adminDB->command(array(


    "renameCollection" => "yourdbA.colA",


    "to" => "yourdbB.colB"


));





var_dump($res);


?>

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