asp.net-mvc - EntityFramework.dll 中发生类型 'System.Data.Entity.ModelConfiguration.ModelValidationException' 的异常

Question

错误 - EntityFramework.dll 中发生“System.Data.Entity.ModelConfiguration.ModelValidationException”类型的异常，但未在用户代码中处理附加信息:在模型生成过程中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“员工”基于没有定义键的类型“员工”。

Controller 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(class):

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

您必须为模型设置属性[Key]，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; }
}

仅当您的数据库生成 ids 时才使用 [DatabaseGenerate(DatabaseGenerateOption.Identity)]，否则您只需使用 [Key] 属性。