PHP MongoCursor Adds a top-level key/value pair to a query

说明

public MongoCursor::addOption ( string $key , mixed $value ) : MongoCursor

This is an advanced function and should not be used unless you know what you're doing.

A query can optionally be nested in a "query" field if other options, such as a sort or hint, are given. For instance, adding a sort causes the query to become a subfield of a bigger query object, like:

 <?php

$query = array("query" => $query, "orderby" => $sort);

?>

This method is for adding a top-level field to a query. It makes the query a subobject (if it isn't already) and adds the key/value pair of your chosing to the top level.

Warning

It cannot be used to add extra criteria to a query on the fly. For instance, this will not work:

 <?php

// NOT CORRECT
$cursor = $users->find()->addOption("name", "joe")->addOption("age", 20);

?>

This does not query for a user named "joe" with an age of 20.

参数

key: Fieldname to add.
value: Value to add.

返回值

Returns this cursor.

错误／异常

Throws MongoCursorException if this cursor has started iterating.

范例

Example #1 Adding a comment with MongoCursor::addOption() example

MongoDB supports special options to be send to the server. The shell uses the _addSpecial option to send a $comment to the server. This comment will show up in the profiling log (for slow queries f.e.). In the PHP driver, you use the MongoCursor::addOption() method.

 <?php
$m = new MongoClient;
$c = $m->demo->demo;
$cursor = $c->find();
$cursor->addOption('$comment', "This comment will show up in the profiling log");

foreach ($cursor as $document) { /* empty */ }
?>

以上例程的输出类似于：

{
    "op" : "query",
    "ns" : "demo.demo",
    "query" : {
        "$query" : {
             
        },
        "$comment" : "This comment will show up in the profiling log"
    },
    "cursorid" : 168463566447,
    "ntoreturn" : 0,
    "ntoskip" : 0,
    "nscanned" : 101,
    "nscannedObjects" : 101,
    "keyUpdates" : 0,
    "numYield" : 0,
…

Example #2 MongoCursor::addOption() example

Using MongoCursor::skip() to skip over millions of results can become slow. One way around this is to use $min or $max options for the query. These can be handy, but they require an index on exactly the fields being searched for. This is an example of how to use $min as an alternative to MongoCursor::skip().

 <?php

// make sure we have an index
$c->ensureIndex(array("ts" => 1));

// you may have to modify this to run in a reasonable amount of time on slow 
// machines (should take about 30 seconds on a good machine)
for ($i = 0; $i < 30000000; $i++) {
    $c->insert(array("ts" => new MongoDate(), "i" => $i));
}

$now = strtotime("now");

// find documents inserted in the last 2 seconds
$cursor = $c->find()->addOption('$min', array("ts" => $now-2));

?>