MongoDB - Update nested array with many nested objects

Question

I need to update the dateP in the following structure with "2022年01月02日", 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

• Yong Shun: Is this meet your requirement? Demo
• R2D2: it seems I am missing something maybe due to version is 4.2 but not working :(
• Yong Shun: 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.
• R2D2: 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
• Yong Shun: Here you go. Demo. It's like spamming the { $exists: true } 😂

Answer 1

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年01月02日"
 }
},
{
 arrayFilters: [
 {
 "a._p": {
 $exists: true
 }
 },
 {
 "x.dateP": "20200-09-20"
 }
 ]
})

Demo @ Mongo Playground

• nimrod serok: This is a very nice solution!
• R2D2: 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: How about this? - just a small change
• Yong Shun: Nice @nimrodserok, this works better in one line, rather than in my comment.
• R2D2: one more similar question if somebody interested: stackoverflow.com/questions/74043251/…