如何使用EF將對象保存到數據庫並獲取從數據庫創建的主鍵？

Question

我正在用C＃，.NET Framework 4.0開發一個WCF JSon Web服務，使用Entity Framework來訪問數據庫。

我必須創建一個新的EReportDB.EReport對象，填充它，將其保存到數據庫並獲得其新的pk EReportDb.Ereport.eReportId。

這是我的代碼，但我不知道如何做到這一點：

public bool SaveEReport(EReportContract eContractReport) 
    { 
     if (eContractReport == null) 
      throw new ArgumentNullException("eContractReport", "SaveEReport: eReport is null"); 

     using (EReportDB.EReportEntities context = new EReportDB.EReportEntities()) 
     { 
      EReportDB.EReport eReport = new EReportDB.EReport(); 
      eReport.orderId = eContractReport.orderId; 
      eReport.timeIn = DateTime.Parse(eContractReport.timeIn, new CultureInfo("en-GB", false)); 
      eReport.timeOut = DateTime.Parse(eContractReport.timeOut, new CultureInfo("en-GB", false)); 
      eReport.isProducFact = eContractReport.isProducFact; 
      /* 
       ..snip.. 
      */ 
      eReport.olPkSizeRs_ = eContractReport.olPkSizeRs; 
      eReport.olPkWeightRs = eContractReport.olPkWeightRs; 
     } 
     return false; 
    } 

我怎麼能這樣做？

Answer 1

int id = 0; // assuming the datatype for eReportId is int 

using (EReportDB.EReportEntities objectContext = new EReportDB.EReportEntities()) 
{ 
    EReportDB.EReport eReport = new EReportDB.EReport(); 
    eReport.orderId = eContractReport.orderId; 
    eReport.timeIn = DateTime.Parse(eContractReport.timeIn, new CultureInfo("en-GB", false)); 
    eReport.timeOut = DateTime.Parse(eContractReport.timeOut, new CultureInfo("en-GB", false)); 
    eReport.isProducFact = eContractReport.isProducFact; 
    /* 
    ..snip.. 
    */ 
    eReport.olPkSizeRs_ = eContractReport.olPkSizeRs; 
    eReport.olPkWeightRs = eContractReport.olPkWeightRs; 

    objectContext.AddObject(eReport); // method to insert the entity 
    objectContext.SaveChanges(); 
    id = eReport.eReportId; 

    transaction.Complete(); 
} 

id是插入記錄的PK。

Answer 2

EF已經爲您填滿了。 只需撥打

context.AddObject(eReport); 
context.Save(); 

你using塊的最後，你會發現在eReport.eReportId您的鑰匙。