<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <title>The MongoDB\Driver\Cursor class</title> </head> <body><div class="manualnavbar" style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="mongodb-driver-readconcern.isdefault.html">MongoDB\Driver\ReadConcern::isDefault</a></div> <div class="next" style="text-align: right; float: right;"><a href="mongodb-driver-cursor.construct.html">MongoDB\Driver\Cursor::__construct</a></div> <div class="up"><a href="book.mongodb.html">MongoDB\Driver</a></div> <div class="home"><a href="index.html">PHP Manual</a></div> </div><hr /><div id="class.mongodb-driver-cursor" class="reference"> <h1 class="title">The MongoDB\Driver\Cursor class</h1> <div class="partintro"><p class="verinfo">(mongodb >=1.0.0)</p> <div class="section" id="mongodb-driver-cursor.intro"> <h2 class="title">Introduction</h2> <p class="para"> The <strong class="classname">MongoDB\Driver\Cursor</strong> class encapsulates the results of a MongoDB command or query and may be returned by <span class="methodname"><a href="mongodb-driver-manager.executecommand.html" class="methodname">MongoDB\Driver\Manager::executeCommand()</a></span> or <span class="methodname"><a href="mongodb-driver-manager.executequery.html" class="methodname">MongoDB\Driver\Manager::executeQuery()</a></span>, respectively. </p> </div> <div class="section" id="mongodb-driver-cursor.synopsis"> <h2 class="title">Class synopsis</h2> <div class="classsynopsis"> <div class="ooclass"></div> <div class="classsynopsisinfo"> <span class="modifier">final</span> <span class="ooclass"> <strong class="classname">MongoDB\Driver\Cursor</strong> </span> <span class="oointerface">implements <span class="interfacename"><a href="class.traversable.html" class="interfacename">Traversable</a></span> </span> {</div> <div class="classsynopsisinfo classsynopsisinfo_comment">/* Methods */</div> <div class="methodsynopsis dc-description"> <span class="modifier">final</span> <span class="modifier">private</span> <span class="methodname"><a href="mongodb-driver-cursor.construct.html" class="methodname">__construct</a></span> ( <span class="methodparam">void</span> )</div> <div class="methodsynopsis dc-description"> <span class="modifier">final</span> <span class="modifier">public</span> <span class="type">MongoDB\Driver\CursorId</span> <span class="methodname"><a href="mongodb-driver-cursor.getid.html" class="methodname">getId</a></span> ( <span class="methodparam">void</span> )</div> <div class="methodsynopsis dc-description"> <span class="modifier">final</span> <span class="modifier">public</span> <span class="type">MongoDB\Driver\Server</span> <span class="methodname"><a href="mongodb-driver-cursor.getserver.html" class="methodname">getServer</a></span> ( <span class="methodparam">void</span> )</div> <div class="methodsynopsis dc-description"> <span class="modifier">final</span> <span class="modifier">public</span> <span class="type">bool</span> <span class="methodname"><a href="mongodb-driver-cursor.isdead.html" class="methodname">isDead</a></span> ( <span class="methodparam">void</span> )</div> <div class="methodsynopsis dc-description"> <span class="modifier">final</span> <span class="modifier">public</span> <span class="type">void</span> <span class="methodname"><a href="mongodb-driver-cursor.settypemap.html" class="methodname">setTypeMap</a></span> ( <span class="methodparam"><span class="type">array</span> <code class="parameter">$typemap</code></span> )</div> <div class="methodsynopsis dc-description"> <span class="modifier">final</span> <span class="modifier">public</span> <span class="type">array</span> <span class="methodname"><a href="mongodb-driver-cursor.toarray.html" class="methodname">toArray</a></span> ( <span class="methodparam">void</span> )</div> }</div> </div> <div class="section" id="mongodb-driver-cursor.examples"> <h2 class="title">Examples</h2> <div class="example" id="example-1722"> <p><strong>Example #1 Reading a result set</strong></p> <div class="example-contents"><p> <span class="methodname"><a href="mongodb-driver-manager.executecommand.html" class="methodname">MongoDB\Driver\Manager::executeCommand()</a></span> and <span class="methodname"><a href="mongodb-driver-manager.executequery.html" class="methodname">MongoDB\Driver\Manager::executeQuery()</a></span> both