Remove items from array of documents in Spring+Mongo

Question

I have a collection of documents like this in a mongo db :

"_id" : ObjectId("592bc37c339e7a23788b4c7c"),
"trips" : [ 
    {
        "tripGcsId" : "5937f86e339e7a2a58ac3186",
        "tripCounter" : NumberLong(1283),
        "tripRef" : "hjkhjk"
    }, 
    {
        "tripGcsId" : "5937f914339e7a2a58ac318b",
        "tripCounter" : NumberLong(1284),
        "tripRef" : "fjh"
    }
]

and a method on the server side (Spring+Mongo):

public List<String> removeTripObject( List<String> tripIds )
{
    Query query = Query.query( Criteria.where( "trips" ).elemMatch( Criteria.where( "tripGcsId" ).in( tripIds ) ) );

    Update update = new Update().pullAll( "trips.tripGcsId", new Object[] { tripIds } );
    getMongoTemplate().updateMulti( query, update, "ORDER" );
    return updatedOrders;
}

The parameter tripIds is a list of tripGcsIds to be removed from trips array. The method above gives me the error: Write failed with error code 16837 and error message 'cannot use the part (trips of trips.tripGcsId) to traverse the element.

When I try with the $ operator, as described in other SO answers like this:

public List<String> removeTripObject( List<String> tripIds )
{
    Query query = Query.query( Criteria.where( "trips" ).elemMatch( Criteria.where( "tripGcsId" ).in( tripIds ) ) );

    Update update = new Update().pullAll( "trips.$.tripGcsId", new Object[] { tripIds } );
    getMongoTemplate().updateMulti( query, update, "ORDER" );
    return updatedOrders;
}

i got this error: Write failed with error code 16837 and error message 'Can only apply $pullAll to an array.

I'm not sure how should this pullAll command look like on the server side.

As the error message says, you can do pull on an array. You are trying to do pull on `trips.tripGcsId` which is not an array. `trips` is an array — pvpkiran, Jun 07 '17 at 13:18

score 3 · Accepted Answer · answered Jun 07 '17 at 13:39

You need to use $pull update operator which takes the query to match and delete all the matching rows in embedded array.

Something like

public List<String> removeTripObject( List<String> tripIds ) {
    Query query = Query.query( Criteria.where( "tripGcsId" ).in( tripIds ) );
    Update update = new Update().pull("trips", query );
    getMongoTemplate().updateMulti( new Query(), update, "ORDER" );
    return updatedOrders;
}

Reference

https://docs.mongodb.com/manual/reference/operator/update/pull/#remove-items-from-an-array-of-documents

Remove items from array of documents in Spring+Mongo

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