MongoDB/PHP removing a specific array item inside the document

Question

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

Here's the structure:

{
    "_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")
        }
    ]
}

The full delete link is:

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

I tried several solutions,

-First one:

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

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

-Second:

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

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

-Third solution:

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

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.

How To add _id To emboded document (comments) in php

Amirouche
– Amirouche

2018-04-18 09:15:01 +00:00
Commented Apr 18, 2018 at 9:15 — Amirouche
– Amirouche, Commented Apr 18, 2018 at 9:15

Neil Lunn · Accepted Answer · 2018-06-10 00:42:51Z

4

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'] )
            )
        )
    )
);

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.

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

edited Jun 10, 2018 at 0:42

answered Sep 3, 2014 at 11:04

Neil Lunn

151k36 gold badges356 silver badges327 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Maciej Sitko Over a year ago

Thank you, I tried the solution you listed above several times, but forgot to put a new MongoId() indicator, instead, I was just putting there $_GET['id'] in a raw fashion, so it did not pull anything out of the array. Cheers!

Collectives™ on Stack Overflow

MongoDB/PHP removing a specific array item inside the document

1 Answer 1

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related