EF LINQ查詢收集與渴望加載的子收集

Question

我使用EF4.1代碼首先，

我試圖創建一個查詢返回的集合與渴望加載的子收集。 雙方必須通過位置和IsActive ==真

這些類映射進行排序。

public class Type 
{ 
    public int Id { get; set; } 
    public int AreaId { get; set; } 
    public bool IsActive { get; set; } 
    public int Position { get; set; } 
    ....... 
    public virtual IList<Category> Categories { get; set; } 
} 

public class Category 
{ 
    public int Id { get; set; } 
    public int TypeId { get; set; } 
    public bool IsActive { get; set; } 
    public int Position { get; set; } 
    ....... 
    public virtual Type Type { get; set; } 
} 

的DTO：

public class TypeDTO 
    { 
     public string Name { get; set; } 
     public string UniqueName { get; set; } 
     public virtual IList<CategoryDTO> Categories { get; set; } 
    } 

public class CategoryDTO 
    { 
     public string Name { get; set; } 
     public string UniqueName { get; set; } 

     public virtual TypeDTO Type { get; set; } 
    } 

什麼我有：

隨着DTO：

var result = _db.Types 
          .Where(x => x.IsActive == true) 
          .Where(x => x.AreaId== areaId) 
          .Select(x => new TypeDTO() 
          { 
           Name = x.Name, 
           UniqueName = x.UniqueName, 
           Categories = x.Categories.Where(c => c.IsActive == true) 
                  .OrderBy(c => c.Position) 
                  .Select(c => new CategoryDTO() 
                  { 
                   Name = c.Name, 
                   UniqueName = c.UniqueName 
                  }) 
                  .ToList() 

          }) 
          .ToList(); 

此拋出：

LINQ到恩tities無法識別方法 'System.Collections.Generic.List 1[...CategoryDTO] ToList[...CategoryDTO](System.Collections.Generic.IEnumerable 1 [... CategoryDTO]）' 方法，並且此方法無法轉換爲存儲表達式。

沒有DTO：

var result2 = _db.Categories 
          .Where(x => x.IsActive == true) 
          .OrderBy(x => x.Position) 
          .Select(x => x.Type) 
          .Distinct() 
          .Where(x => x.IsActive == true && x.AreaId== areaId) 
          .OrderBy(x => x.Position) 
          .ToList(); 

它運行沒有錯誤，但並沒有給出正確的結果，並沒有訂購孩子收集

其他不成功的做法：

var result = _db.Types 
          .Where(t => t.IsActive == true) 
          .Where(t => t.SiteId == siteId) 
          .Include(t => t.Categories 
               .Where(c=>c.IsActive == true) 
               .OrderBy(c=>c.Position)) 
          .OrderBy(t => t.Position) 
          .ToList(); 

我錯過了什麼？

謝謝。

編輯 最終的解決方案：

public class TypeDTO 
    { 
     public Type Type { get; set; } 
     public IEnumerable<Category> Categories { get; set; } 
    } 

var result = _db.Types 
       .Where(x => x.IsActive == true) 
       .Where(x => x.AreaId== areaId) 
       .OrderBy(x=>x.Position) 
       .Select(x => new TypeDTO() 
       { 
        Type = x, 
        Categories = x.Categories.Where(c => c.IsActive == true).OrderBy(c => c.Position) 
       }) 
       .ToList(); 

Answer 1

您可以用下面的辦法..

using (var context = new DbContext()) 
{ 
    var activeTypes = context.Types.Where(t => t.IsActive) 
          .Select(t => new 
          { 
           Type= t, 
           ActiveCategories = t.Categories.Where(c => c.IsActive) 
                   .OrderBy(c => c.Position) 
          }).ToList(); 


}