PHP - Manual: MongoCollection::group

2024-12-23

MongoCollection::group

(PECL mongo >=0.9.2)

MongoCollection::group — Performs an operation similar to SQL's GROUP BY command

说明

public MongoCollection::group ( mixed $keys , array $initial , MongoCode $reduce [, array $options = array() ] ) : array

参数

keys

Fields to group by. If an array or non-code object is passed, it will be the key used to group results.

1.0.4+: If keys is an instance of MongoCode, keys will be treated as a function that returns the key to group by (see the "Passing a keys function" example below).

initial

Initial value of the aggregation counter object.

reduce

A function that takes two arguments (the current document and the aggregation to this point) and does the aggregation.

options

Optional parameters to the group command. Valid options include:

"condition"

Criteria for including a document in the aggregation.
"finalize"

Function called once per unique key that takes the final output of the reduce function.
"maxTimeMS"
Specifies a cumulative time limit in milliseconds for processing the operation on the server (does not include idle time). If the operation is not completed by the server within the timeout period, a MongoExecutionTimeoutException will be thrown.

返回值

Returns an array containing the result.

更新日志

版本	说明
1.5.0	Added "maxTimeMS" option.
1.2.11	Emits `E_DEPRECATED` when `options` is scalar.

范例

Example #1 MongoCollection::group() example

This groups documents by category and creates a list of names within that category.


<?php

$collection->insert(array("category" => "fruit", "name" => "apple"));
$collection->insert(array("category" => "fruit", "name" => "peach"));
$collection->insert(array("category" => "fruit", "name" => "banana"));
$collection->insert(array("category" => "veggie", "name" => "corn"));
$collection->insert(array("category" => "veggie", "name" => "broccoli"));

$keys = array("category" => 1);

$initial = array("items" => array());

$reduce = "function (obj, prev) { prev.items.push(obj.name); }";

$g = $collection->group($keys, $initial, $reduce);

echo json_encode($g['retval']);

?>

以上例程的输出类似于：

[{"category":"fruit","items":["apple","peach","banana"]},{"category":"veggie","items":["corn","broccoli"]}]

Example #2 MongoCollection::group() example

This example doesn't use any key, so every document will be its own group. It also uses a condition: only documents that match this condition will be processed by the grouping function.


<?php

$collection->save(array("a" => 2));
$collection->save(array("b" => 5));
$collection->save(array("a" => 1));

// use all fields
$keys = array();

// set intial values
$initial = array("count" => 0);

// JavaScript function to perform
$reduce = "function (obj, prev) { prev.count++; }";

// only use documents where the "a" field is greater than 1
$condition = array('condition' => array("a" => array( '$gt' => 1)));

$g = $collection->group($keys, $initial, $reduce, $condition);

var_dump($g);

?>

以上例程的输出类似于：

array(4) {
  ["retval"]=>
  array(1) {
    [0]=>
    array(1) {
      ["count"]=>
      float(1)
    }
  }
  ["count"]=>
  float(1)
  ["keys"]=>
  int(1)
  ["ok"]=>
  float(1)
}

Example #3 Passing a keys function

If you want to group by something other than a field name, you can pass a function as the first parameter of MongoCollection::group() and it will be run against each document. The return value of the function will be used as its grouping value.

This example demonstrates grouping by the num field modulo 4.


<?php

$c->group(new MongoCode('function(doc) { return {mod : doc.num % 4}; }'),
     array("count" => 0),
     new MongoCode('function(current, total) { total.count++; }'));

?>

add a note

User Contributed Notes 4 notes

down

nick at pitchinteractive dot com ¶

7 years ago


Here's my code to do an equivalent of a GROUP BY and a SUM



<?php

$contributionCol = $db->customers->contribution;

$group = $contributionCol->group(array('date' => true), array('sum' => 0), "function (obj, prev) { prev['sum'] += obj.amount; }");

?>



This groups by the 'date' column and sums over the 'amount' column. In my testing this was much slower than querying all rows and doing the Group by code with PHP. It could just be my particular setup and data set.



