What is correct approach to handle parameters read from config file?

Question

I have an application that uses App.config file to store parameters used throughout the application. The parameters represent file names, paths and similar.

The main call looks as following:

CsvExtractor.ExtractDataAndCopyFiles();

...

public class CsvExtractor
{
    public static void ExtractDataAndCopyFiles()
    {
        var eventList = DataReader.ReadInputCsvFile(ExtractorParams.InputCsvFile, ExtractorParams.SheetName);
        DataWriter.WriteOutputCsvFile(
            ExtractorParams.OutputCsvFile,
            CreateExtractData(eventList),
            ExtractorParams.EventFolder,
            ExtractorParams.BlobFolder,
            ExtractorParams.MissingFiles);
    }

    ...
}

What is correct approach:

1) Use the separate class as following:

public class ExtractorParams
{
    public static string InputCsvFile
    {
        get { return ConfigurationManager.AppSettings["InputCsvFile"]; }
    }

    public static string SheetName
    {
        get { return ConfigurationManager.AppSettings["SheetName"]; }
    }

    public static string EventFolder
    {
        get { return ConfigurationManager.AppSettings["EventFolder"]; }
    }

    public static string BlobFolder
    {
        get { return ConfigurationManager.AppSettings["BlobFolder"]; }
    }

    public static string OutputCsvFile
    {
        get { return ConfigurationManager.AppSettings["OutputCsvFile"]; }
    }

    public static string MissingFiles
    {
        get { return ConfigurationManager.AppSettings["MissingFiles"]; }
    }
}

And use it when needed as above.

Or:

2) Use the array of parameters as following:

CsvExtractor.ExtractDataAndCopyFiles(list_of_params);

...

public class CsvExtractor
{
    public static void ExtractDataAndCopyFiles(params string[] list)
    {
        ...
    }

    ...
}

Answer 1

option 1) +1 But in my project we did something like this

public class AppSettingsManager : IAppSettingsManager
{
    private static string filesFolder;

    public static string FilesFolder
    {
        get
        {
            if (filesFolder == null)
            {
                filesFolder = filesFolder = ConfigurationManager.AppSettings["FilesFolder"];
            }

            return filesFolder;
        }
    }
}

we saved a value from config file in the static variable. when it needed we get it from this variable.

Answer 2

I like to do option 1) but with a little twitch.

Create a model that should contain the settings:

public class CsvConfig
{
    public string Opt1 { get; set; }
    public string Opt2 { get; set; }
    //....
}

Loader

public class Config
{
    public CvsConfig Csv { get; private set; }

    public Config()
    {
         Csv = new CsvConfig
         {
             // load stuff from where ever
         }
    }
}

By separating the config model and population of it will decouple the fact that you are using the app.config for settings. This is useful when thinking about test etc. This of course only works if you don't use static stuff, but a more Dependency Injection approach.