由于您具有嵌套数组，因此需要首先应用$unwind
运算符，以便在使用$lookup
管道之前对嵌入的文档进行反规范化（除非您已经在聚合操作中对其进行了展平）：
db.personaddress.aggregate([ { "$unwind": "$address" }, { "$unwind": "$address.location" }, { "$lookup": { "from": "places", "localField": "address.location.place._id", "foreignField": "_id", "as": "address.location.place", } }])然后可以实现为（未试用）：
LookupOperation lookupOperation = LookupOperation.newLookup() .from("places") .localField("address.location.place._id") .foreignField("_id") .as("address.location.place");Aggregation agg = newAggregation( unwind("address"), unwind("address.location"), lookupOperation );AggregationResults<Outputdocument> aggResults = mongoTemplate.aggregate( agg, PersonAddressdocument.class, Outputdocument.class);如果您的Spring Data版本不支持此功能，则一种解决方法是实施
AggregationOperation
接口以接受
DBObject：
public class CustomGroupOperation implements AggregationOperation { private DBObject operation; public CustomGroupOperation (DBObject operation) { this.operation = operation; } @Override public DBObject toDBObject(AggregationOperationContext context) { return context.getMappedObject(operation); }}然后$lookup
在聚合管道中将操作实现为DBObject：
DBObject lookupOperation = (DBObject)new BasicDBObject( "$lookup", new BasicDBObject("from", "places") .append("localField", "address.location.place._id") .append("foreignField", "_id") .append("as", "address.location.place") );然后可以将其用作：
Aggregation agg = newAggregation( unwind("address"), unwind("address.location"), lookupOperation );AggregationResults<Outputdocument> aggResults = mongoTemplate.aggregate( agg, PersonAddressdocument.class, Outputdocument.class);
