Handling Entity Framework SaveChanges() exceptions for cleanup

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?

This question asks how to catch all entity framework exceptions. forums.asp.net/t/1829033.aspx/1 — Steven Wexler
– Steven Wexler, Commented May 17, 2013 at 5:48
Be aware that in case of a system failure you might still end up with the file on disk, but not have the record in the database. — Marwijn
– Marwijn, Commented May 17, 2013 at 7:16
In case of a concurrency exception or a unique constraint violation someone else may have added the DataFile just before the current user, so you don't want to delete the file from disk. — Gert Arnold
– Gert Arnold, Commented May 17, 2013 at 8:25

qujck · Accepted Answer · 2013-05-17 08:52:31Z

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:

answered May 17, 2013 at 8:52

qujck

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