Entity Framework Foreach 循环中的事务

Question

我正在尝试使用 Entity framework 从 Windows Forms DataGridView 中保存数据。由于某种原因，记录不会保存到数据库中。我想遍历 DataGridView 并将每一行添加到一个事务对象中，并将所有事务（行）一次保存到数据库中。

我在交易中找到的信息来自 MSDN. While searching for a solution to the problem I came across this SO post，其中有一条评论显示 "I'm taking an exception to trapping the exception like this. It causes the database operation to fail silently." 这似乎是我的代码中发生的事情。我没有收到任何错误，它只是没有将任何内容保存到数据库中。

如何自动保存所有事务并在出现故障时回滚？我如何重新组织事物以正确捕获错误？如果注释正确，MSDN 的代码有什么问题？

这是我的代码：

// Store the valid transactions
using ( var dbContextTransaction = context.Database.BeginTransaction() )
{
    try
    {
        Transaction oTransaction = new Transaction();

        foreach ( DataGridViewRow row in dgvInventoryTransactions.Rows )
        {
            if ( !row.IsNewRow )
            {
                // Get the product
                int iSelectedProduct = int.Parse( row.Cells[0].Value.ToString() );
                oTransaction.Product = context.Products.First( p => p.ID == iSelectedProduct );

                // Quantities
                oTransaction.FullQuantity = int.Parse( row.Cells[1].Value.ToString() );
                oTransaction.PartialQuantity = int.Parse( row.Cells[2].Value.ToString() );
                oTransaction.CalculatedQuantity = (double)oTransaction.FullQuantity + ( (double)oTransaction.PartialQuantity / (double)oTransaction.Product.Pieces );

                // Check to see if a truck has been selected
                if ( !string.IsNullOrEmpty( row.Cells[3].FormattedValue as String ) )
                {
                    // A truck has been selected
                    int iSelectedVehicle;
                    if ( int.TryParse( row.Cells[3].FormattedValue.ToString(), out iSelectedVehicle ) )
                    {
                        oTransaction.Vehicle = context.Vehicles.Where( v => v.VehicleNumber == iSelectedVehicle ).First();
                    }

                }

                // Check to see if the "Source" field contains data
                if ( !string.IsNullOrEmpty( row.Cells[4].FormattedValue as String ) )
                {
                    oTransaction.SourceNumber = row.Cells[4].Value.ToString();
                }

                // Check to see if the comments field contains data
                if ( !string.IsNullOrEmpty( row.Cells[5].FormattedValue as String ) )
                {
                    oTransaction.Comments = row.Cells[5].Value.ToString();
                }

                // Get the transaction type
                int value = int.Parse( cmboTransactionType.SelectedValue.ToString() );
                oTransaction.TransactionType = context.TransactionTypes.Where( t => t.ID == value ).First();

                // Get the current user
                var user = context.Employees.First( u => u.ID == Globals.User ); // One lookup...
                oTransaction.CreatedBy = user;
                oTransaction.LastUpdatedBy = user;                                     

                // Add the dates
                oTransaction.TransactionDate = dtpTransactionDate.Value;
                oTransaction.CreateDate = DateTime.Now;
                oTransaction.LastUpdatedDate = DateTime.Now;

                // Save the transaction
                context.SaveChanges();


            }

        }

        // Commit the changes to the database
        dbContextTransaction.Commit();

    }
    catch ( Exception )
    {
        dbContextTransaction.Rollback();
        MessageBox.Show( "Records were NOT saved successfully.", "Save Unsuccessful", MessageBoxButtons.OK, MessageBoxIcon.Information );
    }

}

Answer 1

您尚未插入 oTransaction 或将其连接到某个现有对象。 EF 不知道这个对象存在。尝试使用 AddObject 方法添加交易。这会将其注册到 EF.

此外，您可以删除 Rollback 调用。它在没有提交时回滚。也将消息框移出using块以快速结束事务。

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