LINQ 联查多表数据并封装到ViewModel的实现

public List<MyTask> GetPagedTaskList(int pageIndex, int pageSize, string stuNum, int taskTypeId)

        {

            DbSet<T_TaskParticipation> taskParticipations = db.Set<T_TaskParticipation>();

            DbSet<T_TaskInformation> taskInformations = db.Set<T_TaskInformation>();

            DbSet<T_TaskType> taskTypes = db.Set<T_TaskType>();

            DbSet<T_MemberInformation> memberInformations = db.Set<T_MemberInformation>();

            List<MyTask> myTaskList = (from taskParticipation in taskParticipations

                        join taskInformation in taskInformations on taskParticipation.TaskId equals taskInformation.TaskId

                        join taskType in taskTypes on taskInformation.TaskTypeId equals taskType.TaskTypeId

                        join memberInformation in memberInformations on taskInformation.TaskSender equals memberInformation.StuNum

                        where taskParticipation.TaskReceiver == stuNum

                        && taskInformation.TaskTypeId == taskTypeId

                        select new MyTask()

                        {

                            TaskId=taskParticipation.TaskId,

                            TaskSender=taskInformation.TaskSender,

                            TaskName=taskInformation.TaskName,

                            TaskTypeId=taskInformation.TaskTypeId,

                            TaskContent=taskInformation.TaskContent,

                            TaskBegTime=taskInformation.TaskBegTime,

                            TaskEndTime=taskInformation.TaskEndTime,

                            TaskReceiver=taskParticipation.TaskReceiver,

                            TaskGrade=taskParticipation.TaskGrade,

                            IsRead=taskParticipation.IsRead,

                            IsComplete=taskParticipation.IsComplete,

                            TaskSenderName=memberInformation.StuName,

                            TaskTypeName=taskType.TaskTypeName

                        }).OrderBy(taskParticipation => taskParticipation.IsRead).ThenBy(taskParticipation => taskParticipation.TaskId).Skip((pageIndex - 1) * pageSize).Take(pageSize).ToList();

            return myTaskList;

}