处理实体框架SaveChanges（）异常以进行清理

Question

I have a File Repository library which handles the saving of files onto the server. Along with saving the physical file, a database entry is also recorded .

Below is the insert method.

public DataFile InsertFile(string fileName, byte[] fileBytes)
{
    File.WriteAllBytes(Path.Combine(FileRepPath, fileName), fileBytes);

    DataFile dataFile = NewDataFile(
        fileName,
        fileBytes.Length
    );

    try
    {
        using (MyEntities context = new MyEntities())
        {
            context.DataFiles.Add(dataFile);
            context.SaveChanges();
        }
    }
    catch (Exception)
    {
        File.Delete(Path.Combine(FileRepPath, fileName));
        throw;
    }

    return dataFile;
}

If the database update fails, then I want to delete the file from the server. I do this by catching ANY exception that occurs from the context operations and delete the file (and rethrowing the error so that it can bubble up).

Is this correct practice? Should I be catching more specific exceptions?

Answer 1

I suggest you use the TransactionScope object to manage this task for you. Every component that implements the IEnlistmentNotification interface can participate in a two-phase commit of the TransactionScope .

The commit will require enlisting the services of MS-DTC but it will ensure all or nothing is saved. MS-DTC is used to co-ordinate the results of transactions across multiple heterogeneous resources.

Here are a couple of Microsoft articles:

• Enhance Your Apps With File System Transactions
• Transactional NTFS Managed Wrapper