class BasePersistentObject {
 final Map _map = objectory.dataMapDecorator(new LinkedHashMap());
 Map get map => _map;
 set map(Map newValue) {
   _setMap(newValue);
 }
 Set<String> _dirtyFields;
 Map<String,dynamic> _compoundProperties;
 bool saveOnUpdate = false;
 BasePersistentObject() {
   _setMap(map);
 }
 void _setMap(Map newValue) {
   if (newValue == null || newValue.isEmpty) {
     _initMap();
   } else {
     _map.clear();
     newValue.forEach((k, v) => _map[k] = v);
   }
   _compoundProperties = new Map<String,dynamic>();
   init();
   _dirtyFields = new Set<String>();
 }
 Set<String> get dirtyFields => _dirtyFields;
 EmbeddedPersistentObject getEmbeddedObject(Type classType, String property) {
   EmbeddedPersistentObject result = _compoundProperties[property];
   if (result == null) {
     result = objectory.newInstance(classType);
     result._setMap(map[property]);
     map[property] = result.map;
     result._parent = this;
     result._pathToMe = property;
   }
   return result;
 }
 PersistentList getPersistentList(Type classType, String property) {
   PersistentList result = _compoundProperties[property];
   if (result == null) {
     result = new PersistentList(this,classType,property);
     _compoundProperties[property] = result;
   }
   return result;
 }
 
 PersistentObject getLinkedObject(String property) {
   DbRef dbRef = map[property];
   if (dbRef == null) {
     return null;
   }
   Type classType = objectory.getClassTypeByCollection(dbRef.collection);
   return objectory.findInCacheOrGetProxy(dbRef.id,classType);
 }

 setLinkedObject(String property, PersistentObject value) {
   if (value == null) {
     map[property] = null;
   } else {
     if (value.id == null) {
       throw new Exception('Attemt to set link to unsaved object: $value');
     }
     onValueChanging(property, value.dbRef);
     map[property] = value.dbRef;
   }
 }
 void _initMap() {
 }

 void setDirty(String fieldName) {
   if (_dirtyFields == null){
     return;
   }
   _dirtyFields.add(fieldName);
 }

 void clearDirtyStatus() {
   _dirtyFields.clear();
 }

 void onValueChanging(String fieldName, newValue) {
   setDirty(fieldName);
 }

 isDirty() {
   return !_dirtyFields.isEmpty;
 }


 void setProperty(String property, value){
   onValueChanging(property, value);
   this.map[property] = value;
 }

 dynamic getProperty(String property){
   return this.map[property];
 }

 String toString()=>"$collectionName($map)";

 void init(){}
 
 /// Name of MongoDB collection where instance of this class would  be persistet in DB.
 /// By default equals to class name, but may be overwritten
 String get collectionName => runtimeType.toString();

 Future<PersistentObject> fetchLinks(){
   var dbRefs = new List<DbRef>();
   getDbRefsFromMap(map, dbRefs);
   var objects = dbRefs.map((each) => objectory.dbRef2Object(each));
   return Future.forEach(objects,(each) => each.fetch()).then((_)=>new Future.value(this));
 }

 getDbRefsFromMap(Map map, List result){
   for(var each in map.values){
     if (each is DbRef) {
       result.add(each);
     }
     if (each is Map) {
       getDbRefsFromMap(each, result);
     }
     if (each is List) {
       getDbRefsFromList(each, result);
     }
   }
 }
 getDbRefsFromList(List list, List result){
   for (var each in list) {
     if (each is DbRef) {
       result.add(each);
     }
     if (each is Map) {
       getDbRefsFromMap(each, result);
     }
     if (each is List) {
       getDbRefsFromList(each, result);
     }
   }
 }

}