Question

I have a project that uses an Access DB file for reference tables. This is to be used at work, but I am developing it at home. Up until now, I’ve simply run the debugger in VS2010, then copied the relevant class files, exe, etc from the /bin folder to a flash drive, and it’s worked fine. But with the DB added in, it suddenly crashes on launch.

I know the problem is the file location of the DB file. Originally the Build Action of the DB was sent to Content. I have changed it to Embedded Resource, which as far as I understand means it will be part of the exe file now.

Am I correct in this? If not, what option do I need to select to have the DB become just a compiled part of the exe, or one of the other dll’s?

Answer 1

If the db file is embedded, you can’t access it to add/removes rows etc.
Why did you change the build action to Embedded Resource ? It’ll be better to put as Content, so the db is a separate file than the exe (but still in the same directory), and then build the path to the db file (i.e. using Application.StartupPath).

Anyway, if you want to set it as Embedded you’ll need to extract the db at runtime and store it somewhere before using it.

Here is a method that can extract a file from the embedded resources (of course you’ll need to change the filename, or pass it as argument):

private void ExtractFromAssembly()
{
    string strPath = Application.LocalUserAppDataPath + "\\MyFile.db";
    if (File.Exists(strPath)) return; // already exist, don't overwrite
    Assembly assembly = Assembly.GetExecutingAssembly();
    //In the next line you should provide NameSpace.FileName.Extension that you have embedded
    var input = assembly.GetManifestResourceStream("MyFile.db");
    var output = File.Open(strPath, FileMode.CreateNew);
    CopyStream(input, output);
    input.Dispose();
    output.Dispose();
    System.Diagnostics.Process.Start(strPath);
}

private void CopyStream(Stream input, Stream output)
{
    byte[] buffer = new byte[32768];
    while (true)
    {
        int read = input.Read(buffer, 0, buffer.Length);
        if (read <= 0)
            return;
        output.Write(buffer, 0, read);
    }
}

The file will be copied in the local application path, in the user directory. It’ll be done the first time the app is started, because otherwise the db file will be overwritten each time the application start (overwritten with the clean db package in the exe)