php-doc-en/reference/mongo/mongodb/command.xml

<?xml version="1.0" encoding="utf-8"?>

<!-- $Revision$ -->
<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>
   and on individual commands: 
   <link xlink:href="&url.mongodb.dochub.findandmodify;">findAndModify</link>, 
   <link xlink:href="&url.mongodb.dochub.getlasterror;">getLastError</link>, and 
   <link xlink:href="&url.mongodb.dochub.repair;">repair</link> (dozens more
   exist, there are merely a few examples).
  </para>
 </refsect1>
</refentry>
<!-- Keep this comment at the end of the file
Local variables:
mode: sgml
sgml-omittag:t
sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
sgml-indent-data:t
sgml-parent-document:nil
sgml-default-dtd-file:"~/.phpdoc/manual.ced"
sgml-exposed-tags:nil
sgml-local-catalogs:nil
sgml-local-ecat-files:nil
End:
vim600: syn=xml fen fdm=syntax fdl=2 si
vim: et tw=78 syn=sgml
vi: ts=1 sw=1
-->