1
我一直在努力DDD幾個月了，雖然我認爲我對某些概念有一個相當不錯的想法，但我對實現應該如何工作不太確定，特別是我該如何應對從數據庫加載數據。這並沒有幫助我只用C＃工作了六個月。域驅動設計中的存儲庫
[原來的問題 - 見下方更新]
在我開始工作的應用程序，我有一個包含基類，執行使用這些基類操作的服務命名空間的域命名空間，並然後存儲庫和DAL命名空間連接到數據庫。
我認爲最簡單的方法是使用服務命名空間中的繼承來添加像LoadFromDb這樣的過程，但是當我開始實現時，我發現這個方法通常需要最多的代碼，因爲我必須將所有類屬性兩次（一次在存儲庫名稱空間中，然後在服務名稱空間中）。
下面是一個例子。我可以選擇2和方案3的工作，但我希望的東西，在精神上更接近選項1
namespace Domain
{
public class Request
{
public int RequestID{get; set;}
public string RequestingUser {get; set;}
public string Title {get; set;}
public string Description{get; set;}
public string status {get; set;}
}
}
namespace app
{
class MyApp
{
void Main()
{
//option 1
Domain.Request x = new Service.svcRequest(5);
//option 2
Domain.Request y = new Service.svcRequest(5);
//option 3
Domain.Request z = new Domain.Request();
Service.svcRequest2.loadRequest(5, z);
}
}
}
namespace Service
{
public class svcRequest : Domain.Request
{
public svcRequest(int RequestID)
{
//this is what I want to do.
// It fails because "this" is read-only
// and because "this" can't be implicitly converted to DomainRequest.
this = (Domain.Request)repos.Loads.LoadRequest(RequestID);
//option 2, which is what I'm doing instead for now, but when you get
// to 20 or 50 properties, it's a bit much,
// esp. since those properties have already been assigned once
// within the repository namespace.
Domain.Request MyRequest = repos.Loads.LoadRequest(RequestID);
this.RequestID = MyRequest.RequestID;
this.RequestingUser = MyRequest.RequestingUser;
this.Title = MyRequest.Title;
this.Description = MyRequest.Description;
this.status = MyRequest.status;
}
}
public class svcRequest2
{
//option 3. Much less code, but now I'm not really using inheritance,
// so in my application layer I can't just declare my variable
// and use the svcRequest constructor
public static void loadRequest(int RequestID, Domain.Request MyRefRequest)
{
MyRefRequest = (Domain.Request)repos.Loads.LoadRequest(RequestID);
}
}
}
namespace repos
{
public static class Loads
{
public static Domain.Request LoadRequest(int RequestID)
{
Domain.Request MyRequest = new Domain.Request();
DataRow MyRow = dal.Loads.LoadRequestRow(RequestID);
MyRequest.RequestID = RequestID;
MyRequest.RequestingUser = (string)MyRow["User"];
MyRequest.Title = (string)MyRow["Title"];
MyRequest.Description = (string)MyRow["Description"];
MyRequest.status = (string)MyRow["Status"];
return MyRequest;
}
}
}
namespace dal
{
public static class Loads
{
public static DataRow LoadRequestRow(int RequestID)
{
OleDbConnection dbCon = new OleDbConnection("Provider=SQLOLEDB;Data Source=dbServer;Initial Catalog=RequestDB;User ID=Joe;Password=password");
string Select = "Select * from RequestTable where ID = " + RequestID;
OleDbDataAdapter dbRequest = new OleDbDataAdapter(Select, dbCon);
DataSet dsRequest = new DataSet();
dbRequest.Fill(dsRequest);
DataRow drRequest = dsRequest.Tables[0].Rows[0];
return drRequest;
}
}
}
[更新] 這裏的第二次嘗試。我將我的Domain名稱空間重命名爲Model，並將我的Service名稱空間重命名爲Domain，我認爲這更符合DDD約定。正如所建議的那樣，我在DAL中使用的存儲庫名稱空間中添加了一個接口。我現在唯一無法工作的是選項1的Load語句，但我認爲我只需要更多地研究繼承。
我靠得更近嗎？
using System;
using System.Data;
using System.Data.OleDb;
namespace Model
{
public class Request
{
public int RequestID{get; set;}
public string RequestingUser {get; set;}
public string Title {get; set;}
public string Description{get; set;}
public string status {get; set;}
}
}
namespace App
{
class MyApp
{
void Main()
{
//option 1
Model.Request x = new Domain.dmnRequest(5);
//option 2
Model.Request y = new Domain.dmnRequest2(5);
//option 3
Model.Request z = new Model.Request();
Domain.dmnRequest3.loadRequest(5, z);
}
}
}
namespace Domain
{
public class dmnRequest : Model.Request, dal.Request
{
public dmnRequest(int requestID)
{
//this is what I want to do. I'm not sure why it's failing
Load(requestID);
}
}
public class dmnRequest2 : Model.Request
{
public dmnRequest2(int requestID)
{
//option 2; it works but is cumbersome after you hit the 20th property
dal.Request tmpRequest = new dal.Request();
tmpRequest.Load(requestID);
this.RequestID = tmpRequest.RequestID;
this.RequestingUser = tmpRequest.RequestingUser;
this.Title = tmpRequest.Title;
this.Description = tmpRequest.Description;
this.status = tmpRequest.status;
}
}
public class dmnRequest3
{
//option 3. Much less code, but now I'm not really using inheritance, so in my application layer I can't just declare my variable and use the dmnRequest constructor
public static void loadRequest(int RequestID, Model.Request MyRequest)
{
dal.Request dalRequest = (dal.Request)MyRequest;
dalRequest.Load(RequestID);
MyRequest = (Model.Request)dalRequest;
}
}
}
namespace repos
{
public interface SaveMe {void Save(int ID); }
public interface LoadMe {void Load(int ID); }
}
namespace dal
{
public class Request : Model.Request, repos.LoadMe
{
public void Load(int requestID)
{
OleDbConnection dbCon = new OleDbConnection("yaddayadda");
string Select = "Select * from RequestTable where ID = " + requestID.ToString();
OleDbDataAdapter dbRequest = new OleDbDataAdapter(Select, dbCon);
DataSet dsRequest = new DataSet();
dbRequest.Fill(dsRequest);
DataRow drRequest = dsRequest.Tables[0].Rows[0];
this.RequestID = requestID;
this.RequestingUser = (string)drRequest["User"];
this.Title = (string)drRequest["Title"];
this.Description = (string)drRequest["Description"];
this.status = (string)drRequest["Status"];
}
}
}
感謝您的回覆。你給了我很多想法。 – Jon