LINQ 查詢 orderBy 子查詢

Question

如何使用包含表的 LINQ 查詢按日期排序

    public async Task<IList<TaskSchedule>> GetTask(int id)
    {    
         var taskSchedule = await _context.TaskSchedules
            .Where(u => u.Id == id)
            .Include(ts => ts.Notes.OrderBy(i => i.DateCreated))   //this is what needs to be in ascneding order of date
            .Include(ts => ts.Attachments)
            .Include(c => c.customer)
            .ToListAsync();      
            
        return taskSchedule;  
    }  

下面的代碼有效，但是，它沒有按日期升序整理筆記

   public async Task<IList<TaskSchedule>> GetTask(int id)
    {    
         var taskSchedule = await _context.TaskSchedules
            .Where(u => u.Id == id)
            .Include(ts => ts.Notes)
            .Include(ts => ts.Attachments)
            .Include(c => c.customer)
            .ToListAsync();
       
        return taskSchedule;  
    }  

我收到的錯誤消息是 500（內部服務器錯誤）

System.ArgumentException：類型“System.Linq.IOrderedQueryable 1[Schedular.API.Models.Note]' cannot be used for return type 'System.Linq.IOrderedEnumerable表達式1[Schedular.API.Models.Note]' cannot be used for return type 'System.Linq.IOrderedEnumerable 1[Schedular.API.Models.Note]”

這是我使用工作代碼時返回的 API 數據。 筆記需要按照創建日期的順序排列。 目前，情況正好相反。

[
{
    "id": 102,
    "title": "this should display",
    "start": null,
    "end": null,
    "isClosed": false,
    "highPriority": false,
    "hasTimeLimit": false,
    "customer": null,
    "customerId": null,
    "notes": [
        {
            "id": 70,
            "notesInfo": "add some notes first",
            "dateCreated": "2020-11-17T12:20:00",
            "user": null,
            "userId": 1,
            "taskScheduleId": 102
        },
        {
            "id": 72,
            "notesInfo": "add some notes second",
            "dateCreated": "2020-11-18T16:35:00",
            "user": null,
            "userId": 1,
            "taskScheduleId": 102
        },
        {
            "id": 73,
            "notesInfo": "add some notes third",
            "dateCreated": "2020-11-19T18:35:00",
            "user": null,
            "userId": 1,
            "taskScheduleId": 102
        }
    ],
    "attachments": [],
    "userCurrentAssignedId": 1,
    "userCurrentAssigned": null,
    "userLastEditId": 1,
    "userLastEdit": null,
    "userLastEditDate": "2020-11-19T15:37:00",
    "taskCreatedDate": "2020-11-19T15:37:00"
}

]

Answer 1

總結一下這個問題和評論。

此查詢最初僅受EF Core 5 及更高版本支持。 Include不是子查詢，它是 EF Core 加載相關實體的指令，EF Core 5 中引入了此功能的演變。

無論如何，通常不需要進行此類查詢，因為它們與 DTO 映射相關。 因此，只需手動進行此類映射，此查詢也應適用於 EF Core 3.x。

 var taskSchedule = 
    from ts in await _context.TaskSchedules
    where ts.Id == id
    select new TaskScheduleDTO
    {
        Notes = ts.Notes.OrderBy(n => n.DateCreated).ToList(),
        Attachments = ts.Attachments.ToList(),
        Cutomser = ts.Customer
    }

Answer 2

在Include使用OrderBy是無效的，更改如下：

var taskSchedule = await _context.TaskSchedules
        .Where(u => u.Id == id)
        .Include(ts => ts.Notes)
        .Include(ts => ts.Attachments)
        .Include(c => c.customer)
        .ToListAsync();

taskSchedule.ForEach(t => t.Notes = t.Notes.OrderBy(n => n.DateCreated).ToList());