MongoDB - Update array data in array

Question

What is the best way to update the array element inside the array in MongoDB? For example, the data looks like this:

{
        "_id" : ObjectId("6201396b866ffbf1b84fb8f9"),
        "title" : "ironman",
        "comments" : [
                {
                        "text" : "nihao",
                        "replies" : [
                                {
                                        "text" : "hi"
                                },
                                {
                                        "text" : "bonjour"
                                },
                                {
                                        "text" : "push replies!!!"
                                }
                        ]
                },
                {
                        "text" : "what??",
                        "replies" : [
                                {
                                        "text" : "the"
                                },
                                {
                                        "text" : "hey"
                                }
                        ]
                },
                {
                        "text" : "push comments!!!"
                }
        ]
}

I want to change

"comments.replies.text: 'hi'"

to

"comments.replies.text: 'hello'"

What would be the best way to write a query if you want to update the elements inside replies?

There are many array update operators - you use then depending upon your use case. There are multiple replies within the comments array field. You need to tell which array element you want to update, etc. (more details). See Array Update Operators. — prasad_
– prasad_, Commented Feb 8, 2022 at 10:29
I can update comments by using db.movies.updateOne( { title: 'ironman', 'comments.text': 'hello' }, { $set: { 'comments.$.text': 'nihao' } } ) but, replies coudln't update the manner, ??? db.movies.updateOne( { title: 'ironman', 'comments.text': 'nihao' }, { { $set: { 'comments.$.replies.$.text': 'nihao' } } } ) — SeongBeom lee
– SeongBeom lee, Commented Feb 8, 2022 at 10:40
You want to update all replies - from hi to hello? You can use the arrayFilters option. — prasad_
– prasad_, Commented Feb 8, 2022 at 10:50
oh no, only replies - hi to hello. one element. "replies" : [ { "text" : "hi" }, { "text" : "bonjour" }, -> "replies" : [ { "text" : "hello" }, { "text" : "bonjour" }, — SeongBeom lee
– SeongBeom lee, Commented Feb 8, 2022 at 11:04

Yong Shun · Accepted Answer · 2022-02-08 11:07:50Z

1

You need $[<identifier>] filtered positional operator and arrayFilters to update nested document(s) in the array.

db.collection.update({
  title: "ironman"
},
{
  $set: {
    "comments.$[comment].replies.$[reply].text": "hello"
  }
},
{
  arrayFilters: [
    {
      "comment.replies": {
        $exists: true
      }
    },
    {
      "reply.text": "hi"
    }
  ]
})

Sample Demo on Mongo Playground

answered Feb 8, 2022 at 11:07

Yong Shun

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1 Comment

SeongBeom lee Over a year ago

thanks, solved this problem!!

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