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MongoDB::command

(PECL mongo >=0.9.2)

MongoDB::command — 执行一条 Mongo 指令

说明

public array MongoDB::command ( array $command [, array $options = array() ] )

几乎所有不属于CRUD操作的事情都可以通过一条“数据库指令”完成。需要知道数据库的版本？有一条指令可以实现。需要进行一次聚合？有一条指令可以实现。想要提高日志级别？有一条指令可以实现。我想你已经领会到了。

该方法等同于：

  <?php

 public function  command ( $data ) {
    return  $this -> selectCollection ( '$cmd' )-> findOne ( $data );
}

 ?>

参数

command

要发送的指令

options

该参数是一个具有以下形式的关联数组： array("optionname" => <boolean>, ...)，现在支持的选项有：

"timeout"

Integer, defaults to MongoCursor::$timeout. If "safe" is set, this sets how long (in milliseconds) for the client to wait for a database response. If the database does not respond within the timeout period, a MongoCursorTimeoutException will be thrown.

更新日志

版本	说明
1.2.0	添加 options 参数，和一个选项:"timeout"。

返回值

返回数据库响应。每个响应都不会超过一个文档的大小，也就是不会超过16MB。结果文档的结构与执行的指令有关,但大部分结果都有 ok 字段来表示成功还是失败。以及 results 字段包含一个结果文档数组。

范例

Example #1 MongoDB::command() "distinct"实例

查找一个键的所有不重复值

  <?php

$people  =  $db -> people ;

 $people -> insert (array( "name"  =>  "Joe" ,  "age"  =>  4 ));
 $people -> insert (array( "name"  =>  "Sally" ,  "age"  =>  22 ));
 $people -> insert (array( "name"  =>  "Dave" ,  "age"  =>  22 ));
 $people -> insert (array( "name"  =>  "Molly" ,  "age"  =>  87 ));

 $ages  =  $db -> command (array( "distinct"  =>  "people" ,  "key"  =>  "age" ));

foreach ( $ages [ 'values' ] as  $age ) {
    echo  " $age \n" ;
}

 ?>

以上例程的输出类似于：

4
22
87

Example #2 MongoDB::command() "distinct"实例

查找一个键的所有不重复值，并且这些值大于等于18

  <?php

$people  =  $db -> people ;

 $people -> insert (array( "name"  =>  "Joe" ,  "age"  =>  4 ));
 $people -> insert (array( "name"  =>  "Sally" ,  "age"  =>  22 ));
 $people -> insert (array( "name"  =>  "Dave" ,  "age"  =>  22 ));
 $people -> insert (array( "name"  =>  "Molly" ,  "age"  =>  87 ));

 $ages  =  $db -> command (
    array(
         "distinct"  =>  "people" ,
         "key"  =>  "age" , 
         "query"  => array( "age"  => array( '$gte'  =>  18 ))
    )
);  

foreach ( $ages [ 'values' ] as  $age ) {
    echo  " $age \n" ;
}

 ?>

以上例程的输出类似于：

22
87

Example #3 MongoDB::command() MapReduce实例

获取所有有type=sale这样的"event"的用户，以及他们分别有几个这样的"event"（注:此处的event是一个集合的名字）

  <?php

 // sample event document
 $events -> insert (array( "user_id"  =>  $id , 
     "type"  =>  $type , 
     "time"  => new  MongoDate (), 
     "desc"  =>  $description ));

 // construct map and reduce functions
 $map  = new  MongoCode ( "function() { emit(this.user_id,1); }" );
 $reduce  = new  MongoCode ( "function(k, vals) { " .
     "var sum = 0;" .
     "for (var i in vals) {" .
         "sum += vals[i];" . 
     "}" .
     "return sum; }" );

 $sales  =  $db -> command (array(
     "mapreduce"  =>  "events" , 
     "map"  =>  $map ,
     "reduce"  =>  $reduce ,
     "query"  => array( "type"  =>  "sale" ),
     "out"  => array( "merge"  =>  "eventCounts" )));

 $users  =  $db -> selectCollection ( $sales [ 'result' ])-> find ();

foreach ( $users  as  $user ) {
    echo  " { $user [ '_id' ]}  had  { $user [ 'value' ]}  sale(s).\n" ;
}

 ?>

以上例程的输出类似于：

User 47cc67093475061e3d9536d2 had 3 sale(s).
User 49902cde5162504500b45c2c had 14 sale(s).
User 4af467e4fd543cce7b0ea8e2 had 1 sale(s).

