EntityFramework.dll中出现'System.Data.Entity.ModelConfiguration.ModelValidationException'类型的异常

Question

错误 - 在EntityFramework.dll中发生类型'System.Data.Entity.ModelConfiguration.ModelValidationException'的异常,但未在用户代码中处理其他信息:在模型生成期间检测到一个或多个验证错误:MVCApplication.Models.Employee :: EntityType"Employee"没有定义键.定义此EntityType的键.员工:EntityType:EntitySet'Employees'基于类型'Employee',没有定义键.

控制器代码:

namespace MVCApplication.Controllers
{
    public class EmployeeController : Controller
    {
        // GET: Employee
        public ActionResult Detail(int id)
        {
            EmployeeContext employeecontext = new EmployeeContext();
            Employee emp = employeecontext.Employees.Single(x => x.Emp_Id ==id);//here its throwing an exception
            return View("employee",emp);
        }
    }

这是我的模范员工类:

namespace MVCApplication.Models
{
    [Table("Employee")]
    public class Employee
    {
        public int Emp_Id { get; set; }
        public string Emp_Name { get; set; }
        public string Designation { get; set; }
        public string City { get; set; }
        public string State { get; set; }
        public string Country { get; set; }
    }
}

这是我的员工上下文类:

namespace MVCApplication.Models
{
    public class EmployeeContext : DbContext
    {
        public DbSet<Employee> Employees { get; set; }
    }
}

Answer 1

您必须将属性设置[Key]为模型,如下所示

[Table("Employee")]
public class Employee
{
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    [Key]
    public int Emp_Id { get; set; }
    public string Emp_Name { get; set; }
    public string Designation { get; set; }
    public string City { get; set; }
    public string State { get; set; }
    public string Country { get; set; }
}

使用[DatabaseGenerated(DatabaseGeneratedOption.Identity)]只有当你的数据库生成的ID,如果你不只是[Key]属性.