在 Visual Studio 2015 中添加视图时出错

Question

所以我在我的应用程序中使用这些类。

 public class Expenses
 {
    public Category Category { get; set; }
    public PaymentModes PaymentModes { get; set; }
 }

 public class Category 
 {
    public int CategoryID { get; set; }
    public string CategoryName { get; set; }
 }

public class PaymentModes
 {
    public int PaymentModeID { get; set; }
    public string PaymentMode { get; set; }
 }

现在，当我在 Details 方法中添加视图时，它抛出以下错误。

 public ActionResult Details(int id)
 {
    return View();
 }

我该怎么办？

Answer 1

查看错误信息。它清楚地表明您没有为 PaymentModes 和 Expenses 模型类定义主键。请把你的三个型号类写成如下：

public class Category 
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int CategoryID { get; set; }
    public string CategoryName { get; set; }
}

public class PaymentModes
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int PaymentModeID { get; set; }
    public string PaymentMode { get; set; }
}

public class Expenses
{
     [Key, ForeignKey("Category"),Column(Order = 0)]
     public int CategoryID { get; set; }

     [Key, ForeignKey("PaymentModes"),Column(Order = 1)]
     public int PaymentModeID { get; set; }

     public Category Category { get; set; }

     public PaymentModes PaymentModes { get; set; }

}

在 Visual Studio 2015 中添加视图时出错

Error occoured while adding view in Visual Studio 2015

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