【发布时间】：2020-02-19 20:12:11
【问题描述】：
我正在为 .NET Core 中的 API 构建一个演示，并构建一个嵌套的 JSON 对象，该对象需要通过一系列 LINQ 查询来构建。
我当前的问题是，当我得到大约 4 层深度时，我想自定义实际序列化的内容，更具体地说，我想专门为此查询“不包括”特定导航属性，但不是出于一般目的，仅对于这个特定的查询。
我的第一个想法是做一个 DTO，但这似乎是一个不必要的额外模型，仅针对这个特定情况......我想直接使用 LINQ 来处理我的结果。
我已经在我的 Startup.cs 文件中添加了以下内容以避免循环：
services.AddControllers().AddNewtonsoftJson(options =>
options.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore
);
我目前有 5 个正在运行的模型，如下所示：
public class Hotel
{
public int ID { get; set; }
public string Name { get; set; }
public string StreetAddress { get; set; }
public string City { get; set; }
public string State { get; set; }
public string Phone { get; set; }
public List<HotelRooms> HotelRooms { get; set; }
}
public class Room
{
public int ID { get; set; }
public string Name { get; set; }
public Layout Layout { get; set; }
public List<RoomAmenities> RoomAmenities { get; set; }
public List<HotelRooms> HotelRooms { get; set; }
}
public class HotelRooms
{
public int HotelID { get; set; }
public int RoomNumber { get; set; }
public int RoomID { get; set; }
public decimal Rate { get; set; }
public bool PetFriendly { get; set; }
public Hotel Hotel { get; set; }
public Room Room { get; set; }
}
public class Amenities
{
public int ID { get; set; }
public string Name { get; set; }
// Navigation Properties
public List<RoomAmenities> RoomAmenities { get; set; }
}
public class RoomAmenities
{
public int RoomID { get; set; }
public int AmenitiesID { get; set; }
public Room Room { get; set; }
public Amenities Amenity { get; set; }
}
在我的服务中，我有这个实际上是在做查询的逻辑：
public async Task<Hotel> GetById(int id)
{
var hotel = await _context.Hotel.FindAsync(id);
// Get a list of rooms
var rooms = await _context.HotelRooms.Where(r => r.HotelID == id)
.Include(d => d.Room)
.ThenInclude(a => a.RoomAmenities)
.ThenInclude(x => x.Amenity).ToListAsync();
hotel.HotelRooms = rooms;
return hotel;
}
当前输出为：
{
"id": 1,
"name": "Amanda's Hotel",
"streetAddress": "123 CandyCane Lane",
"city": "Seattle",
"state": "WA",
"phone": "123-456-8798",
"hotelRooms": [
{
"hotelID": 1,
"roomNumber": 101,
"roomID": 2,
"rate": 75.00,
"petFriendly": false,
"room": {
"id": 2,
"name": "Queen Suite",
"layout": 2,
"roomAmenities": [
{
"roomID": 2,
"amenitiesID": 1,
"amenity": {
"id": 1,
"name": "Coffee Maker",
"roomAmenities": [
{
"roomID": 1,
"amenitiesID": 1,
"room": {
"id": 1,
"name": "Princess Suite",
"layout": 1,
"roomAmenities": [
{
"roomID": 1,
"amenitiesID": 2,
"amenity": {
"id": 2,
"name": "Mini Bar",
"roomAmenities": []
}
}
],
"hotelRooms": [
{
"hotelID": 1,
"roomNumber": 123,
"roomID": 1,
"rate": 120.00,
"petFriendly": true
}
]
}
}
]
}
}
],
"hotelRooms": []
}
},
{
"hotelID": 1,
"roomNumber": 123,
"roomID": 1,
"rate": 120.00,
"petFriendly": true,
"room": {
"id": 1,
"name": "Princess Suite",
"layout": 1,
"roomAmenities": [
{
"roomID": 1,
"amenitiesID": 1,
"amenity": {
"id": 1,
"name": "Coffee Maker",
"roomAmenities": [
{
"roomID": 2,
"amenitiesID": 1,
"room": {
"id": 2,
"name": "Queen Suite",
"layout": 2,
"roomAmenities": [],
"hotelRooms": [
{
"hotelID": 1,
"roomNumber": 101,
"roomID": 2,
"rate": 75.00,
"petFriendly": false
}
]
}
}
]
}
},
{
"roomID": 1,
"amenitiesID": 2,
"amenity": {
"id": 2,
"name": "Mini Bar",
"roomAmenities": []
}
}
],
"hotelRooms": []
}
}
]
}
这对我来说太嵌套了，我希望不包括“amenity”对象内的内部“roomAmenities”。我希望我的对象看起来像这样：
{
"id": 1,
"name": "Amanda's Hotel",
"streetAddress": "123 CandyCane Lane",
"city": "Seattle",
"state": "WA",
"phone": "123-456-8798",
"hotelRooms": [
{
"hotelID": 1,
"roomNumber": 101,
"roomID": 2,
"rate": 75,
"petFriendly": false,
"room": {
"id": 2,
"name": "Queen Suite",
"layout": 2,
"roomAmenities": [
{
"roomID": 2,
"amenitiesID": 1,
"amenity": {
"id": 1,
"name": "Coffee Maker"
}
}
],
"hotelRooms": []
}
},
{
"hotelID": 1,
"roomNumber": 123,
"roomID": 1,
"rate": 120,
"petFriendly": true,
"room": {
"id": 1,
"name": "Princess Suite",
"layout": 1,
"roomAmenities": [
{
"roomID": 1,
"amenitiesID": 1,
"amenity": {
"id": 1,
"name": "Coffee Maker"
}
},
{
"roomID": 1,
"amenitiesID": 2,
"amenity": {
"id": 2,
"name": "Mini Bar"
}
}
],
"hotelRooms": []
}
}
]
}
有人对我如何使用 EFCore 和 LINQ 实现这一点有任何指导吗？
【问题讨论】：
-
>我的第一个想法是做一个 DTO 这是正确的方法。事实上，我几乎可以说，如果你能提供帮助，你不应该从你的 API 中真正返回 EF 模型（否则每次你更改数据模型时，你的 API 合同可能会在不需要时更改）。
-
啊，谢谢！你绝对是对的，DTO 是最好的方法。
-
您是否尝试过不将
amenity包含为var rooms = await _context.HotelRooms.Where(r => r.HotelID == id).Include(d => d.Room).ThenInclude(a => a.RoomAmenities).ToListAsync();？
标签： c# json linq asp.net-core ef-core-3.0