C# Configuration Files

Question

Okay, so a while ahead I posted how to read other config files of other programs (here is the link Previous Post. I managed to do it. But now there is another problem. The scenario is like this, I have two programs. Program A reads its configuration from a config file and program B is only used to modify the contents of the config file which A reads. The name of the config file is email.config. It is in the same directory in which program A & B resides.

The problem is that I get path of a file for attachment using open file dialog. If the path points to a file in the same directory, the program works perfect! But if it points to a file outside the directory it throws an exception of type System.NullReferenceException.

Here is the code

private void saveBtn_Click(object sender, EventArgs e)
{
    try
    {
        // save everything and close
        string attachment = attachTxtBox.Text;

        var configMap = new ExeConfigurationFileMap { ExeConfigFilename = configFileName };
        // it throws exception here when
        // the path points to a file outside the exes directory
        Configuration externalConfig = ConfigurationManager.OpenMappedExeConfiguration(configMap, ConfigurationUserLevel.None);

        externalConfig.AppSettings.Settings["ServerAddress"].Value = serverAddr;
        externalConfig.AppSettings.Settings["Port"].Value = port;
        externalConfig.AppSettings.Settings["SSL"].Value = ssl.ToString();
        externalConfig.AppSettings.Settings["Sender"].Value = senderAddr;
        externalConfig.AppSettings.Settings["SenderPassword"].Value = password;
        externalConfig.AppSettings.Settings["Subject"].Value = subject;
        externalConfig.AppSettings.Settings["AttachmentPath"].Value = attachment;
        externalConfig.AppSettings.Settings["Body"].Value = messageBody;

        // Save values in config
        externalConfig.Save(ConfigurationSaveMode.Full);
        Application.Exit();
    }
    catch (System.Exception ex)
    {
        MessageBox.Show("Error: " + ex.Message);
        Application.Exit();
    }
}

The content of email.config is:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <appSettings file="">
    <clear />
    <add key="ServerAddress" value="" />
    <add key="Port" value="" />
    <add key="Sender" value="" />
    <add key="SenderPassword" value="" />
    <add key="Subject" value="" />
    <add key="AttachmentPath" value="" />
    <add key="Body" value="" />
  </appSettings>
</configuration>

What am I doing wrong here?

EDIT: The value of configFileName is "email.config"

Answer 1

Well, I figured it out myself after debugging for almost 5 hours, Damn!

The problem was when I used OpenFileDialog to get the file path, it changed the current directory to the one which is selected in the dialog, so the program couldn't find the config file. All I did was to set the RestoreDirectory property of OpenFileDialog to true and poof it worked

Thanks everyone, ChrisF, Eoin Campbell and pablito.

Answer 2

Are you accessing the file by its full path or just the file name?

If the latter then this will work when the file is in the same folder as the executable, but not otherwise.

UPDATE

It looks as though things are more complicated than I first thought and this doesn't seem to be the issue here - see the comments. The line that's raising the exception is:

externalConfig.AppSettings.Settings["ServerAddress"].Value = serverAddr;

So that means that there's a null reference somewhere along the chain. If you can identify which it is then that should give you a pointer to the problem.