Suche in Mongodb-Aggregation

Da Sie verschachtelte Arrays haben, müssen Sie $unwind anwenden Operator zuerst, um die eingebetteten Dokumente zu denormalisieren, bevor $lookup verwendet wird Pipeline (es sei denn, Sie haben sie bereits in Ihrem Aggregationsvorgang vereinfacht):

db.personaddress.aggregate([
    { "$unwind": "$address" },
    { "$unwind": "$address.location" },
    {
        "$lookup": {
            "from": "places", 
            "localField": "address.location.place._id", 
            "foreignField": "_id", 
            "as": "address.location.place", 
        }
    }
])

was dann implementiert werden kann als (ungetestet):

LookupOperation lookupOperation = LookupOperation.newLookup()
    .from("places")
    .localField("address.location.place._id")
    .foreignField("_id")
    .as("address.location.place");

Aggregation agg = newAggregation(
    unwind("address"),
    unwind("address.location"),
    lookupOperation  
);

AggregationResults<OutputDocument> aggResults = mongoTemplate.aggregate(
    agg, PersonAddressDocument.class, OutputDocument.class
);

Wenn Ihre Spring Data-Version dies nicht unterstützt, besteht eine Problemumgehung darin, die AggregationOperation zu implementieren Schnittstelle, um ein DBObject aufzunehmen :

public class CustomGroupOperation implements AggregationOperation {
    private DBObject operation;

    public CustomGroupOperation (DBObject operation) {
        this.operation = operation;
    }

    @Override
    public DBObject toDBObject(AggregationOperationContext context) {
        return context.getMappedObject(operation);
    }
}

Implementieren Sie dann $lookup Betrieb als DBObject in der Aggregationspipeline:

DBObject lookupOperation = (DBObject)new BasicDBObject(
    "$lookup", new BasicDBObject("from", "places")
        .append("localField", "address.location.place._id")
        .append("foreignField", "_id")
        .append("as", "address.location.place")       
);

die Sie dann verwenden können als:

Aggregation agg = newAggregation(
    unwind("address"),
    unwind("address.location"),
    lookupOperation  
);

AggregationResults<OutputDocument> aggResults = mongoTemplate.aggregate(
    agg, PersonAddressDocument.class, OutputDocument.class
);