How to remove an element in double nested array in MongoDB

Question

I'm working on mongo, in this time in need to remove a specific element from array nested in another one, the structure is like the following:

{ 
    "_id" : ObjectId("5e616314946b6d3ac4ed8252"), 
    "uid" : "5db069478556622b4a0adca5", 
    "areas" : [
        {
            "name" : "mexico", 
            "elements" : [
                "23452345", 
                "24454675"
            ], 
        }, 
        {
            "name" : "usa", 
            "elemets" : [
                "123123123", 
                "1234334"
            ], 
        }
    ]
}

So I need a query that lets me remove any element in "elements" property.

I tried with this query but I couldn't reach it.

db.areas.update(
    { },
    { $pull: 
        { areas: { 
            $elemMatch: { 
                elements: { $eq : "123123123" }
                }
            }
        }
    },
    { multi:false }
);

This just said

WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 0 })

elements: { $eq : "123123123" } you can shortcut to elements: "123123123" — Wernfried Domscheit
– Wernfried Domscheit, Commented Mar 11, 2020 at 20:39
The input documents you have posted has some inconsistency; the sub-array field elements is different for the name: "usa"; it says elemets. — prasad_
– prasad_, Commented Mar 12, 2020 at 6:31

prasad_ · Accepted Answer · 2020-03-12 06:28:34Z

1

Here is the update for removing the specific array element in a sub-array (elements).

Note that to remove (pull) the specified element (elements value "24454675"), you need to specify the outer-array's element matching condition (note that there are two elements in the outer-array field areas).

db.areas.update(
   { "areas.name": "mexico" },
   { $pull: { "areas.$.elements":  "24454675" } }
)

NOTE: If you don't specify the { "areas.name": "mexico" } condition, the whole sub-document of the areas array will be removed.

answered Mar 12, 2020 at 6:28

prasad_

14.4k2 gold badges27 silver badges44 bronze badges

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

1 Comment

glinda93 Over a year ago

I've been trying to pull areas.elements but it keeps showing errmsg. It was areas.$.elements. Thanks for the answer!

Collectives™ on Stack Overflow

How to remove an element in double nested array in MongoDB

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related