return their result(s) as a <strong class="classname">MongoDB\Driver\Cursor</strong> object. This object can be used to iterate over the result set of the command or query. </p></div> <div class="example-contents"><p> Because <strong class="classname">MongoDB\Driver\Cursor</strong> implements the <span class="interfacename"><a href="class.traversable.html" class="interfacename">Traversable</a></span> interface, you can simply iterate over the result set with <a href="control-structures.foreach.html" class="link"><em>foreach</em></a>. </p></div> <div class="example-contents"> <div class="phpcode"><code><span style="color: #000000"> <span style="color: #0000BB"><?php<br /><br />$manager </span><span style="color: #007700">= new </span><span style="color: #0000BB">MongoDB</span><span style="color: #007700">\</span><span style="color: #0000BB">Driver</span><span style="color: #007700">\</span><span style="color: #0000BB">Manager</span><span style="color: #007700">();<br /><br /></span><span style="color: #FF8000">/* Insert some documents so that our query returns information */<br /></span><span style="color: #0000BB">$bulkWrite </span><span style="color: #007700">= new </span><span style="color: #0000BB">MongoDB</span><span style="color: #007700">\</span><span style="color: #0000BB">Driver</span><span style="color: #007700">\</span><span style="color: #0000BB">BulkWrite</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$bulkWrite</span><span style="color: #007700">-></span><span style="color: #0000BB">insert</span><span style="color: #007700">([</span><span style="color: #DD0000">'name' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'Ceres'</span><span style="color: #007700">, </span><span style="color: #DD0000">'size' </span><span style="color: #007700">=> </span><span style="color: #0000BB">946</span><span style="color: #007700">, </span><span style="color: #DD0000">'distance' </span><span style="color: #007700">=> </span><span style="color: #0000BB">2.766</span><span style="color: #007700">]);<br /></span><span style="color: #0000BB">$bulkWrite</span><span style="color: #007700">-></span><span style="color: #0000BB">insert</span><span style="color: #007700">([</span><span style="color: #DD0000">'name' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'Vesta'</span><span style="color: #007700">, </span><span style="color: #DD0000">'size' </span><span style="color: #007700">=> </span><span style="color: #0000BB">525</span><span style="color: #007700">, </span><span style="color: #DD0000">'distance' </span><span style="color: #007700">=> </span><span style="color: #0000BB">2.362</span><span style="color: #007700">]);<br /></span><span style="color: #0000BB">$manager</span><span style="color: #007700">-></span><span style="color: #0000BB">executeBulkWrite</span><span style="color: #007700">(</span><span style="color: #DD0000">"test.asteroids"</span><span style="color: #007700">, </span><span style="color: #0000BB">$bulkWrite</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">/* Query for all the items in the collection */<br /></span><span style="color: #0000BB">$query </span><span style="color: #007700">= new </span><span style="color: #0000BB">MongoDB</span><span style="color: #007700">\</span><span style="color: #0000BB">Driver</span><span style="color: #007700">\</span><span style="color: #0000BB">Query</span><span style="color: #007700">( [] );<br /><br /></span><span style="color: #FF8000">/* Query the "asteroids" collection of the "test" database */<br /></span><span style="color: #0000BB">$cursor </span><span style="color: #007700">= </span><span style="color: #0000BB">$manager</span><span style="color: #007700">-></span><span style="color: #0000BB">executeQuery</span><span style="color: #007700">(</span><span style="color: #DD0000">"test.asteroids"</span><span style="color: #007700">, </span><span style="color: #0000BB">$query</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">/* $cursor now contains an object that wraps around the result set. Use<br /> * foreach() to iterate over all the result */<br /></span><span style="color: #007700">foreach(</span><span style="color: #0000BB">$cursor </span><span style="color: #007700">as </span><span style="color: #0000BB">$document</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$document</span><span style="color: #007700">);<br />}<br /><br /></span><span style="color: #0000BB">?