MongoDB从集合中拉取数组元素

Question

我有一个mongodb对象如下:

array (
  '_id' => new MongoId("4cc97fb0247ae8747ec5fefb"),
  'posts' => 
  array (
    0 => 
    array (
      'comment' => 'Eamorr',
      'fromUname' => 'Eamorr',
      'time' => 1288273840,
      'UTC' => '2010-10-28T14:50:40+01:00',
      'ip' => '127.0.0.1',
      'id' => '123lasdfiqwoei28asdf',
    ),
    1 => 
    array (
      'comment' => 'Hello',
      'fromUname' => 'Eamorr',
      'time' => 1288277023,
      'UTC' => '2010-10-28T15:43:43+01:00',
      'ip' => '127.0.0.1',
      'id' => 'qopqwier982389qwfa',
    ),
    2 => 
    array (
      'comment' => 'Hello',
      'fromUname' => 'Anonymous',
      'time' => 1288283506,
      'UTC' => '2010-10-28T17:31:46+01:00',
      'ip' => '127.0.0.1',
      'id' => 'ioqwoeias892398wrf',
    ),
    /////
    //Want to remove element 3:
    /////
    3 => 
    array (
      'comment' => 'asdfasadf',
      'fromUname' => 'Anonymous',
      'time' => 1288283864,
      'UTC' => '2010-10-28T17:37:44+01:00',
      'ip' => '127.0.0.1',
      'id' => 'wwwwwiasdfn234oiasf',
    ),
    4 => 
    array (
      'comment' => 'asdfasdfasdf',
      'fromUname' => 'Anonymous',
      'time' => 1288284076,
      'UTC' => '2010-10-28T17:41:16+01:00',
      'ip' => '127.0.0.1',
      'id' => '290qwefoiqweproiqwerpq',
    ),
    5 => 
    array (
      'comment' => 'ASDF',
      'fromUname' => 'Eamorr',
      'time' => 1288284331,
      'UTC' => '2010-10-28T17:45:31+01:00',
      'ip' => '127.0.0.1',
      'id' => 'eioqw8923892hasdf',
    ),
    6 => 
    array (
      'comment' => 'ASDF2',
      'fromUname' => 'Eamorr',
      'time' => 1288284370,
      'UTC' => '2010-10-28T17:46:10+01:00',
      'ip' => '127.0.0.1',
      'id' => '23oaiofsaij234',
    ),
  ),
  'uname' => 'Eamorr',
)

现在,我正在编写一些PHP代码来删除帖子[x].我正在尝试使用$ pull来删除数组元素.

我有一个'id''wwwwwiasdfn234oiasf'(数组元素3),我想删除整个数组元素,只留下'posts'数组中的6个元素.

我试过谷歌搜索和查找文档无济于事...我仍然无法得到mongodb语法的悬念.

我在PHP中做这一切,但任何语言都可以,我应该能够进行翻译.

提前谢谢了,

解决方案(在PHP中):

$uname=whatever
$id=whatever
$mongo=new Mongo();
$walls=$mongo->people->walls;
$walls->update(array('uname'=>$uname),array('$pull'=>array('posts'=>array('id'=>$id))));

Answer 1

以下是使用MongoDB shell的方法.您应该能够将其翻译成PHP.

拉操作由$pull修饰符,字段选择器和值表达式组成.

{ $pull: { fieldSelector: valueExpression } }

在您的情况下,字段选择器是posts,因为这是您要更新的数组.用简单的英语表示的值表达式是

在id帖子中等于"wwwwwiasdfn234oiasf"

这转化为{ id: "wwwwwiasdfn234oiasf" }.如果我们将所有这些组合在一起,您将获得以下$pull语句,该语句将从数组中删除所需的项:

{ $pull: { posts: { id: "wwwwwiasdfn234oiasf" } } }