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<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision: 296627 $ -->
<refentry xml:id="mongodb.command" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
<refnamediv>
<refname>MongoDB::command</refname>
<refpurpose>Execute a database command</refpurpose>
</refnamediv>
<refsect1 role="description">
&reftitle.description;
<methodsynopsis>
<modifier>public</modifier> <type>array</type><methodname>MongoDB::command</methodname>
<methodparam><type>array</type><parameter>data</parameter></methodparam>
</methodsynopsis>
<para>
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.
</para>
<para>
This method is identical to the function:
<programlisting role="php">
<![CDATA[
<?php
public function command($data) {
return $this->selectCollection('$cmd')->findOne($data);
}
?>
]]>
</programlisting>
</para>
</refsect1>
<refsect1 role="parameters">
&reftitle.parameters;
<para>
<variablelist>
<varlistentry>
<term>
<parameter>data</parameter>
</term>
<listitem>
<para>
The query to send.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
<refsect1 role="returnvalues">
&reftitle.returnvalues;
<para>
Returns database response.
</para>
</refsect1>
<refsect1 role="examples">
&reftitle.examples;
<example>
<title><function>MongoDB::command</function> "distinct" example</title>
<para>
Finding all of the distinct values for a key.
</para>
<programlisting role="php">
<![CDATA[
<?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";
}
?>
]]>
</programlisting>
&example.outputs.similar;
<screen>
4
22
87
</screen>
</example>
<example>
<title><function>MongoDB::command</function> MapReduce example</title>
<para>
Get all users with at least on "sale" event, and how many times each
of these users has had a sale.
</para>
<programlisting role="php">
<![CDATA[
<?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")));
$users = $db->selectCollection($sales['result'])->find();
foreach ($users as $user) {
echo "{$user['_id']} had {$user['value']} sale(s).\n";
}
?>
]]>
</programlisting>
&example.outputs.similar;
<screen>
User 47cc67093475061e3d9536d2 had 3 sale(s).
User 49902cde5162504500b45c2c had 14 sale(s).
User 4af467e4fd543cce7b0ea8e2 had 1 sale(s).
</screen>
<note>
<title>Using <classname>MongoCode</classname></title>
<para>
This example uses <classname>MongoCode</classname>, 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
<link xlink:href="&url.mongodb.dochub.mapreduce;">MapReduce</link> for more
information.
</para>
</note>
<para>
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
<link xlink:href="&url.mongodb.mapreduceapi;">Github</link>
and there is a
<link xlink:href="&url.mongodb.mapreduceapi.blog;">blog post</link>
on how to use it.
</para>
</example>
</refsect1>
<refsect1 role="seealso">
&reftitle.seealso;
<para>
MongoDB core docs on <link xlink:href="&url.mongodb.dochub.commands;">database commands</link>.
</para>
</refsect1>
</refentry>
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