MongoDB Aggregation of Parent document field in Spring - 


i unable aggregate field parent document,  example:  class animal {    int legs;    int eyes;    hashmap<string, object> subspecies; }     class tiger extends animal{ int id; string name; string category; }  public static void main(string args[]) {      unwindoperation unwind = unwind("$subspecies");     aggregation agg = aggregation.newaggregation(            aggregation.match(criteria.where("category").is("tigers")),            unwind,           aggregation.group("subspecies.bengaltiger").count().as("count"),          project("count","subspecies.bengaltiger").and("subspecies.bengaltiger").previousoperation(),    aggregation.sort(sort.direction.desc, "count")   );   myservices services = new myservices();   //convert aggregation result list   list<tigergroupcount> result =           services.getaggregationlist(agg, tiger.class, tigergroupcount.class);   system.out.println("result:" + result + ",,,,,,,,,," + result.size());     (tigergroupcount tigergroupcount: result) {     system.out.println("status : " + tigergroupcount.groupname);     system.out.println("count : " + tigergroupcount.count);   }     mlogger.info(""+result.size()); }  class tigergroupcount {    int id;    string groupname;    long count; }

but here, able aggregate tiger.name field direct field in tiger.class. need access field - subspecies in parent class(animal.class). small appreciable. thank in advance.


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