Also at first my amount column was a string, which caused the results to be concatenated rather than arithmetic addition, something else to watch out for.



[red.: Instead of this, please use the new aggregation framework. See the documentation for MongoCollection::aggregate]

down

ury dot zend at gmail dot com ¶

4 years ago


quoting Evgeniy Abduzhapparov example for correction, since is not working on newest php mongo driver version

instead of use:
<?php
$initial = array('tags'=>array(), 'count'=>0);
?>
for var tags, 
you have to cast the empty array to an object or use new stdClass()
<?php
$initial = array('tags'=> (object) array(), 'count'=>0);

$initial = array('tags'=> new stdClass(), 'count'=>0);
?>

down

-1

ronan dot guilloux at gmail dot com ¶

6 years ago


Since the $options argument is no longer a scalar (deprecated since the 1.2.11 version of the Mongo's PHP driver), you now must compose your $options as an associative array, otherwise you'll rise a "Implicitly passing condition as $options will be removed in the future" alert.

Example:

<?php

$m = new Mongo();
$db = $m->selectDB('test');
$collection = new MongoCollection($db, 'FooBar');

// grouping results by categories, where foo is 'bar' 
$keys = array('categorie'=>true, 'foo'=>true); // the fields list we want to return
$initial = array('count' => 0); // gets a subtotal for each categorie
$reduce = "function(obj,prev) { prev.count += 1; }"; // yes, this is js code
$conditions = array('foo'=> 'bar');
$grouped = $myColl::group($keys, $initial, $reduce, array('condition'=>$conditions));
$result = $grouped['retval'];

?>

down

-3

Evgeniy Abduzhapparov ¶

8 years ago


Here I am posting how I get tags from my documents. Documents should have 'tags' field which is array of strings:
{'tags':['php', 'mongo']}
<?php
$keys = array();
$initial = array('tags'=>array(), 'count'=>0);
$reduce = 'function (doc, total) { if (doc.tags.length) {doc.tags.forEach(function (e) {total.tags[e]=total.tags[e]||0; total.tags[e]++; total.count++;});} }';
$criteria = array(
    'condition' => array(
        'tags' => array('$exists'=>true)
    ),
);
?>

add a note

官方地址：https://www.php.net/manual/en/mongocollection.group.php

有任何技术问题请点击这里网站运营推广招聘

IT PHP 编程语言 Linux 开发编程科技 Elasticsearch HTML/CSS/XML 网络数据库 JAVA 面试 NoSQL C/C++ Golang Git 算法操作系统正则表达式 Redis 互联网 MySql JavaScript 运维软件国际架构设计 Mac OS TCP/IP Excel Vim Windows Socket Oracle VR MongoDB Python 运营 MemCache 商业硬件电子娱乐设计 nginx 摄影游戏 WordPress HTTP 团建数码电器

php7 安装fileinfo扩展 preg_split — 通过一个正则表达式分隔字符串 php位值,解决 PHP 中 usort 在值相同时改变原始位置的问题 [PHP] inet_pton/inet_ntop IP地址转换函数 [鸟哥]PHP_INT_MIN 和 -9223372036854775808 PHP 8.1 ADORecordSet对象 adodb手册 opcache预加载 Composer的Packagist资源 array_multisort() 多字段排序 PHPMailer设置utf8 PHPMailer字符集CharSet PHP json解析（json_decode）页面工具 php中几种注释规范 mysql面试题纯php实现DES以及TripleDES加密算法 [原创]诡异的php-fpm超时问题两千行PHP学习笔记 html转义/html编码/html解码 PHP5 扩展SOAP 调用 webservice

略微加速

PHP官方手册 - 互联网笔记

MongoCollection::group

说明

参数

返回值

更新日志

范例

User Contributed Notes 4 notes