Spring with Querydsl :java.lang.ClassCastException

Question

I am trying to iterate query result of Querydsl. For iterating query result I am using for each loop.But I am getting class cast exception.

I want nBuildId for finding building name which is in building table. So how I can iterate this List<Tuple> for getting column.

I tried like this

 public  List<Tuple> loadUnclamiedRoomGrid(Integer nBuildId, String sFloor) {

        QRoom room = QRoom.room;        
        QRoomDepartmentMapping roomDepartmentMapping = QRoomDepartmentMapping.roomDepartmentMapping;

        JPAQuery<Tuple> query = new JPAQuery<Tuple>(em);

        query
             .from(room) 
             .where(room.nRoomId.notIn
                         (JPAExpressions.select(roomDepartmentMapping.nRoomId)
                               .from(roomDepartmentMapping)
                         )
               );

        if (nBuildId != null && nBuildId !=0) {
            query.where(room.nBuildId.eq(nBuildId));
        }

        if(sFloor != null) {
            query.where(room.sFloor.eq(sFloor));
        }   

        List<Tuple> queryResult = query.fetch();

        for(Tuple row : queryResult) {

            System.out.println("Build Id " +row.get(room.nBuildId));
        }

    return queryResult; 

    }

Error

message: "com.spacestudy.model.Room cannot be cast to com.querydsl.core.Tuple",
Exception: "java.lang.ClassCastException"

What is your query which gets executed? Can you share the entire method containing this code — codeLover
– codeLover, Commented Aug 31, 2018 at 11:15
Does changing List<Tuple> queryResult = query.fetch(); to List<Room> queryResult = query.fetch(); fix the exception? — leopal
– leopal, Commented Aug 31, 2018 at 12:09
its not taking List<Room> getting error as Type mismatch: cannot convert from List<Tuple> to List<Room> — SpringUser
– SpringUser, Commented Aug 31, 2018 at 12:16

Robert Bain · Accepted Answer · 2018-08-31 12:45:04Z

 public  List<Room> loadUnclamiedRoomGrid(Integer nBuildId, String sFloor) {

        QRoom room = QRoom.room;        
        QRoomDepartmentMapping roomDepartmentMapping = QRoomDepartmentMapping.roomDepartmentMapping;

        JPAQuery<Room> query = new JPAQuery<Room>(em);

        query
             .from(room) 
             .where(room.nRoomId.notIn
                         (JPAExpressions.select(roomDepartmentMapping.nRoomId)
                               .from(roomDepartmentMapping)
                         )
               );

        if (nBuildId != null && nBuildId !=0) {
            query.where(room.nBuildId.eq(nBuildId));
        }

        if(sFloor != null) {
            query.where(room.sFloor.eq(sFloor));
        }   

        List<Room> queryResult = query.fetch();

        for(Room row : queryResult) {

            System.out.println("Build Id " + room.nBuildId);
        }

    return queryResult; 

    }

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