返工 linq 查询以返回嵌套对象

Question

Im having a db table like this

And my query linq looks like

   var selectedNotifications = _dbContext.UserNotificationTypeDeliveryChoice
    .Include(m => m.NotificationGroup)
    .Include(m => m.DeliveryType)
    .Where(m => m.UserDefId == userDefId && m.UserTypeId == (int)userType)
    .Select(m => new NotificationGroup()
    {
      NotificationGroupId = m.NotificationGroup.NotificationGroupId,
      Name = m.NotificationGroup.Name,
      DefaultDeliveryType = m.DeliveryType,
      HasChoosen = true
    }).ToList();

In my model I used virtual prop to fill in foreign key property DeliveryType. It looks like this (JSON):

[
  {
    "notificationGroupId": 1,
    "name": "Comments",
    "defaultDeliveryType": {
      "deliveryTypeId": 2,
      "name": "Email"
    },
    "hasChoosen": true
  },
  {
    "notificationGroupId": 2,
    "name": "Q&A",
    "defaultDeliveryType": {
      "deliveryTypeId": 2,
      "name": "Email"
    },
    "hasChoosen": true
  },
  {
    "notificationGroupId": 3,
    "name": "Services",
    "defaultDeliveryType": {
      "deliveryTypeId": 2,
      "name": "Email"
    },
    "hasChoosen": true
  },
  {
    "notificationGroupId": 4,
    "name": "Trial",
    "defaultDeliveryType": {
      "deliveryTypeId": 2,
      "name": "Email"
    },
    "hasChoosen": true
  },
  {
    "notificationGroupId": 4,
    "name": "Trial",
    "defaultDeliveryType": {
      "deliveryTypeId": 1,
      "name": "SMS"
    },
    "hasChoosen": true
  }
]

However, I have multiple records for same NotificationGroupId, and I would like to have list as follows:

[
  {
    "notificationGroupId": 4,
    "name": "Trial",
    "defaultDeliveryType": {
      "deliveryTypeId": 1,
      "name": "SMS"
    },
    "defaultDeliveryType": {
        "deliveryTypeId": 2,
        "name": "Email"
      },
    "hasChoosen": true
  }
]

Please notice the difference for "notificationGroupId": 4, it need to has nested delivery types.

Update #1 I managed to achieve something, but still I need to map to my model with Select projector statement.

Here is an example:

var selectedNotifications = _dbContext.UserNotificationTypeDeliveryChoice
                            .Include(m => m.NotificationGroup)
                            .Include(m => m.DeliveryType)
                            .Where(m => m.UserDefId == userDefId && m.UserTypeId == (int)userType)
                            .GroupBy(p => p.NotificationGroupId,
                                     p => p.DeliveryType,
                                     (key, g) => new { NotificationGroupId = key, DeliveryTypes = g });

Update #2 strong text

    public class UserNotificationTypeDeliveryChoice
    {
        public List<NotificationGroup> NotificationGroups { get; set; }
        //public List<DeliveryType> DeliveryTypes { get; set; }
        public long UserNotificationTypeDeliveryChoiceId { get; set; }
        public int? UserDefId { get; set; }
        public int? UserCompanyOrInstitutionId { get; set; }
        public byte NotificationGroupId { get; set; }
        public byte DeliveryTypeId { get; set; }
        public int UserTypeId { get; set; }
        public virtual DeliveryType DeliveryType { get; set; }
        public virtual NotificationGroup NotificationGroup { get; set; }
        public virtual UserDef UserDef { get; set; }
    }

and Model for NotificationGroup and DeliveryType:

    public class NotificationGroup
    {
        public NotificationGroup()
        {
            UserNotificationTypeDeliveryChoice = new HashSet<UserNotificationTypeDeliveryChoice>();
            NotificationGroupUserType = new HashSet<NotificationGroupUserType>();
        }
        //public List<DeliveryType> DeliveryTypes { get; set; }
        public byte NotificationGroupId { get; set; }
        public string Name { get; set; }
        public string Description { get; set; }
        //public bool HasChoosen { get; set; }
        public virtual DeliveryType DefaultDeliveryType { get; set; }
        public byte DefaultDeliveryTypeId { get; set; }
        public virtual ICollection<UserNotificationTypeDeliveryChoice> UserNotificationTypeDeliveryChoice { get; set; }
        public virtual ICollection<NotificationGroupUserType> NotificationGroupUserType { get; set; }
    }

    public class DeliveryType
    {
        public DeliveryType()
        {
            NotificationGroup = new HashSet<NotificationGroup>();
            UserNotificationTypeDeliveryChoice = new HashSet<UserNotificationTypeDeliveryChoice>();
            NotificationGroupUserType = new HashSet<NotificationGroupUserType>();
        }

        public byte DeliveryTypeId { get; set; }
        public string Name { get; set; }
        public string Description { get; set; }

        public virtual ICollection<NotificationGroup> NotificationGroup { get; set; }
        public virtual ICollection<UserNotificationTypeDeliveryChoice> UserNotificationTypeDeliveryChoice { get; set; }
        public virtual ICollection<NotificationGroupUserType> NotificationGroupUserType { get; set; }
    }
}

Here is my model description which is mapped through EF Core:

Answer 1

If you have a non-unique ID, you cannot group by NotificationGroup, you have to stick with ID.

To keep the Name of NotifigrationGroup, you have to keep the NotificationGroup as the TElement of the GroupBy. (That's why p=>p.)

Later in the Result selector, you can pick a name from one of the elements, just pick the name of the first NotificationGroup. And here you can Select the DeliveryTypes, if you like.

var selectedNotifications = _dbContext.UserNotificationTypeDeliveryChoice
                            .Include(m => m.NotificationGroup)
                            .Include(m => m.DeliveryType)
                            .Where(m => m.UserDefId == userDefId && m.UserTypeId == (int)userType)
                            .GroupBy( p => p.NotificationGroupId, p => p, 
                    (key,g) => new { 
                         NotificationId = key, 
                         Name = g.First().Name, 
                         DeliveryTypes = g.Select(x => x.DeliveryTypes)
                               }););