我有錯誤，當客戶名稱或代理人名稱= NULL

Question

和我有錯誤，當客戶名稱或代理人名稱= NULL

var results = db.Users.ToDataSourceResult(request, o => new 
      { 
       Id= o.Id, 
       UserName = o.UserName, 
       Email = o.Email, 
       PhoneNumber = o.PhoneNumber, 
       AgentName = o.Agent.FullName, 
       CustomrName = o.Customer.Name 


      }); 

      return Json(results, JsonRequestBehavior.AllowGet); 

Answer 1

，因爲你試圖訪問一個對象，它是空的財產你得到一個錯誤。代理和客戶屬性在這種情況下。在嘗試使用它們之前，您需要測試空值。

var results = db.Users.ToDataSourceResult(request, o => new 
{ 
    Id = o.Id, 
    UserName = o.UserName, 
    Email = o.Email, 
    PhoneNumber = o.PhoneNumber, 
    AgentName = o.Agent == null ? null : o.Agent.FullName, 
    CustomrName = o.Customer == null ? null : o.Customer.Name 
}); 

return Json(results, JsonRequestBehavior.AllowGet); 

或者，如果你使用的是C＃6你可以使用新的速記

var results = db.Users.ToDataSourceResult(request, o => new 
{ 
    Id = o.Id, 
    UserName = o.UserName, 
    Email = o.Email, 
    PhoneNumber = o.PhoneNumber, 
    AgentName = o.Agent?.FullName, 
    CustomrName = o.Customer?.Name 
}); 

return Json(results, JsonRequestBehavior.AllowGet); 

Answer 2

如果你的意思是你有引用錯誤，這是因爲代理和客戶未在加載用戶類的構造函數，你必須使用延遲加載

Public class user{ 
public user 
(
agent=new Agent(); 
customer=new Customer(); 
) 

} 

Answer 3

我用這個代碼和工作 感謝

var results = db.Users.Include("Customer").Include("Agent").ToDataSourceResult(request, o => new 
      { 
       Id = o.Id, 
       UserName = o.UserName, 
       Email = o.Email, 
       PhoneNumber = o.PhoneNumber, 
       AgentName = o.Agent?.FullName, 
       CustomrName = o.Customer?.Name 


      }); 

      return Json(results, JsonRequestBehavior.AllowGet);