創建一個未連接的實體框架DbContext實體

Question

因此，我正在開發一個應用程序，它將從一個數據庫中選擇數據，並根據Authoring數據庫中的「發佈」表中包含的信息更新相同的數據庫。我需要得到一個沒有連接到'創作'上下文的單個對象，所以我可以將它添加到我的'Delivery'上下文中。

目前我使用

object authoringRecordVersion = PublishingFactory.AuthoringContext.Set(recordType.Entity.GetType()).Find(record.RecordId); 
object deliveryRecordVersion = PublishingFactory.DeliveryContext.Set(recordType.Entity.GetType()).Find(record.RecordId)); 

返回我的記錄。然後，如果'deliveryRecordVersion'爲空，我需要在'PublishingFactory.DeliveryContext'中插入'authoringRecordVersion'。但是，該對象已經連接到'PublishingFactory.AuthoringContext'，因此它不會允許在'PublishingFactory.DeliveryContext'上調用Add（）方法。

我有機會獲得PublishingFactory.AuthoringContext.Set(recordType.Entity.GetType()).AsNoTracking()

，但有沒有辦法讓在我從這裏需要的特定記錄。 有什麼建議嗎？

更新：

我相信我找到了解決方案。它第一次沒有工作，因爲我在設置時引用了錯誤的對象.State = EntityState.Detached; 這裏是完整的修正方法，預計

private void PushToDelivery(IEnumerable<Mkl.WebTeam.UWManual.Model.Publication> recordsToPublish) 
    { 
     string recordEntity = string.Empty; 
     DbEntityEntry recordType = null; 

     // Loop through recordsToPublish and see if the record exists in Delivery. If so then 'Update' the record 
     // else 'Add' the record. 
     foreach (var record in recordsToPublish) 
     { 
      if (recordEntity != record.Entity) 
      { 
       recordType = PublishingFactory.DeliveryContext.Entry(ObjectExt.GetEntityOfType(record.Entity)); 
      } 

      if (recordType == null) 
      { 
       continue; 
       ////throw new NullReferenceException(
       //// string.Format("Couldn't identify the object type stored in record.Entity : {0}", record.Entity)); 
      } 

      // get the record from the Authoring context from the appropriate type table 
      object authoringRecordVersion = PublishingFactory.AuthoringContext.Set(recordType.Entity.GetType()).Find(record.RecordId); 

      // get the record from the Delivery context from the appropriate type table 
      object deliveryRecordVersion = PublishingFactory.DeliveryContext.Set(recordType.Entity.GetType()).Find(record.RecordId); 


      // somthing happened and no records were found meeting the Id and Type from the Publication table in the 
      // authoring table 
      if (authoringRecordVersion == null) 
      { 
       continue; 
      } 

      if (deliveryRecordVersion != null) 
      { 
       // update record 
       PublishingFactory.DeliveryContext.Entry(deliveryRecordVersion).CurrentValues.SetValues(authoringRecordVersion); 
       PublishingFactory.DeliveryContext.Entry(deliveryRecordVersion).State = EntityState.Modified; 
       PublishingFactory.DeliveryContext.SaveChanges(); 
      } 
      else 
      { 
       // insert new record 
       PublishingFactory.AuthoringContext.Entry(authoringRecordVersion).State = EntityState.Detached; 

       PublishingFactory.DeliveryContext.Entry(authoringRecordVersion).State = EntityState.Added; 
       PublishingFactory.DeliveryContext.SaveChanges(); 
      } 

      recordEntity = record.Entity; 
     } 
    } 

Answer 1

正如您在您的評論說，爲什麼你不能使用.Single(a => a.ID == record.RecordId)是ID屬性未在設計時知道的原因，工作。所以，你可以做什麼是由Find方法得到實體，然後從上下文脫離它：

PublishingFactory.AuthoringContext 
    .Entry(authoringRecordVersion).State = EntityState.Detached;