實體框架 - 如何處理批量SaveChanges失敗

Question

在我的C＃程序中，我使用實體框架將本地SQL Server數據庫與QuickBooks數據同步。從QuickBooks獲取數據似乎沒有任何問題。然而，我在進行實體的批量提交時遇到了一個絆腳石。

目前我正在用可配置數量的實體構建DataContext，然後批量提交實體。到目前爲止批次沒有失敗，但如果它確實如此呢？我想解決這個問題的方法是迭代批處理，並一次提交一個實體，然後記錄導致提交失敗的那個實體。

但是我沒有看到用數據上下文做這件事的方法，因爲它在使用SaveChanges()時似乎是全部或無關緊要的。是否有辦法處理我想要完成的任務，還是應該以完全不同的方式處理故障？

這裏是我目前擁有的代碼，如果你想看看它：

int itemsCount = 0; 
int itemsSynced = 0; 
int itemsFailed = 0; 

ArrayList exceptions = new ArrayList(); 

int batchSliceCount = Properties.Settings.Default.SyncBatchSize; //Getting the max batch size from the settings 
int index = 1; //Index used for keeping track of current batch size on data context 
List<Customer> currentBatch = new List<Customer>(); // List to hold curent batch 

db = new DataContext(DatabaseHelper.GetLocalDatabaseConnectionString()); 

foreach (var customer in QBResponse.customers) 
{ 
    itemsCount++; 

    try 
    { 
     string debugMsg = "Saving Customer with the Following Details....." + Environment.NewLine; 
     debugMsg += "ListId: " + customer.CustomerListId + Environment.NewLine; 
     debugMsg += "FullName: " + customer.FullName + Environment.NewLine; 
     int progressPercentage = (itemsCount * 100)/opResponse.retCount; 
     UpdateStatus(Enums.LogLevel.Debug, debugMsg, progressPercentage); 

     var dbCustomer = db.Customers.FirstOrDefault(x => x.CustomerListId == customer.CustomerListId); 

     if (dbCustomer == null) 
     { 
      // customer.CopyPropertiesFrom(customer, db); 
      Customer newCustomer = new Customer(); 
      newCustomer.CopyCustomer(customer, db); 
      newCustomer.AddBy = Enums.OperationUser.SyncOps; 
      newCustomer.AddDateTime = DateTime.Now; 
      newCustomer.EditedBy = Enums.OperationUser.SyncOps; 
      newCustomer.EditedDateTime = DateTime.Now; 
      newCustomer.SyncStatus = true; 

      db.Customers.Add(newCustomer); 
      currentBatch.Add(newCustomer); 
     } 
     else 
     { 
      //dbCustomer.CopyPropertiesFrom(customer, db); 
      dbCustomer.CopyCustomer(customer, db); 
      dbCustomer.EditedBy = Enums.OperationUser.SyncOps; 
      dbCustomer.EditedDateTime = DateTime.Now; 
      dbCustomer.SyncStatus = true; 
      currentBatch.Add(dbCustomer); 
     } 

     try 
     { 
      if (index % batchSliceCount == 0 || index == opResponse.customers.Count()) //Time to submit the batch 
      { 
       UpdateStatus(Enums.LogLevel.Information, "Saving Batch of " + batchSliceCount + "Customers to Local Database"); 
       db.SaveChanges(); 
       itemsSynced += currentBatch.Count(); 
       currentBatch = new List<Customer>(); 
       db.Dispose(); 
       db = new DataContext(DatabaseHelper.GetLocalDatabaseConnectionString()); 
      } 
     } 
     catch (Exception ex) 
     { 
      string errorMsg = "Error occured submitting batch. Itterating and submitting one at a time. " + Environment.NewLine; 
      errorMsg += "Error Was: " + ex.GetBaseException().Message + Environment.NewLine + "Stack Trace: " + ex.GetBaseException().StackTrace; 
      UpdateStatus(Enums.LogLevel.Debug, errorMsg, progressPercentage); 

      //What to do here? Is there a way to properly iterate over the context and submit a change one at a time? 
     } 
    } 
    catch (Exception ex) 
    { 
     //Log exception and restart the data context 
     db.Dispose(); 
     db = new DataContext(DatabaseHelper.GetLocalDatabaseConnectionString()); 
    } 

    Thread.Sleep(Properties.Settings.Default.SynchronizationSleepTimer); 
    index++; 
} 

Answer 1

這取決於你想從收回的例外......

如果您正在尋找一種方法來重試連接是否中斷，您可以使用自定義執行策略基於DbExecutionStrategy，如果發生特定錯誤，如CodeProject文章中所述，則重試。