></span> </span> </code></div> </div> <div class="example-contents"><p>The above example will output something similar to:</p></div> <div class="example-contents screen"> <div class="cdata"><pre> stdClass Object ( [_id] => MongoDB\BSON\ObjectId Object ( [oid] => 5a4cff2f122d3321565d8cc2 ) [name] => Ceres [size] => 946 [distance] => 2.766 ) stdClass Object ( [_id] => MongoDB\BSON\ObjectId Object ( [oid] => 5a4cff2f122d3321565d8cc3 ) [name] => Vesta [size] => 525 [distance] => 2.362 } </pre></div> </div> </div> <div class="example" id="example-1723"> <p><strong>Example #2 Reading a result set for a tailable cursor</strong></p> <div class="example-contents"><p> <a href="https://docs.mongodb.com/manual/core/tailable-cursors" class="link external">» Tailable cursors</a> are a special type of MongoDB cursor that allows the client to read some results and then wait until more documents become available. These cursors are primarily used with <a href="https://docs.mongodb.com/manual/core/capped-collections" class="link external">» Capped Collections</a> and <a href="https://docs.mongodb.com/manual/changeStreams" class="link external">» Change Streams</a>. </p></div> <div class="example-contents"><p> While normal cursors can be iterated once with <em>foreach</em>, that approach will not work with tailable cursors. When <em>foreach</em> is used with a tailable cursor, the loop will stop upon reaching the end of the initial result set. Attempting to continue iteration on the cursor with a second <em>foreach</em> would throw an exception, since PHP attempts to rewind the cursor. Similar to result objects in other database drivers, cursors in MongoDB only support forward iteration, which means they cannot be rewound. </p></div> <div class="example-contents"><p> In order to continuously read from a tailable cursor, the Cursor object must be wrapped with an <a href="class.iteratoriterator.html" class="classname">IteratorIterator</a>. This allows the application to directly control the cursor's iteration, avoid inadvertently rewinding the cursor, and decide when to wait for new results or stop iteration entirely. </p></div> <div class="example-contents"><p> In order to demonstrate a tailable cursor in action, two scripts will be used: a "producer" and a "consumer". The producer script will create a new capped collection using the <a href="https://docs.mongodb.com/manual/reference/command/create" class="link external">» create</a> command and proceed to insert a new document into that collection each second. </p></div> <div class="example-contents"> <div class="phpcode"><code><span style="color: #000000"> <span style="color: #0000BB"><?php<br /><br />$manager </span><span style="color: #007700">= new </span><span style="color: #0000BB">MongoDB</span><span style="color: #007700">\</span><span style="color: #0000BB">Driver</span><span style="color: #007700">\</span><span style="color: #0000BB">Manager</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">$manager</span><span style="color: #007700">-></span><span style="color: #0000BB">executeCommand</span><span style="color: #007700">(</span><span style="color: #DD0000">'test'</span><span style="color: #007700">, new </span><span style="color: #0000BB">MongoDB</span><span style="color: #007700">\</span><span style="color: #0000BB">Driver</span><span style="color: #007700">\</span><span style="color: #0000BB">Command</span><span style="color: #007700">([<br /> </span><span style="color: #DD0000">'create' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'asteroids'</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">'capped' </span><span style="color: #007700">=> </span><span style="color: #0000BB">true</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">'size' </span><span style="color: #007700">=> </span><span style="color: #0000BB">1048576</span><span style="color: #007700">,<br />]));<br /><br />while (</span><span style="color: #0000BB">true</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">$bulkWrite </span><span style="color: #007700">= new </span><span style="color: #0000BB">MongoDB</span><span style="color: #007700">\</span><span style="color: #0000BB">Driver</span><span style="color: #007700">\</span><span style="color: #0000BB">BulkWrite</span><span style="color: #007700">;<br /> </span><span style="color: #0000BB">$bulkWrite</span><span style="color: #007700">-></span><span style="color: #0000BB">insert</span><span style="color: #007700">([</span><span style="color: #DD0000">'createdAt' </span><span style="color: #007700">=> new </span><span style="color: #0000BB">MongoDB</span><span style="color: #007700">\</span><span style="color: #0000BB">BSON</span><span style="color: #007700">\</span><span style="color: #0000BB">UTCDateTime</span><span style="color: #007700">]);<br /> </span><span style="color: #0000BB">$manager</span><span style="color: #007700">-></span><span style="color: #0000BB">executeBulkWrite</span><span style="color: #007700">(</span><span style="color: #DD0000">'test.asteroids'</span><span style="color: #007700">, </span><span style="color: #0000BB">$bulkWrite</span><span style="color: #007700">);<br /><br /> </span><span style="color: #0000BB">sleep</span><span style="color: #007700">(</span><span style="color: #0000BB">1</span><span style="color: #007700">);<br />}<br /><br /></span><span style="color: #0000BB">?></span> </span> </code></div> </div> <div class="example-contents"><p> With the producer script still running, a second consumer script may be executed to read the inserted documents using a tailable cursor, indicated by the <em>tailable</em> and <em>awaitData</em> options to <span class="function"><a href="mongodb-driver-query.construct.html" class="function">MongoDB\Driver\Query::__construct()</a></span>. </p></div> <div class="example-contents"> <div class="phpcode"><code><span style="color: #000000"> <span style="color: #0000BB"><?php<br /><br />$manager </span><span style="color: #007700">= new </span><span style="color: #0000BB">MongoDB</span><span style="color: #007700">\</span><span style="color: #0000BB">Driver</span><span style="color: #007700">\</span><span style="color: #0000BB">Manager</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">$query </span><span style="color: #007700">= new </span><span style="color: #0000BB">MongoDB</span><span style="color: #007700">\</span><span style="color: #0000BB">Driver</span><span style="color: #007700">\</span><span style="color: #0000BB">Query</span><span style="color: #007700">([], [<br /> </span><span style="color: #DD0000">'tailable' </span><span style="color: #007700">=> </span><span style="color: #0000BB">true</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">'awaitData' </span><span style="color: #007700">=> </span><span style="color: #0000BB">true</span><span style="color: #007700">,<br />]);<br /><br /></span><span style="color: #0000BB">$cursor </span><span style="color: #007700">= </span><span style="color: #0000BB">$manager</span><span style="color: #007700">-></span><span style="color: #0000BB">executeQuery</span><span style="color: #007700">(</span><span style="color: #DD0000">'test.asteroids'</span><span style="color: #007700">, </span><span style="color: #0000BB">$query</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">$iterator </span><span style="color: #007700">= new </span><span style="color: #0000BB">IteratorIterator</span><span style="color: #007700">(</span><span style="color: #0000BB">$cursor</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">$iterator</span><span style="color: #007700">-></span><span style="color: #0000BB">rewind</span><span style="color: #007700">();<br /><br />while (</span><span style="color: #0000BB">true</span><span style="color: #007700">) {<br /> if (</span><span style="color: #0000BB">$iterator</span><span style="color: #007700">-></span><span style="color: #0000BB">valid</span><span style="color: #007700">()) {<br /> </span><span style="color: #0000BB">$document </span><span style="color: #007700">= </span><span style="color: #0000BB">$iterator</span><span style="color: #007700">-></span><span style="color: #0000BB">current</span><span style="color: #007700">();<br /> </span><span style="color: #0000BB">printf</span><span style="color: #007700">(</span><span style="color: #DD0000">"Consumed document created at: %s\n"</span><span style="color: #007700">, </span><span style="color: #0000BB">$document</span><span style="color: #007700">-></span><span style="color: #0000BB">createdAt</span><span style="color: #007700">);<br /> }<br /><br /> </span><span style="color: #0000BB">$iterator</span><span style="color: #007700">-></span><span style="color: #0000BB">next</span><span style="color: #007700">();<br />}<br /><br /></span><span style="color: #0000BB">?