Note: 使用 MongoCode

这个例子使用了 MongoCode，它还可以接受一个作用域参数。然而，现在 MongoDB 还不支持在 MapReduce 中使用它，如果你需要在MapReduce函数里用一个客户端参数，那么你可以在使用MapReduce的时候用“optional scope”字段把它们添加到全局作用域中，参考 » MapReduce文档来获得更多信息。

Note: out 参数

1.8.0以前，out 参数是可选的，如果你不使用它，MapReduce的结果将被写入一个临时集合里，这个临时集合会在连接关闭后删除。 1.8.0以后，out 参数是必须的，参考 » MapReduce documentation 来获得更多信息。

Example #4 MongoDB::command() "textSearch"实例

在MongoDB 2.4以上版本中使用全文检索功能（之前的版本不支持全文检索）。

  <?php
$m  = new  MongoClient ();
 $d  =  $m -> demo ;
 $c  =  $d -> planets ;

 $c -> insert (array( "name"  =>  "Mercury" ,  "desc"  =>  "Mercury is the smallest and closest to the Sun" ));
 $c -> insert (array( "name"  =>  "Venus" ,  "desc"  =>  "Venus is the second planet from the Sun, orbiting it every 224.7 Earth days." ));
 $c -> insert (array( "name"  =>  "Earth" ,  "desc"  =>  "Earth is the the densest of the eight planets in the Solar System." ));
 $c -> insert (array( "name"  =>  "Mars" ,  "desc"  =>  "Mars is named after the Roman god of war." ));

 $c -> ensureIndex (array( 'desc'  =>  'text' ));

 $r  =  $d -> command (array( "text"  =>  "planets" ,  'search'  =>  "sun"  ));
 print_r ( $r );
 ?>

以上例程的输出类似于：

Array
(
[queryDebugString] => sun||||||
[language] => english
[results] => Array
(
[0] => Array
(
[score] => 0.625
[obj] => Array
(
[_id] => MongoId Object
(
[$id] => 517549d944670a4a5cb3059a
)

[name] => Mercury
[desc] => Mercury is the smallest and closest to the Sun
)

)

[1] => Array
(
[score] => 0.55
[obj] => Array
(
[_id] => MongoId Object
(
[$id] => 517549d944670a4a5cb3059b
)

[name] => Venus
[desc] => Venus is the second planet from the Sun, orbiting it every 224.7 Earth days.
)

)

)

[stats] => Array
(
[nscanned] => 2
[nscannedObjects] => 0
[n] => 2
[nfound] => 2
[timeMicros] => 95
)

[ok] => 1
)

Example #5 MongoDB::command() "geoNear"实例

这个实例说明了如何使用 geoNear 指令。

  <?php
$m  = new  MongoClient ();
 $d  =  $m -> demo ;
 $c  =  $d -> poiConcat ;

 $r  =  $d -> command (array(
     'geoNear'  =>  "poiConcat" ,       // 在 poiConcat 集合中
     'near'  => array(- 0.08 ,  51.48 ),  // 搜索 51.48°N, 0.08°E 附近
     'spherical'  =>  true ,            // 启用特殊搜索
     'num'  =>  5 ,                     // 最多返回5个文档
 ));
 print_r ( $r );
 ?>

参见

MongoCollection::aggregate() - Perform an aggregation using the aggregation framework
MongoCollection::findAndModify() - Update a document and return it
MongoCollection::group() - Performs an operation similar to SQL's GROUP BY command

MongoDB 核心文档的 » 数据库指令，以及这些特定指令的文档 » findAndModify、 » getLastError、 » repairDatabase （还有很多其他指令，这只是一些例子）

用户评论:

[#1] nanhe dot kumar at gmail dot com [2013-08-21 21:41:14]

$db=new new Mongo();

Copy old_db to new_db

$responseCopy = $db->admin->command(array(
    'copydb' => 1,
    'fromhost' => 'localhost',
    'fromdb' => 'old_db',
    'todb' =>'new_db'
    ));

Now drop old_db

if($responseCopy['ok']==1){
$responseDrop=$db->old_db->command(array('dropDatabase' => 1));
//OR
$responseDrop =$db->old_db->drop();
}

Show Output

print_r($responseCopy);
print_r($responseDrop);

Output will be something like this

Array ( [ok] => 1 )
Array ( [dropped] => old_db [ok] => 1 )

[#2] mcuadros at gmail dot com [2013-04-09 11:13:54]

Command of Mongo 2.4 Text Search feature.

<?php
$result = $db->command(
    array(
        'text' => 'bar', //this is the name of the collection where we are searching
        'search' => 'hotel', //the string to search
        'limit' => 5, //the number of results, by default is 1000
        'project' => Array( //the fields to retrieve from db
            'title' => 1
        )
    )
);

[#3] Anonymous [2011-06-08 04:18:10]

> Need to know the database version? There's a command for that.

We didn't find it - ended up using either;

<?php $m = new Mongo(); $adminDB = $m->admin; //require admin priviledge $mongodb_info = $adminDB->command(array('buildinfo'=>true)); $mongodb_version = $mongodb_info['version']; print_r($mongodb_info); ?>

or

<?php $v = `mongo --version`; print_r($v); ?>

[#4] roman dot drapeko at gmail dot com [2011-04-16 02:07:08]

I tried to write MapReduce. Unfortunately, out => array('replace' => 'collName') did not work for me. Instead, the below code works

<?php $mongo->command(array( 'mapreduce' => 'events', 'map' => $map, 'reduce' => $reduce, 'out' => 'mapReduceEventStats' )); ?>

[#5] Min He [2010-07-21 04:31:58]

rename a collection:

<?php $m = new Mongo(); $adminDB = $m->admin; //require admin priviledge //rename collection 'colA' in db 'yourdbA' to collection 'colB' in another db 'yourdbB' $res = $adminDB->command(array( "renameCollection" => "yourdbA.colA", "to" => "yourdbB.colB" )); var_dump($res); ?>