CODEWITHSUNDEEP
javascriptmongodb
user3142695
user3142695

Reputation: 17332

mongoDB: remove empty objects in an object-array

Unfortunately I got some false objects in an array in some documents, which are structured like this:

{
    "_id" : "8vJY4baMbdYkgHian",
    "title" : "Cars",
    "tradename" : [
        {

        },
        {
            "element" : "Audi"
        },
        {
            "element" : "Mercedes"
        }
    ]
}

As you can see in this example, the first object in the array is empty. How can I remove empty objects in all tradename-arrays of all documents in the collection?

Collection.update(
    { 'tradename': {} },
    { $pull: { 'tradename.$': '' } }
);

Upvotes: 4

Views: 6814

Answers (2)

Alex Blex
Alex Blex

Reputation: 37048

An alternative approach to remove empty objects from an array with no assumptions:

db.a.update(
    {"tradename": {}},
    { $pull: { 'tradename': {$in:[{}]} } },
    { "multi": true }
);

Upvotes: 6

chridam
chridam

Reputation: 103365

The following update operation using $pull updates all documents in the collection to remove empty objects from the array tradename, given that the embedded document has the element property only:

db.collection.update(
    { },
    { "$pull": { "tradename": { "element": { "$exists": false } } } },
    { "multi": true }
)

Upvotes: 1

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