></span> </span> </code></div> </div> <div class="example-contents"><p> The consumer script will start by quickly printing all available documents in the capped collection (as if <em>foreach</em> had been used); however, it will not terminate upon reaching the end of the initial result set. Since the cursor is tailable, calling <span class="function"><a href="iteratoriterator.next.html" class="function">IteratorIterator::next()</a></span> will block and wait for additional results. <span class="function"><a href="iteratoriterator.valid.html" class="function">IteratorIterator::valid()</a></span> is also used to check if there is actually data available to read at each step. </p></div> <blockquote class="note"><p><strong class="note">Note</strong>: <span class="simpara"> This example uses the <em>awaitData</em> query option to instruct the server to block for a short period (e.g. one second) at the end of the result set before returning a response to the driver. This is used to prevent the driver from aggressively polling the server when there are no results available. The <em>maxAwaitTimeMS</em> option may be used in conjunction with <em>tailable</em> and <em>awaitData</em> to specify the amount of time that the server should block when it reaches the end of the result set. </span> </p></blockquote> </div> </div> <div class="section"> <h2 class="title">Errors/Exceptions</h2> <p class="simpara"> When iterating over the cursor object, BSON data is converted into PHP variables. This iteration can cause the following Exceptions: </p> <ul class="simplelist"> <li class="member"> Throws <a href="class.mongodb-driver-exception-invalidargumentexception.html" class="classname">MongoDB\Driver\Exception\InvalidArgumentException</a> if a class in the type map cannot be instantiated or does not implement <span class="interfacename"><a href="class.mongodb-bson-unserializable.html" class="interfacename">MongoDB\BSON\Unserializable</a></span>. </li> <li class="member">Throws <a href="class.mongodb-driver-exception-unexpectedvalueexception.html" class="classname">MongoDB\Driver\Exception\UnexpectedValueException</a> if the input did not contain exactly one BSON document. Possible reasons include, but are not limited to, invalid BSON, extra data (after reading one BSON document), or an unexpected <a href="https://github.com/mongodb/libbson" class="link external">» libbson</a> error.</li> </ul> </div> </div> <h2>Table of Contents</h2><ul class="chunklist chunklist_reference"><li><a href="mongodb-driver-cursor.construct.html">MongoDB\Driver\Cursor::__construct</a> — Create a new Cursor (not used)</li><li><a href="mongodb-driver-cursor.getid.html">MongoDB\Driver\Cursor::getId</a> — Returns the ID for this cursor</li><li><a href="mongodb-driver-cursor.getserver.html">MongoDB\Driver\Cursor::getServer</a> — Returns the server associated with this cursor</li><li><a href="mongodb-driver-cursor.isdead.html">MongoDB\Driver\Cursor::isDead</a> — Checks if the cursor may have additional results</li><li><a href="mongodb-driver-cursor.settypemap.html">MongoDB\Driver\Cursor::setTypeMap</a> — Sets a type map to use for BSON unserialization</li><li><a href="mongodb-driver-cursor.toarray.html">MongoDB\Driver\Cursor::toArray</a> — Returns an array containing all results for this cursor</li></ul> </div> <hr /><div class="manualnavbar" style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="mongodb-driver-readconcern.isdefault.html">MongoDB\Driver\ReadConcern::isDefault</a></div> <div class="next" style="text-align: right; float: right;"><a href="mongodb-driver-cursor.construct.html">MongoDB\Driver\Cursor::__construct</a></div> <div class="up"><a href="book.mongodb.html">MongoDB\Driver</a></div> <div class="home"><a href="index.html">PHP Manual</a></div> </div></body></html>