型号:constRoom=newSchema({topic:String,messages:[{text:String,readByUsers:[String]//ArrayofusersIds,whichreadthismessage}]});示例数据:{topic:'First',messages:[{text:'Firstmessage',readByUsers:['id1','id3','id2']},{text:'Secondmessage',readByUsers:['id1','id2']//id3notreadthis}]},{topic:'Second',messag