MongoDB - How to remove field from element in nested array?

Question

I have the following structure for my document:

{
    "Name": "Test",
    "FieldsCollection": [{
        "GroupName": "Group",
        "Fields": [{
            "FieldName": "ABC",
            "Fields": {
                "item1": "value1",
                "item2": "value2"
            }
        }]
    }]
}

and I need to change it to be as follows:

{
    "Name": "Test",
    "FieldsCollection": [{
        "GroupName": "Group",
        "Fields": [{
            "FieldName": "ABC",
            "item1": "value1",
            "item2": "value2"
        }]
    }]
}

Assuming that the values for "item1": "value1","item2": "value2" are constant for all the documents in my collection, I thought I could just remove "FieldsCollection.Fields.Fields" and add "item1": "value1","item2": "value2"

I tried the following query:

db.getCollection('Devices').update(
    {"FieldsCollection.Fields.FieldName":"ABC"},
    {$unset: {"FieldsCollection.Fields.Fields":1}},
    {multi:true}
)

But it didn't work.

What query can I use to perform this change?

docs.mongodb.com/v3.6/reference/operator/update/positional/… — Alex Blex
– Alex Blex, Commented Jul 11, 2018 at 12:20
@AlexBlex, Does it mean it is not possible? I provided the query I used, can you help adjust it? — Liran Friedman
– Liran Friedman, Commented Jul 11, 2018 at 12:25
@PrajvalM, If it was I wouldn't be asking this question... Do you know why? — Liran Friedman
– Liran Friedman, Commented Jul 11, 2018 at 12:29

s7vr · Accepted Answer · 2018-07-12 01:19:52Z

8

Use positional $[all] (first level) & positional [<identifier>] (second level) in 3.6

Something like

db.getCollection('Devices').update(
    {"FieldsCollection.Fields.FieldName":"ABC"},
    {$unset: {"FieldsCollection.$[].Fields.$[f].Fields":1}, 
     $set:{"FieldsCollection.$[].Fields.$[f].item1":"value1",
           "FieldsCollection.$[].Fields.$[f].item2":"value2"}
    },  
    {arrayFilters: [{ "f.FieldName":"ABC"} ],multi:true }
)

edited Jul 12, 2018 at 1:19

answered Jul 11, 2018 at 12:37

s7vr

76.2k12 gold badges118 silver badges135 bronze badges

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

9 Comments

Liran Friedman Over a year ago

This gives the following error:

Failed to execute script.  Error: Fourth argument must be empty when specifying upsert and multi with an object. : DBCollection.prototype._parseUpdate@src/mongo/shell/collection.js:522:1 DBCollection.prototype.update@src/mongo/shell/collection.js:552:18 @(shell):1:1

Liran Friedman Over a year ago

No array filter found for identifier 'f' in path 'FieldsCollection.$[].Fields.$[f].Fields'

s7vr Over a year ago

Are you including the arrayFilters attribute in your query ? This works for me in mongo shell 3.6.

Liran Friedman Over a year ago

Could it be because I'm using RoboMongo?

Alex Blex Over a year ago

@LiranFriedman Yes, it doesn't work in robomongo. It works in the mongo shell, but it doesn't give you expected result. It removes Fields with all nested properties. It doesn't preserve "item1": "value1" and "item2": "value2".

|

pr0p · Accepted Answer · 2018-07-11 12:32:31Z

1

As your Fields.Fields is a object it is quite difficult.

This would be the query for removing :

db.getCollection('Devices').update(
    {Name : "test", "FieldsCollection.Fields.FieldName":"ABC"},
    {$unset: {"FieldsCollection.Fields.$.Fields":1}},
    {multi:true}
)

answered Jul 11, 2018 at 12:32

pr0p

2,34816 silver badges34 bronze badges

Collectives™ on Stack Overflow

MongoDB - How to remove field from element in nested array?

2 Answers 2

9 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

9 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related