查詢使用LINQ查詢嵌套對象與加盟

Question

我有我從API得到以下JSON結構：

{ 
    "event_instance": [ 
     { 
      "id": 55551244, 
      "event_id": 11112, 
      "name": "Brown Belt Karate Class", 
      "staff_members": [ 
       { 
        "id": 12345, 
        "name": "John Smith" 
       } 

      ], 

      "people": [ 
       { 
        "id": 111, 
        "name": "Jane Doe" 
       }, 
       { 
        "id": 222, 
        "name": "Josh Smith" 

       }, 
       { 
        "id": 333, 
        "name": "Ben Johnson" 
       } 

      ], 
      "visits": [ 
       { 
        "id": 1234578, 
        "person_id": 111, 
        "state": "completed", 
        "status": "complete" 
       }, 
       { 
        "id": 1239865, 
        "person_id": 222, 
        "state": "completed", 
        "status": "complete" 
       }, 
       { 
        "id": 1239865, 
        "person_id": 333, 
        "state": "canceled", 
        "status": "cancel" 
       } 
      ] 
     } 
    ] 
} 

我使用JSON.NET反序列化到下面的.NET對象是：

[JsonObjectAttribute("event_instance")] 
    public class EventInstance 
    { 
     [JsonPropertyAttribute("id")] 
     public int Id { get; set; } 

     [JsonPropertyAttribute("event_id")] 
     public int EventId { get; set; } 

     [JsonPropertyAttribute("name")] 
     public string Name { get; set; } 

     [JsonPropertyAttribute("staff_members")] 
     public List<StaffMember> StaffMembers { get; set; } 

     [JsonPropertyAttribute("visits")] 
     public List<Visit> Visits { get; set; } 

     [JsonPropertyAttribute("people")] 
     public List<Student> Students { get; set; } 
    } 

    [JsonObjectAttribute("staff_members")] 
    public class StaffMember 
    { 
     [JsonPropertyAttribute("id")] 
     public int Id { get; set; } 
     [JsonPropertyAttribute("name")] 
     public string Name { get; set; } 
    } 

    [JsonObjectAttribute("people")] 
    public class People 
    { 
     [JsonPropertyAttribute("id")] 
     public int Id { get; set; } 
     [JsonPropertyAttribute("name")] 
     public string Name { get; set; } 
    } 

    [JsonObjectAttribute("visits")] 
    public class Visits 
    { 
     [JsonPropertyAttribute("id")] 
     public int Id { get; set; } 
     [JsonPropertyAttribute("person_id")] 
     public int PersonId { get; set; } 
     [JsonPropertyAttribute("state")] 
     public string State { get; set; } 
     [JsonPropertyAttribute("status")] 
     public string Status { get; set; } 
    } 

我使用下面的代碼反序列化：

var event = (EventInstance)JsonConvert.DeserializeObject(json, typeof(EventInstance)); 

以上工作正常，並給了我上述json結構的精確對象表示。現在我試圖查詢這個事件對象來過濾/項目到一個新的結構，然後我可以序列化回json併發送到瀏覽器。我需要返回處於「已完成」狀態和「完成」狀態的活動的學生列表。正如你所看到的，people數組綁定到訪問數組（使用id和person_id）。我想產生以下簡單的輸出：

1. 11112，棕帶空手道班，約翰·史密斯，111，李四
2. 11112，棕帶空手道班，約翰·史密斯，222，約什 - 史密斯

我已經試過這樣的事情：

var studentList = from theClass in event 
        from staff in theClass.StaffMembers 
        from student in theClass.People 
        from visits in theClass.Visits 
        where visits.Status == "complete" 
        && visits.State == "completed" 
          select new 
          { 
           event_id = theClass.EventId 
           class_name = theClass.Name, 
           instructor_name = staff.Name, 
           student_id = student.Id, 
           student_name = student.Name 
          }; 



string _data = JsonConvert.SerializeObject(studentList); 

當然，這會產生重複的學生姓名。我是linq新手。基本上，我需要加入/綁定人員並訪問數組，以便爲​​該ID返回單個學生以及該事件的根數據。任何建議，以更好的方式來做到這一點非常讚賞！

Answer 1

關鍵是要參加的學生和訪問到包含兩個數據集合：

from ei in eventInstances 
from sm in ei.StaffMembers 
from x in 
(from vi in ei.Visits 
join st in ei.Students on vi.PersonId equals st.Id 
select new { vi, st }) // Here you get students and visits side-by-side 
select new 
{ 
    ei.EventId, 
    Event = ei.Name, 
    StaffMemeber = sm.Name, 
    PersonId = x.st.Id, 
    Student = x.st.Name 
}