Get the read preference for this command

# MongoCommandCursor::getReadPreference

(PECL mongo >=1.6.0)

MongoCommandCursor::getReadPreference — Get the read preference for this command

### 説明

public MongoCommandCursor::getReadPreference ( void ) : array

### パラメータ

この関数にはパラメータはありません。

### 返り値

この関数は、優先読み込みに関する配列を返します。配列に含まれる内容は、type (優先読み込みモードを表す文字列。MongoClient の定数に対応)、そして tagsets (すべてのタグセット条件のリスト) です。タグセットを指定しなかった場合は、tagsets は存在しません。

### 例

例1 MongoCommandCursor::getReadPreference() return value example

`<?php
$m = new MongoClient('mongodb://rs1.example.com:27017', array('replicaSet' => 'myReplSetName'));
$collection = $m->selectCollection('test', 'people');
// If a MongoCommandCursor is constructed directly, it will inherit the read
// preference of the MongoClient instance passed to its constructor; however,
// MongoCollection::aggregateCursor() will have the MongoCommandCursor inherit
// the collection's read preference.
$collection->setReadPreference(MongoClient::RP_SECONDARY);
$cursor = $collection->aggregateCursor( [
[ '$group' => [ '_id' => '$name', 'points' => [ '$sum' => '$points' ] ] ],
[ '$sort' => [ 'points' => -1 ] ],
] );
var_dump($cursor->getReadPreference());
?>`

上の例の出力は以下となります。

    array(1) {
      ["type"]=>
      string(9) "secondary"
    }

### 参考

- The read preferences documentation.
- MongoCommandCursor::setReadPreference() - Set the read preference for this command
- MongoCursorInterface::getReadPreference() - Get the read preference for this query