app settings helper

applicationsettingshelper.cs

public class ApplicationSettingsHelper : IApplicationSettingsHelper
{
    readonly IApplicationSettingRepository _applicationSettingRepository;

    /// <summary>
    /// Default constructor
    /// </summary>
    public ApplicationSettingsHelper(IApplicationSettingRepository applicationSettingsRepository)
    {
        _applicationSettingRepository = applicationSettingsRepository;
    }

    /// <summary>
    /// Returns the raw value (string) of an application setting or null if not set
    /// </summary>
    public string GetSettingValue(ApplicationSettingName settingName, bool throwExceptionNotSet = false)
    {
        var rawValue = GetRawValue(settingName);
        var val = string.IsNullOrWhiteSpace(rawValue) ? null : rawValue;
        if (val == null && throwExceptionNotSet)
            throw new ApplicationException("Application setting: " + settingName.GetDisplayName() + " does not have a value/undefined.");
        return val;
    }

    /// <summary>
    /// Returns a nullable-typed value of an application setting or null if not set (use the string function for strings)
    /// </summary>
    public T? GetSettingValueNullable<T>(ApplicationSettingName settingName) where T : struct
    {
        var rawValue = GetRawValue(settingName);
        return string.IsNullOrWhiteSpace(rawValue) ? null : (T?)Convert.ChangeType(rawValue, (typeof(T).UnderlyingSystemType));
    }
        
    /// <summary>
    /// Returns a typed value of an application setting or the default for the struct if not set (use the string function for strings)
    /// </summary>
    public T GetSettingValue<T>(ApplicationSettingName settingName, bool throwExceptionNotSet = false) where T : struct
    {
        var val = GetSettingValue(settingName);
        return val == null ? new T() : (T)Convert.ChangeType(val, (typeof(T).UnderlyingSystemType));
    }

    private string GetRawValue(ApplicationSettingName settingName)
    {
        var defaultValue = settingName.GetCustomAttribute<DefaultValueAttribute>();
        //Otherwise, look it up in the db
        return _applicationSettingRepository.All().Where(s => s.ApplicationSettingName == settingName).Select(s => s.RawValue).FirstOrDefault()
            ?? (defaultValue == null ? null : defaultValue.Value.ToString());
    }
}

appsetting.cs

/// <summary>
/// Application Level settings within the system.
/// </summary>
public enum ApplicationSettingName
{
    /// <summary>
    /// The time, in seconds, that the S3 Client application has to respond to a request.
    /// </summary>
    [
        Display(
            Name = "Director Request Timeout",
            Description = "The time, in seconds, that the S3 Client application has to respond to a request."),
        DataType(DataType.Custom), // 
        DefaultValue(30)
    ]
    DirectorRequestTimeout = 1,

    /// <summary>
    /// The maximum size of a file chunk (in bytes) that can be pushed to the broker at a given time.
    /// </summary>
    [
        Display(
            Name = "Maximum File Chunk Size",
            Description = "The maximum size of a file chunk (in bytes) that can be pushed to the broker at a given time."),
        DataType(DataType.Custom),
        DefaultValue(1024 * 1024)
    ]
    MaxUploadChunkSize = 2,

    /// <summary>
    /// The timeout, in seconds, that the S3 Client application has to finish uploading a file.
    /// </summary>
    [
        Display(
            Name = "File Upload Request Timeout",
            Description = "The timeout, in seconds, that the S3 Client application has to finish uploading a file."),
        DataType(DataType.Custom),
        DefaultValue(300) // 5 minutes
    ]
    FileUploadRequestTimeout = 3,

    [
        Display(
            Name = "Client Heartbeat Threshold",
            Description = "The number of seconds that a client's heartbeat isn't received from the client before the client is considered as offline."
        ),
        DataType(DataType.Custom),
        DefaultValue(30)
    ]
    ClientHeartbeatThreshold = 4,
}