实体框架代码第一计算属性 [英] Entity Framework Code First Computed Properties

问题描述

我在ASP.NET MVC 3 Web应用程序中使用了Entity FrameworkCode First方法。在我的数据库中，我有几个计算列。我需要使用这些列来显示数据（可以正常工作）。

但是，当我在这个表中插入行时，我收到以下错误： / p>

列ChargePointText不能修改
，因为它是
计算列，或者是
UNION运算符

有没有办法在我的课程中将属性标记为只读方式？

  public class Tariff 
 {
 public int TariffId {get;组; } 
 public int Seq {get;组; } 
 public int TariffType {get;组; } 
 public int TariffValue {get;组; } 
 public string标题{get;组; } 
 public string描述{get;组; } 
 public int ChargePoint {get;组; } 
 public string ChargePointText {get;组; } 
} 
  

解决方案

解。实体框架提供了一个名为DatabaseGenerated的数据注释。使用它像这样：

  [DatabaseGenerated（DatabaseGeneratedOption.Computed）] 
 public string ChargePointText {get;组; 
  

获取更多详细信息： http://msdn.microsoft.com/en-us/library/gg193958.aspx

I'm using Entity Framework "Code First" approach in a ASP.NET MVC 3 web application. In my database I have several computed columns. I need to use these columns to display data (which works fine).

However when I come to insert rows into this table, I'm getting the following error:

The column "ChargePointText" cannot be modified because it is either a computed column or is the result of a UNION operator.

Is there a way to mark the property as readonly in my class?

public class Tariff
{
    public int TariffId { get; set; }
    public int Seq { get; set; }
    public int TariffType { get; set; }
    public int TariffValue { get; set; }
    public string Title { get; set; }
    public string Description { get; set; }
    public int ChargePoint { get; set; }
    public string ChargePointText { get; set; }
}

解决方案

I've found the solution. Entity Framework provides a data annotation called DatabaseGenerated. Use it like this:

[DatabaseGenerated(DatabaseGeneratedOption.Computed)]
public string ChargePointText { get; set; }

Get more details here: http://msdn.microsoft.com/en-us/library/gg193958.aspx

这篇关于实体框架代码第一计算属性的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！