MongoDB - Delete item in nested array

Question

I saw a lot of similar questions about this but couldn't make it work in my collection.

How can I delete a specific comment (you can assume that I know the userId).

For example, I want to remove comment with commentId=3 and I know that it's under userId=1.

[
{
    userId: "1",
    posts: [
        {
            postId: "2",
            comments: [
                {
                    commentId: "3",
                    ...
                },
                ...
            ]
        },
        ...
    ]
},
...
]

Thanks!

Dan Ionescu · Accepted Answer · 2020-05-13 09:36:35Z

1

This works with Mongodb 4.2 and will remove first array entry from "comments" if it matches the "commentId" 3

db.posts.update(
    {"userId" : "1"}, 
    {$pull : {"posts.$[].comments" : {"commentId":"3"}}}
)

If you would like to remove all array entries use:

db.posts.update(
    {"userId" : "1"}, 
    {$pull : {"posts.$[].comments" : {"commentId":"3"}}},
    {"multi": true}
)

answered May 13, 2020 at 9:36

Dan Ionescu

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1 Comment

user3343396 Over a year ago

Only one comment - update is deprecated, use updateOne/updateMany instead

user7583063 · Accepted Answer · 2020-05-13 09:22:33Z

0

Have you tried using the deleteOne()function ? try and have a look on MongoDb documentation. MongoDbDocumentation

answered May 13, 2020 at 9:22

user7583063

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