Support of MongoDB update $pull operation with expressions

[seblopez]

Hi all,
I was wondering if the Update pull method supports expressions of the type

{ $pull : { field : {field2: value} } } removes array elements with field2 matching value

{ $pull : { field : {$gt: 3} } } removes array elements greater than 3

{ $pull : { field : {<match-criteria>} } } removes array elements meeting match criteria

In particular my case is as follows:

public void removeByOfficeAndLastUpdatedDate(Long officeOid, Collection<Long> departureOids, Date olderThan) {

        Update cabinFareUpd = new Update();

        WriteResult updateResult = this.mongoTemplate.updateMulti(
            query(where(BaseFareFields.OFFICE_OID.getValue()).is(officeOid).
                and(BaseFareFields.DEPARTURE_OID.getValue()).in(departureOids).
                and(BaseFareFields.CABIN_FARE.getValue()).elemMatch(where(BaseFareFields.LAST_UPDATED_DATE.getValue()).lte(olderThan))),
            cabinFareUpd.pull(BaseFareFields.LAST_UPDATED_DATE.getValue(),
                query(where(BaseFareFields.LAST_UPDATED_DATE.getValue()).lte(olderThan))), BaseFare.class);

        logger.info(updateResult.toString());

    }

Basically I want to remove an array element within a document whose last udpated date is less that the informed date.

The execution of the pull method as written above currently throws an exception:

java.lang.StackOverflowError
	at java.util.HashMap$EntryIterator.<init>(Unknown Source)
	at java.util.HashMap$EntryIterator.<init>(Unknown Source)
	at java.util.HashMap.newEntryIterator(Unknown Source)
	at java.util.HashMap$EntrySet.iterator(Unknown Source)
	at java.util.AbstractMap.hashCode(Unknown Source)
	at org.springframework.util.ObjectUtils.nullSafeHashCode(ObjectUtils.java:336)
	at org.springframework.data.util.TypeDiscoverer.hashCode(TypeDiscoverer.java:365)
	at org.springframework.data.util.ClassTypeInformation.hashCode(ClassTypeInformation.java:39)
	at java.util.concurrent.ConcurrentHashMap.hash(Unknown Source)
	at java.util.concurrent.ConcurrentHashMap.get(Unknown Source)
	at org.springframework.data.mapping.context.AbstractMappingContext.getPersistentEntity(AbstractMappingContext.java:151)
...

I have attached the complete stack trace here Mongo Pull Stack Overflow exception 09-26-2012.zip
Thanks in advance for your help,

Sebastian

[seblopez]

I have refined the example a bit based on some additional research:
1) The elemMatch part has been removed per this note on MongoDB's explanation of the use of $pull with expressions: "Because of this feature, to use the embedded doc as a match criteria, you cannot do exact matches on array elements."
2) The key has been replaced to BaseFareFields.CABIN_FARE.getValue() as this is the array element in the document.
Thus here's the updated code:

public void removeByOfficeAndLastUpdatedDate(Long officeOid, Collection<Long> departureOids, Date olderThan) {

        Update cabinFareUpd = new Update();

        WriteResult updateResult = this.mongoTemplate.updateMulti(
            query(where(BaseFareFields.OFFICE_OID.getValue()).is(officeOid).and(BaseFareFields.DEPARTURE_OID.getValue())
                .in(departureOids)), 
            cabinFareUpd.pull(BaseFareFields.CABIN_FARE.getValue(),
                query(where(BaseFareFields.LAST_UPDATED_DATE.getValue()).lte(olderThan))), 
            BaseFare.class);

        logger.info(updateResult.toString());

    }

Either if I pass the object as query or criteria (just where(...)) I still get the same StackOverflow error...

What I am trying to reflect in the code is the following:

db.baseFare.update({ "officeOid" : 1 , "departureOid" : { "$in" : [ 70000]}}, { $pull : {cabinFare: { lastUpdatedDate: { $lte: new Date(2012, 8, 20) } } } }) => Using new Date just in javascript

Which I have tested and accomplishes what is expected i.e. removing a cabinFare whose lastUpdatedDate is less than or equal to 09/20/2012.

[seblopez]

I've come up with a solution that includes DBObject objects exposed directly as a way to deal with the nested expressions in the update:

    public void removeByOfficeAndLastUpdatedDate(Long officeOid, Collection<Long> departureOids, Date olderThan) {

        DBObject lastUpdatedDateUpd = new BasicDBObject(BaseFareFields.LAST_UPDATED_DATE.getValue(), new BasicDBObject(
            "$lte", olderThan));

        Update cabinFareUpd = new Update();

        cabinFareUpd.pull(BaseFareFields.CABIN_FARE.getValue(), lastUpdatedDateUpd);

        WriteResult updateResult = this.mongoTemplate.updateMulti(
            query(where(BaseFareFields.OFFICE_OID.getValue()).is(officeOid).and(BaseFareFields.DEPARTURE_OID.getValue())
                .in(departureOids)), cabinFareUpd,
            BaseFare.class);

        logger.info(updateResult.toString());

    }

Hope that it is useful to someone dealing with similar update requirements.

Cheers,

Sebastian