LINQ to Entities中只支持无参数构造函数和初始化器？ [英] Only parameterless constructors and initializers are supported in LINQ to Entities?

问题描述

  public class ProductViewModel：IViewModel {
 
 public ProductViewModel（）{
 Categories = new List< CategoryViewModel>（）; 
} 
 
 #region DTO帮助者
 
 public ProductViewModel（Product p）{
 this.ID = p.ID; 
 this.Name = p.Name; 
 this.Price = p.Price; 
 Categories = new List< CategoryViewModel>（）; 
} 
 
 #endregion 
 
 
 public int ID {get;组; } 
 public string Name {get;组; } 
 public decimal价格{get;组; } 
 public IEnumerable< CategoryViewModel>分类{get;组; 
} 
  

我以前用过LINQ2SQL这个代码，使用实体框架它不会：

  var products =（from p in db.GetAll（）
 select new ProductViewModel（p））; 
  

我收到此错误：

  LINQ to Entities中只支持无参数构造函数和初始值设置
  

任何人有帮助解释/解决这个问题？

解决方案

  var products = （from p in db.GetAll（）
选择新的ProductViewModel {
 ID = p.Id，
 .... 
}）; 
  

I have a ProductViewModel that converts a DTO (Product) at runtime.

public class ProductViewModel : IViewModel {

    public ProductViewModel() {
        Categories = new List<CategoryViewModel>();
    }

    #region DTO Helpers

    public ProductViewModel(Product p) {
        this.ID = p.ID;
        this.Name = p.Name;
        this.Price = p.Price;
        Categories = new List<CategoryViewModel>();
    }

    #endregion


    public int ID { get; set; }
    public string Name { get; set; }
    public decimal Price { get; set; }
    public IEnumerable<CategoryViewModel> Categories { get; set; }
}

I've used this code with LINQ2SQL before and it's worked, but now with entity framework it doesn't:

        var products = (from p in db.GetAll()
                        select new ProductViewModel(p));

I get this error:

Only parameterless constructors and initializers are supported in LINQ to Entities

Can anybody help explain/fix this?

解决方案

var products = (from p in db.GetAll()
               select new ProductViewModel{
                   ID = p.Id,
                   ....
               });

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