实体框架：获取存储库中的子类对象 [英] Entity Framework: Get Subclass objects in Repository

问题描述

我有以下列出的数据库表中的以下模型。

I have following model corresponding to the database tables listed below.

经理是一名员工。会计师也是一名员工。

A manager is an employee. An accountant also is an employee.

1. 在存储库中获取所有管理员的最佳方法是什么？如何实现GetAllManagers（）方法？


2. TPT是否正确？

代码

MyRepository.MyEmployeeRepository rep = new MyEmployeeRepository();
List<Employee> e = rep.GetAllEmployees();



public class MyEmployeeRepository
{
    private string connectionStringVal;
    public MyEmployeeRepository()
    {
        SqlConnectionStringBuilder sqlBuilder = new SqlConnectionStringBuilder();
        sqlBuilder.DataSource = ".";
        sqlBuilder.InitialCatalog = "LibraryReservationSystem";
        sqlBuilder.IntegratedSecurity = true;

        // Initialize the EntityConnectionStringBuilder.
        EntityConnectionStringBuilder entityBuilder = new EntityConnectionStringBuilder();
        entityBuilder.Provider = "System.Data.SqlClient";
        entityBuilder.ProviderConnectionString = sqlBuilder.ToString();
        entityBuilder.Metadata = @"res://*/Test.csdl|res://*/Test.ssdl|res://*/Test.msl";

        connectionStringVal = entityBuilder.ToString();


    }


    public List<Employee> GetAllEmployees()
    {

        List<Employee> employees = new List<Employee>();
        using (var context = new MyEntityDataModelEDM.LibraryReservationSystemEntities1(connectionStringVal))
        {
            foreach (MyEntityDataModelEDM.Employee p in context.Employees)
            {
                employees.Add(p);
            }
        }

        return employees;
    }

    public List<Manager> GetAllManagers()
    {

        List<Manager> managers = new List<Manager>();
        using (var context = new MyEntityDataModelEDM.LibraryReservationSystemEntities1(connectionStringVal))
        {


        }

        return managers;
    }



}

编辑

此模型有缺点。应该考虑以下内容：

This model has drawbacks. It should consider following:

1. 员工可以创建，没有任何角色。


2. 可以有多个角色。

推荐答案

只需执行：

return context.Employees.OfType<Accountant>().ToList()

然而，这是模拟员工的一个非常糟糕的方法..如果会计师改变工作，您需要杀死并重新创建该对象。

This is however a really bad way to model employees.. if an accountant changes job, you need to kill and recreate that object..

请参阅我的答案关于继承与枚举属性域模型。

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