實體框架System.InvalidOperationException

Question

我在2個不同的類中使用實體框架容器。

private static DataManager instance;
    private Model1Container databaseContainer;
    private DataManager()
    {
        databaseContainer = new Model1Container();
    }

    public static IDataManager Instance
    {
        get
        {
            if (instance == null)
            {
                instance = new DataManager();
            }
            return instance;
        }
    }

    public void OpenNewAccount(int amount)
    {

        Account account = new Account();

        Transaction transaction = new Transaction();
        transaction.Account = account;
        transaction.Amount = amount;
        transaction.Date = DateTime.Now;

        if (TransactionExecutor.Instance.ExecuteTransaction(transaction, account))
        {
            //EXCEPTION An unhandled exception of type                   'System.InvalidOperationException' occurred in System.Data.Entity.dll

            //Additional information: An entity object cannot be referenced by multiple instances of IEntityChangeTracker.
            databaseContainer.Transactions.AddObject(transaction);
            databaseContainer.Accounts.AddObject(account);
            databaseContainer.SaveChanges();
        }
    }

class AccountStateTransactionValidator : AbstractTransactionValidator
{
    override
    public bool HandleTransaction(Transaction transaction, Account account)
    {
        if (account.AccountState == null || (account.Amount < account.AccountState.LeftBound || account.Amount >= account.AccountState.RightBound))
        {
            Model1Container container = new Model1Container();
            AccountState properState = (from st in container.AccountStates
                              where st.LeftBound <= account.Amount &&
                              st.RightBound >= account.Amount
                              select st).FirstOrDefault();
            if (properState != null)
            {
               account.AccountState = properState;
            }
            else
            {
                return false;
            }
        }

        return base.nextTransaction(transaction, account);

    }
}

我得到了這個例外：

 at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
   at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
   at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
   at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()</ExceptionString></Exception></TraceRecord>
An unhandled exception of type 'System.InvalidOperationException' occurred in System.Data.Entity.dll`

我不想修改我的類結構，在這種情況下我可以正確使用Entity Framework嗎？ 怎么樣？

謝謝你的回答。

Answer 1

您正在混合多個數據上下文： account附加到databaseContainer （ databaseContainer.Transactions.AddObject(transaction); account作為來自transaction的嵌套屬性）但來自Model1Container container = new Model1Container(); 。

您不能同時在多個上下文中使用實體實例。

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我也看到了數據容器的某種單例模式，這通常是一個壞的，壞的，壞主意......