傳遞分組LINQ對象查看

Question

我試圖從我的控制器傳遞一個LINQ列表對象到我的視圖。 linq對象包含引發某種錯誤的分組。我只想在視圖中顯示分組對象。 linq語句完美地工作，但顯示語句不！任何幫助將不勝感激！

控制器

 public ViewResult StudentAttendanceForYear(int id) 
    { 

     DateTime finDate = System.DateTime.Today; 
     DateTime strtDate = DateTime.Today.AddMonths(-6); 


     var chosenStudent = (from t in db.ClassInstanceDetails.Include("Student") 
           where (t.Attendance == false) && (t.StudentID == id) 
           && (t.ClassInstance.Date > strtDate) && (t.ClassInstance.Date < finDate) 
           group t by new { t.ClassInstance.Date.Year, t.ClassInstance.Date.Month, t.ClassInstance.Date.Day } into grp 
           select new 
           { 

            absentDate = grp.Key, 
            numAbsences = grp.Count(t => t.Attendance == false) 

           }).ToList(); 



     return View(chosenStudent.ToList()); 
    } 

視圖

我試圖改變我的觀點，以

@model IEnumerable<System.Linq.IGrouping<object, FYPSchoolApp.DAL.ClassInstanceDetail>> 

但仍沒有運氣，我不斷收到以下錯誤：

模型項目傳入字典的類型是'System.Collections.Generic.List 1[<>f__AnonymousType7 2 [<> f__AnonymousType6 3[System.Int32,System.Int32,System.Int32],System.Int32]]', but this dictionary requires a model item of type 'System.Collections.Generic.IEnumerable 1 [System.Linq.IGrouping`2 [System.Object，FYPSchoolApp.DAL.ClassInstanceDetail]]'。

Answer 1

不要試圖將匿名類型作爲模型傳遞到視圖中。

你需要的是一個ViewModel：

public class AbsentCountViewModel 
{ 
    public DateTime absentDate { get; set; } 
    public int numAbsences { get; set; } 
} 

然後更改您的查詢，選擇到您的視圖模型

var chosenStudent = 
    (from t in ... 
    group t by new 
    { 
      t.ClassInstance.Date.Year, 
      t.ClassInstance.Date.Month, 
      t.ClassInstance.Date.Day 
    } into grp 
    select new 
    { 
     absentDate = grp.Key, 
     numAbsences = grp.Count(t => t.Attendance == false) 
    }).ToList() 
    // you need to do the select in two steps 
    // because EF cannot translate the new DateTime 
    .Select(item => new AbsenctCountViewModel 
    { 
     absentDate = new DateTime(item.absentDate.Year, 
           item.absentDate.Month, 
           item.absentDate.Day) 
     numAbsences = item.numAbsences 
    }).ToList(); 

return View(chosenStudent); 

終於可以與@model訪問視圖的結果：

@model List<AbsenctCountViewModel>