無法跟蹤實體類型“Entity”的實例，因為已跟蹤另一個具有與 {'Id'} 相同鍵值的實例

Question

我有一個處理查詢並從表中刪除行的方法。

但每次我收到以下錯誤： The instance of entity type 'NotificationQueueEntry' cannot be tracked because another instance with the same key value for {'Id'} is already being tracked.

這是整個方法：

    public static void ProcessQueue()
    {
        var query = _dbContext.Notifications
            .Where(x => x.TransferInterval == TransferIntervalEnum.Instant);
        
        var notificationsToProcess = query.ToList();

        _dbContext.Notifications.RemoveRange(query);
        _dbContext.SaveChanges();
        
        if (!notificationsToProcess.Any())
        {
            return;
        }

        var queue = notificationsToProcess.Select(notification => new MailRequest
        {
            Id = notification.Id,
            MailType = Smtp.MailTypeEnum.HTML,
            MailMessage = new MailMessage
            {
                content = notification.Content.content,
                from = SmtpConfiguration.From, subject = notification.Content.subject,
                to = notification.TransferIdentifier
            }
        }).ToList();

        Smtp.ProcessItems(queue, SmtpConfiguration);
        
    }

錯誤在這一行_dbContext.Notifications.RemoveRange(query);

我該如何解決這個問題？ 我還需要notificationsToProcess變量..

Answer 1

您是否嘗試過 linq 表達式到 select 可用於查詢項目的 ID 列表，然后可能在處理完成后刪除/保存通知