![](/img/trans.png)
[英]UOW + Repository + Autofac load two different DbContext
[英]UoW and DbContext fail in an event
我已經實現了此Windows服務,該服務使用SendAsync方法每20秒發送一次,每30秒發送一次電子郵件。我正在使用EF6和SQL Server2016。這是代碼的某些部分
EmailRepository.cs
public class EmailRepository : IEmailRepository
{
private BBEntities db = null;
public EmailRepository(BBEntities db)
{
this.db = db;
}
public IEnumerable<tb_Email> SelectAll(int batchAge, int batchSize)
{
DateTime tDate = DateTime.Now.AddMinutes(batchAge);
return db.tb_Email.Where(x => x.ReadyToSend.Equals(true) & x.DateSent.Equals(null) & x.DateCreated >= tDate).OrderBy(x => x.DateCreated).Take(batchSize);
}
public tb_Email SelectByID(Guid id)
{
return db.tb_Email.Find(id);
}
public void Update(tb_Email obj)
{
db.Entry(obj).State = EntityState.Modified;
}
#region IDisposable Support
private bool disposedValue = false;
protected virtual void Dispose(bool disposing)
{
if (!disposedValue)
{
if (disposing)
{
db.Dispose();
}
disposedValue = true;
}
}
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
#endregion
}
UnitOfWork.cs
public class UnitOfWork : IUnitOfWork
{
private readonly BBEntities ctx = new BBEntities();
private IEmailRepository emailRepository;
public IEmailRepository EmailRepository
{
get
{
if (this.emailRepository == null)
{
this.emailRepository = new EmailRepository(ctx);
}
return emailRepository;
}
}
public void Dispose()
{
this.ctx.Dispose();
}
public void Commit()
{
this.ctx.SaveChanges();
}
}
EmailService.cs
public class EmailService : IEmailService
{
private IUnitOfWork unitOfWork;
public EmailService()
{
unitOfWork = new UnitOfWork();
}
public List<tb_Email> SelectAll(int batchAge, int batchSize)
{
return unitOfWork.EmailRepository.SelectAll(batchAge, batchSize).ToList();
}
public tb_Email SelectByID(Guid id)
{
return unitOfWork.EmailRepository.SelectByID(id);
}
public void Update(tb_Email obj)
{
using (unitOfWork = new UnitOfWork())
{
unitOfWork.EmailRepository.Update(obj);
unitOfWork.Commit();
}
}
}
SMTPService.cs
public class SMTPService : ISMTPService
{
SmtpClient client;
MailMessage newMessage;
EmailService emailService;
IEventLoggerService MailCheckerLog;
public SMTPService()
{
emailService = new EmailService();
MailCheckerLog = new EventLoggerService();
}
public void SendEmail(tb_Email email)
{
try
{// rest of the code .....
newMessage = new MailMessage();
newMessage.Headers.Add("X-Email_Id", email.Id.ToString());
client.SendCompleted += (sender, e) => SendCompletedCallback(sender, e);
tb_Email userState = email;
//
// if I put the update database logic here, it works fine
//
client.SendAsync(newMessage, userState);
}
catch (Exception e)
{
MailCheckerLog.log("Error in SendComplete event handler - Exception: " + e.Message.ToString() + " -- InnerException: " + e.InnerException.Message, EventLogEntryType.Error);
client.Dispose();
newMessage.Dispose();
throw;
}
}
void SendCompletedCallback(object sender, System.ComponentModel.AsyncCompletedEventArgs e)
{
tb_Email email = (tb_Email)e.UserState;
Console.WriteLine("----------------------------------" + emailID.Id);
email.ReadyToSend = false;
emailService.Update(email);
client.Dispose();
newMessage.Dispose();
}
}
問題:
因此,要發送和處理電子郵件,我會在一個簡單的循環中使用tb_Email對象的列表運行SendEmail方法,一旦發送了每封電子郵件,我就必須更新數據庫。 為此,我使用
email.ReadyToSend = false;
emailService.Update(email);
在我的SendCompleted事件中,當我使用SendAsync時,系統會繼續處理許多電子郵件,但是對於每個電子郵件,SendCompleted事件可能會在稍后觸發。 為了確保它使用的是唯一的dbContext,我在UoW實例上使用了using語句作為update方法。 如果我將更新邏輯直接放在SendEmail方法中(這沒有任何意義,因為我需要知道電子郵件是否已成功發送),這會很好地工作,但是如果在幾次成功更新后將其放入事件中,它只是拋出
System.Data.Entity.Core.EntityException:“基礎提供程序在打開時失敗。”
我不明白當我實際上為每個操作創建一個新的上下文時怎么可能。
抱歉,我必須自己回答,問題是其他線程仍在使用UoW變量,因此解決方案是在update方法內為using語句聲明一個新變量,如下所示
public class EmailService : IEmailService
{
private IUnitOfWork unitOfWork;
public EmailService()
{
unitOfWork = new UnitOfWork();
}
public List<tb_Email> SelectAll(int batchAge, int batchSize)
{
return unitOfWork.EmailRepository.SelectAll(batchAge, batchSize).ToList();
}
public tb_Email SelectByID(Guid id)
{
return unitOfWork.EmailRepository.SelectByID(id);
}
public void Update(tb_Email obj)
{
IUnitOfWork unitOfWorkUpdate;
using (unitOfWorkUpdate = new UnitOfWork())
{
unitOfWorkUpdate.EmailRepository.Update(obj);
unitOfWorkUpdate.Commit();
}
}
}
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.