MongoDB/PHP删除文档中的特定数组项 [英] MongoDB/PHP removing a specific array item inside the document

问题描述

现在，我的收藏夹中有一个文档，我希望在单击时删除该文档，这些文档就是帖子文档中的注释.

Now, I have a document in my collection that I would like to delete on click, and those are comments inside the post document.

结构如下:

{
    "_id" : "design-patterns-vs-frameworks",
    "title" : "Design Patterns vs Frameworks",
    "category" : [ 
        "Frameworks", 
        " Design Patterns", 
        " PHP"
    ],
    "date_time" : ISODate("2014-09-02T13:45:29.124Z"),
    "description" : "Frameworks vs Design Patterns",
    "content" : " Content!",
    "author" : "Maciej Sitko",
    "comments" : [ 
        {
            "_id" : ObjectId("54061528af105b51133c986c"),
            "comment" : "ashfklsfsl\r\n",
            "author" : "maciejsitko",
            "date" : ISODate("2014-09-02T19:06:16.646Z")
        }, 
        {
            "_id" : ObjectId("5406152caf105b51133c986d"),
            "comment" : "lfasdlfsfl",
            "author" : "maciejsitko",
            "date" : ISODate("2014-09-02T19:06:20.652Z")
        }
    ]
}

完整的删除链接为:

delete.php?post = css-clearfix-explained& id = 540617e3af105b8d133c986a (如您所见，有两个get变量'post'和'id')

delete.php?post=css-clearfix-explained&id=540617e3af105b8d133c986a (as you see two get variables 'post' and 'id')

我尝试了几种解决方案，

I tried several solutions,

-第一个:

$collection->update( array("_id" => $_GET['post']), array( '$unset' => 
 array("comments" => array("_id" => $_GET['id']))) );

这只是删除了我的所有评论数组中的评论.

This one just removed all of my comments inside the comments array.

-第二:

$delete = array('$pull' => array("comments" => array( '_id' => $_GET['id'])));
$collection->update(array('_id' => $_GET['post']), $delete);

没有做太多事情，奇怪的是，这应该起作用，对吧?

Did not pretty much do anything, strangely enough, this should work, right?

-第三种解决方案:

$collection->remove( array('_id' => $_GET['post'], 'comments._id' => $_GET['id']));

实现此目标的正确方法是什么?我为此付出了很多努力，甚至实现了一些聚合查询，但都没有解决.

What would be the proper way of achieving this? I struggled on this one a lot, even implementing some aggregation query and it didn't work out.

推荐答案

要从数组中删除元素，请使用

To remove an element from an array you use the $pull operator. This takes a "query" expression to identify the element you wish to remove:

$collection->update( 
    array("_id" => $_GET['post']),
    array( '$pull' => 
        array(
            "comments" => array(
                "_id" => new MongoId( $_GET['id'] )
            )
        )
    )
);

$pull的查询"部分作用于指定数组的各个元素，因此任何与条件匹配的内容都将从数组中删除.但同样重要的是，您的请求参数是字符串"，因此您需要将其强制转换为实际的ObjectId值，您可以使用

The "query" portion of $pull acts on the individual elements of the array specified, so anything matching the condition will be removed from the array. But also importantly your request parameter is a "string" so you need to cast this as an actual ObjectId value which you can cast in PHP with the MongoId class from the driver.

注意 现代驱动程序版本使用 MongoDB\BSON\ObjectId 作为转换字符串十六进制值"的正确方法转换成实际的ObjectId表示形式.

NOTE Modern driver releases use MongoDB\BSON\ObjectId as the correct method for casting "string hex value" into an actual ObjectId representation.

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