The MongoCommandCursor class

(PECL mongo >=1.5.0)

Introduction

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);
}
?>

Class synopsis

MongoCommandCursor implements MongoCursorInterface , Iterator {
/* Methods */
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(): array
public dead(): bool
public getReadPreference(): array
public info(): array
public key(): int
public next(): void
public rewind(): array
public setReadPreference(string $read_preference, array $tags = ?): MongoCommandCursor
public timeout(int $ms): MongoCommandCursor
public valid(): bool
}

See Also

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