Lambda表达式：如何映射到List而不是IEnumerable？

Question

我使用下面的代码，以避免重复：

private static Expression<Func<Incident_Log, IncidentVM>> mappingIncidentVM() 
     { 
      return x => new IncidentVM 
      { 
       incident_ID = x.incident_id,      
       incident_description = x.incident_description, 
       file_names = x.file_names, 
       location = x.location, 

       Actions = 
        x.Action_Log.Where(y => y.assigned_to == y.assigned_to).Select(z => new ActionVM 
       { 
        incident_ID = z.incident_id, 
        action_ID = z.action_id, 
        action_description = z.action_description 

       })     
       //actionList = new List<ActionVM>(d => mappingActionVM) 

      }; 
     } 

然后，我可以做到以下几点：

List<IncidentVM> incidents = db.Incident_Log.Select(mappingIncidentVM).ToList();

，并将其映射的Incident_Log实体到我的视图模型IncidentVM。 我的问题是，我希望我能直接映射到一个列表，而不是一个IEnumerable.Something这样的：

private static Expression<Func<Incident_Log, IncidentVM>> mappingIncidentVM() 
     { 
      return x => new IncidentVM 
      { 
       incident_ID = x.incident_id,     
       incident_description = x.incident_description, 
       file_names = x.file_names, 
       location = x.location, 

       actionList = 
        x.Action_Log.Where(y => y.assigned_to == y.assigned_to).Select(z => new ActionVM 
        { 
         incident_ID = z.incident_id, 
         action_ID = z.action_id, 
         action_description = z.action_description 

        }).ToList() 


      }; 
     } 

但是，这是抛出一个错误：

LINQ to Entities does not recognize the method System.Collections.Generic.List[ViewModel.ActionVM] ToList[ActionVM](System.Collections.Generic.IEnumerable([ViewModel.ActionVM]) method, and this method cannot be translated into a store expression.

的ToList（）不被认可。

这里是我的ViewModel：

public class IncidentVM 
    { 

     public int incident_ID { set; get; }    

     [Display(Name = "Description*")] 
     [Required] 
     public string incident_description { get; set; } 

     [Display(Name = "Specific Location*")] 
     [Required] 
     public string location { set; get; } 

     public string file_names { set; get; } 

//Here is the problem, I 'd like to have only actionList 
     public IEnumerable<ActionVM> Actions { get; set; }   
     public List<ActionVM> actionList { get; set; } 

这里是为Action_Log对象模型：

public partial class Action_Log 
{ 
    public int action_id { get; set; } 
    public int incident_id { get; set; } 
    public string action_description { get; set; } 

    public virtual Incident_Log Incident_Log { get; set; }  
} 

是否有可能直接映射到在这种情况下，一个列表？

Answer 1

的问题是，LINQ无法翻译ToList所以只是去为IEnumerable，然后在本地处理数据时（已执行查询后）使用ToList，你应该罚款。

Answer 2

尝试

actionList = 
     x.Action_Log.Where(y => y.assigned_to == y.assigned_to).Select(z => new ActionVM 
     { 
      incident_ID = z.incident_id, 
      action_ID = z.action_id, 
      action_description = z.action_description 

     }).ToList<ActionVM>()