MongoDB - Update nested array with many nested objects

Question

I need to update the dateP in the following structure with "2022-01-02", but it seems not an easy task:

{
  "_id": ObjectId("5c05984246a0201286d4b57a"),
  "_a": [
    {
      "_p": {
        "s": {
          "a": {}
        }
      }
    },
    {
      "_onlineStore": {}
    },
    {
      "_p": {
        "s": {
          "a": {
            "t": [
              {
                c: 4
              },
              {
                "dateP": "20200-09-20",
                "l": "English",
                "size": "XXL"
              },
              {
                c: 1
              }
            ]
          },
          c: {
            t: 2
          }
        }
      }
    }
  ]
}

playground

I attempted with arrayFilters, but without success as not all elements exist in all documents and some documents are pretty empty. Please advice.

MongoDB 4.2 community

it seems I am missing something maybe due to version is 4.2 but not working :( — R2D2
– R2D2, Commented Oct 12, 2022 at 13:20
Sad to hear that. But anyway it's weird, I don't think it is due to version issue. The docs for version 4.2 shows example for updating nested array elements. Fingers crossed. — Yong Shun
– Yong Shun, Commented Oct 12, 2022 at 13:25
ah found why: mongoplayground.net/p/vVxiFUc7LV_ , please, advice it happen that not all nested elements are present in all documents and it is normal — R2D2
– R2D2, Commented Oct 12, 2022 at 13:33
Here you go. Demo. It's like spamming the { $exists: true } 😂 — Yong Shun
– Yong Shun, Commented Oct 12, 2022 at 13:47

Yong Shun · Accepted Answer · 2022-10-12 13:16:31Z

2

Believe that you need the filtered positional operator for _a array to check whether the document has the _p field or not.

db.collection.update({},
{
  $set: {
    "_a.$[a]._p.s.a.t.$[x].dateP": "2022-01-02"
  }
},
{
  arrayFilters: [
    {
      "a._p": {
        $exists: true
      }
    },
    {
      "x.dateP": "20200-09-20"
    }
  ]
})

Demo @ Mongo Playground

answered Oct 12, 2022 at 13:16

Yong Shun

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5 Comments

nimrod serok Over a year ago

This is a very nice solution!

R2D2 Over a year ago

indeed I like it too but not working when there is not exisiting elements in the path ... :( , @Yong Shun , please , help with the fix and I will accept your answer.

nimrod serok Over a year ago

How about this? - just a small change

Yong Shun Over a year ago

Nice @nimrodserok, this works better in one line, rather than in my comment.

R2D2 Over a year ago

one more similar question if somebody interested: stackoverflow.com/questions/74043251/…

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