Question

我目前正在构建基于Web的系统，并尝试在SOA架构中使用DTO实现N层实体框架4.0。我在理解如何实现数据访问层（DAL），业务逻辑层（BLL）和表示层时遇到了问题。

我们假设我有一个“useraccount”实体具有以下内容：

编号

姓

名字

AuditFields_InsertDate

AuditFields_UpdateDate

在DAL中，我创建了一个类“UserAccountsData.cs”，如下所示：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace OrderSystemDAL
{
  public static class UserAccountsData
  {
    public static int Insert(string firstName, string lastName, DateTime insertDate)
    {
      using (OrderSystemEntities db = new OrderSystemEntities())
      {
        return Insert(db, firstName, lastName, insertDate);
      }
    }

    public static int Insert(OrderSystemEntities db, string firstName,
                 string lastName, DateTime insertDate)
    {
      return db.UserAccounts_Insert(firstName, lastName, insertDate, insertDate).ElementAt(0).Value;
    }

    public static void Update(int id, string firstName, string lastName,
                 DateTime updateDate)
    {
      using (OrderSystemEntities db = new OrderSystemEntities())
      {
        Update(db, id, firstName, lastName, updateDate);
      }
    }

    public static void Update(OrderSystemEntities db, int id, string firstName,
                 string lastName, DateTime updateDate)
    {
      db.UserAccounts_Update(id, firstName, lastName, updateDate);
    }

    public static void Delete(int id)
    {
      using (OrderSystemEntities db = new OrderSystemEntities())
      {
        Delete(db, id);
      }
    }

    public static void Delete(OrderSystemEntities db, int id)
    {
      db.UserAccounts_Delete(id);
    }

    public static UserAccount SelectById(int id)
    {
      using (OrderSystemEntities db = new OrderSystemEntities())
      {
        return SelectById(db, id);
      }
    }

    public static UserAccount SelectById(OrderSystemEntities db, int id)
    {
      return db.UserAccounts_SelectById(id).ElementAtOrDefault(0);
    }

    public static List<UserAccount> SelectAll()
    {
      using (OrderSystemEntities db = new OrderSystemEntities())
      {
        return SelectAll(db);
      }
    }

    public static List<UserAccount> SelectAll(OrderSystemEntities db)
    {
      return db.UserAccounts_SelectAll().ToList();
    }
  }
}

在BLL中，我创建了一个类“UserAccountEO.cs”，如下所示：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;
using OrderSystemDAL;

namespace OrderSystemBLL
{
  public class UserAccountEO
  {
    public int Id { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public DateTime InsertDate { get; set; }
    public DateTime UpdateDate { get; set; }

    public string FullName
    {
      get
      {
        return LastName + ", " + FirstName;
      }
    }
    public bool Save(ref ArrayList validationErrors)
    {
      ValidateSave(ref validationErrors);

      if (validationErrors.Count == 0)
      {
        if (Id == 0)
        {
          Id = UserAccountsData.Insert(FirstName, LastName, DateTime.Now);
        }
        else
        {
          UserAccountsData.Update(Id, FirstName, LastName, DateTime.Now);
        }
        return true;
      }
      else
      {
        return false;
      }
    }

    private void ValidateSave(ref ArrayList validationErrors)
    {
      if (FirstName.Trim() == "")
      {
        validationErrors.Add("The First Name is required.");
      }

      if (LastName.Trim() == "")
      {
        validationErrors.Add("The Last Name is required.");
      }
    }
    public void Delete(ref ArrayList validationErrors)
    {
      ValidateDelete(ref validationErrors);

      if (validationErrors.Count == 0)
      {
        UserAccountsData.Delete(Id);
      }
    }

    private void ValidateDelete(ref ArrayList validationErrors)
    {
      //Check for referential integrity.
    }
    public bool Select(int id)
    {
      UserAccount userAccount = UserAccountsData.SelectById(id);

      if (userAccount != null)
      {
        MapData(userAccount);
        return true;
      }
      else
      {
        return false;
      }
    }

    internal void MapData(UserAccount userAccount)
    {
      Id = userAccount.Id;
      FirstName = userAccount.FristName;
      LastName = userAccount.LastName;
      InsertDate = userAccount.AuditFields_InsertDate;
      UpdateDate = userAccount.AuditFields_UpdateDate;
    }
    public static List<UserAccountEO> SelectAll()
    {
      List<UserAccountEO> userAccounts = new List<UserAccountEO>();

      List<UserAccount> userAccountDTOs = UserAccountsData.SelectAll();

      foreach (UserAccount userAccountDTO in userAccountDTOs)
      {
        UserAccountEO userAccountEO = new UserAccountEO();
        userAccountEO.MapData(userAccountDTO);
        userAccounts.Add(userAccountEO);
      }

      return userAccounts;
    }
  }
}

在PL中，我创建了一个网页，如下所示：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using OrderSystemBLL;
using System.Collections;

namespace OrderSystemUI
{
  public partial class Users : System.Web.UI.Page
  {
    protected void Page_Load(object sender, EventArgs e)
    {
      if (!IsPostBack)
      {
        LoadUserDropDownList();
      }
    }
    private void LoadUserDropDownList()
    {
      ddlUsers.DataSource = UserAccountEO.SelectAll();

      ddlUsers.DataTextField = "FullName";
      ddlUsers.DataValueField = "Id";
      ddlUsers.DataBind();
    }

  }
}

以上方式是使用EF4在n层架构中实现DTO模式的正确方法???

感谢您的帮助感谢。

Answer 1

Daniel Simmons发布的网上有一篇很棒的帖子，展示了如何实现N层应用

使用自我实体和DTO实体框架，我认为这会对你有所帮助

http://msdn.microsoft.com/en-us/magazine/3fc94394-227a-4781-a4aa-6ca95ff0107a，并查看

此帖http://msdn.microsoft.com/en-us/magazine/acc3017a-9ec8-4c0e-81e3-db9099e7e4e4

和http://msdn.microsoft.com/en-us/magazine/acc3017a-9ec8-4c0e-81e3-db9099e7e4e4

祝你好运！

Answer 2

DTO应该只有属性，而不是像UserAccountEO这样的方法。您应该将DTO代码与将实体映射到DTO的逻辑分开。

其他一切似乎都是正确的。

BTW：EntitiesToDTOs是一个从您的Entity Framework EDMX文件生成DTO的工具，它可以帮助您节省大量的开发时间和精力。

使用DTO实现N层实体框架4.0

2 个答案: