php-doc-en/reference/mongo/mongocollection/aggregatecursor.xml

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<refentry xml:id="mongocollection.aggregatecursor" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
 <refnamediv>
  <refname>MongoCollection::aggregateCursor</refname>
  <refpurpose>Execute an aggregation pipeline command and retrieve results through a cursor</refpurpose>
 </refnamediv>
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <modifier>public</modifier> <type>MongoCommandCursor</type><methodname>MongoCollection::aggregateCursor</methodname>
   <methodparam><type>array</type><parameter>command</parameter></methodparam>
   <methodparam choice="opt"><type>array</type><parameter>options</parameter></methodparam>
  </methodsynopsis>
  <para>
   With this method you can execute Aggregation Framework pipelines and
   retrieve the results through a cursor, instead of getting just one document
   back as you would with <methodname>MongoCollection::aggregate</methodname>.
   This method returns a <classname>MongoCommandCursor</classname> object.
   This cursor object implements the <classname>Iterator</classname> interface
   just like the <classname>MongoCursor</classname> objects that are returned
   by the <methodname>MongoCollection::find</methodname> method.
  </para>
  <note>
   <simpara>
    The resulting <classname>MongoCommandCursor</classname> will inherit this
    collection's read preference.
    <methodname>MongoCommandCursor::setReadPreference</methodname> may be used
    to change the read preference before iterating on the cursor.
   </simpara>
  </note>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term>
      <parameter>pipeline</parameter>
     </term>
     <listitem>
      <para>
       The Aggregation Framework pipeline to execute.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>options</parameter></term>
     <listitem>
      <para>Options for the aggregation command. Valid options include:</para>
      <itemizedlist>
       <listitem>
        <para><literal>"allowDiskUse"</literal></para>
        <para>Allow aggregation stages to write to temporary files</para>
       </listitem>
       <listitem>
        <para><literal>"cursor"</literal></para>
        <para>
         It is possible to configure how many initial documents the server
         should return with the first result set. The default initial batch size
         is <literal>101</literal>. You can change it by adding the
         <literal>batchSize</literal> option:
        </para>
        <programlisting role="php">
<![CDATA[
<?php
$collection->aggregateCursor( 
    $pipeline,
    [ "cursor" => [ "batchSize" => 4 ] ]
);
]]>
        </programlisting>
        <para>
         This option only configures the size of the first batch. To configure
         the size of future batches, please use the
         <methodname>MongoCommandCursor::batchSize</methodname> method on the
         returned <classname>MongoCommandCursor</classname> object.
        </para>
       </listitem>
       <listitem>
        <para><literal>"explain"</literal></para>
        <para>
         Return information on the processing of the pipeline. This option may
         cause the command to return a result document that is unsuitable for
         constructing a <classname>MongoCommandCursor</classname>. If you need
         to use this option, you should consider using
         <methodname>MongoCollection::aggregate</methodname>.
        </para>
       </listitem>
       &mongo.command.parameters.maxtimems;
      </itemizedlist>
     </listitem>
    </varlistentry>   
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;  
  <para>
   Returns a <classname>MongoCommandCursor</classname> object. Because this
   implements the <classname>Iterator</classname> interface you can 
   iterate over each of the results as returned by the command query. The
   <classname>MongoCommandCursor</classname> also implements the
   <classname>MongoCursorInterface</classname> interface which adds the
   <methodname>MongoCommandCursor::batchSize</methodname>,
   <methodname>MongoCommandCursor::dead</methodname>,
   <methodname>MongoCommandCursor::info</methodname> methods.
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <example>
   <title><function>MongoCollection::aggregateCursor</function> example</title>
   <para>
    Finding all of the distinct values for a key.
   </para>
   <programlisting role="php">
<![CDATA[
<?php
$m = new MongoClient;
$db = $m->test;
$people = $db->people;
$people->drop();

$people->insert(array("name" => "Joe", "points" => 4));
$people->insert(array("name" => "Molly", "points" => 43));
$people->insert(array("name" => "Sally", "points" => 22));
$people->insert(array("name" => "Joe", "points" => 22));
$people->insert(array("name" => "Molly", "points" => 87));

$ages = $people->aggregateCursor( [
        [ '$group' => [ '_id' => '$name', 'points' => [ '$sum' => '$points' ] ] ],
        [ '$sort' => [ 'points' => -1 ] ],
] );

foreach ($ages as $person) {
    echo "{$person['_id']}: {$person['points']}\n";
}

?>
]]>
   </programlisting>
   &example.outputs.similar;
   <screen>
Molly: 130
Joe: 26
Sally: 22
   </screen>
  </example>

  <example>
   <title><function>MongoCollection::aggregateCursor</function>
   example with different initial batch size</title>
   <para>
    Finding all of the distinct values for a key.
   </para>
   <programlisting role="php">
<![CDATA[
<?php
$m = new MongoClient;
$db = $m->test;
$people = $db->people;
$people->drop();

/* Insert some sample data */
$people->insert(array("name" => "Joe", "points" => 4));
$people->insert(array("name" => "Molly", "points" => 43));
$people->insert(array("name" => "Sally", "points" => 22));
$people->insert(array("name" => "Joe", "points" => 22));
$people->insert(array("name" => "Molly", "points" => 87));

/* Run the command cursor */
$ages = $people->aggregateCursor(
    [
        [ '$group' => [ '_id' => '$name', 'points' => [ '$sum' => '$points' ] ] ],
        [ '$sort' => [ 'points' => -1 ] ],
    ],
    [ "cursor" => [ "batchSize" => 4 ] ]
);

foreach ($ages as $person) {
    echo "{$person['_id']}: {$person['points']}\n";
}

?>
]]>
   </programlisting>
   &example.outputs.similar;
   <screen>
Molly: 130
Joe: 26
Sally: 22
   </screen>
  </example>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><methodname>MongoDB::command</methodname></member>
    <member><classname>MongoCommandCursor</classname></member>
    <member><methodname>MongoCommandCursor::batchSize</methodname></member>
    <member><methodname>MongoCollection::aggregate</methodname></member>
    <member>The MongoDB <link xlink:href="&url.mongodb.docs.aggregation;">aggregation framework</link></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>
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