The MongoCommandCursor class

(PECL mongo >=1.5.0)

简介

A command cursor is similar to a MongoCursor except that you use it for iterating through the results of a database command instead of a normal query. Command cursors are useful for iterating over large result sets that might exceed the document size limit (currently 16MB) of a single MongoDB::command() response.

While you can create command cursors using MongoCommandCursor::__construct() or the MongoCommandCursor::createFromDocument() factory method, you will generally want to use command-specific helpers such as MongoCollection::aggregateCursor().

Note that the cursor does not "contain" the database command's results; it just manages iteration through them. Thus, if you print a cursor (f.e. with var_dump() or print_r()), you will see the cursor object but not the result documents.

Cursor Stages

A MongoCommandCursor has two "life stages": pre- and post- command. When a cursor is created, it has not yet contacted the database, so it is in its pre-command state. When the client first attempts to get a result (by calling MongoCommandCursor::rewind(), directly or indirectly), the cursor moves into the post-command state.

The command cursor's batch size and socket timeout may be configured in both the pre- and post- command states.

Example #1 Adding options to MongoCommandCursor


<?php

$cursor = new MongoCommandCursor(...);

$cursor = $cursor->batchSize( 4 );

foreach ($cursor as $result) {
    var_dump($result);
}
?>

类摘要

MongoCommandCursor implements MongoCursorInterface , Iterator {

/* 方法 */

public batchSize ( int $batchSize ) : MongoCommandCursor

public __construct ( MongoClient $connection , string $ns , array $command = array() )

public static createFromDocument ( MongoClient $connection , string $hash , array $document ) : MongoCommandCursor

public current ( void ) : array

public dead ( void ) : bool

public getReadPreference ( void ) : array

public info ( void ) : array

public key ( void ) : int

public next ( void ) : void

public rewind ( void ) : array

public setReadPreference ( string $read_preference [, array $tags ] ) : MongoCommandCursor

public timeout ( int $ms ) : MongoCommandCursor

public valid ( void ) : bool

}

参见

MongoCommandCursor::batchSize — Limits the number of elements returned in one batch
MongoCommandCursor::__construct — Create a new command cursor
MongoCommandCursor::createFromDocument — Create a new command cursor from an existing command response document
MongoCommandCursor::current — Returns the current element
MongoCommandCursor::dead — Checks if there are results that have not yet been sent from the database
MongoCommandCursor::getReadPreference — Get the read preference for this command
MongoCommandCursor::info — Gets information about the cursor's creation and iteration
MongoCommandCursor::key — Returns the current result's index within the result set
MongoCommandCursor::next — Advances the cursor to the next result
MongoCommandCursor::rewind — Executes the command and resets the cursor to the start of the result set
MongoCommandCursor::setReadPreference — Set the read preference for this command
MongoCommandCursor::timeout — Sets a client-side timeout for this command
MongoCommandCursor::valid — Checks if the cursor is reading a valid result

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官方地址：https://www.php.net/manual/en/class.mongocommandcursor.php

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PHP官方手册 - 互联网笔记

The MongoCommandCursor class

简介

Cursor Stages

类摘要

参见

Table of Contents

User Contributed Notes