How should I create a user preference attribute?

Question

In my current asp.net mvc project a user should be able to log in. When logged in a set of preferences can optionally be set. Some of those preferences are general (e.g. prefered site language etc), but some are specific to this project only (pre-defined query filtering etc).

Since these preferences are present in a lot of different places of my site I would define this as cross-concern. Preferably I would have an attribute handle this rather than every action on it's own.

How can I design such an attribute that is generic enough to re-use in future projects yet knows enough about the current project to use all the project specific settings too?

--EDIT--
Getting and setting the preferences is not the problem. I connected a UserSettings class to the asp.net profile provider. My problem is how to pull this cross concern out of my controllers into an attribute.

Answer 1

independently if you are storing that preferences in a text file, xml or database, wouldn't be easier to create a class (for example Utility.UserPreferences) that will load those preferences from the user and store them in a Session variable, then using an enum call them to retrieve / update

namespace Utility
{
    public class UserPreferences
    {
        public UserPreferences(int userID)
        {
            // Load Preferences from text file, xml file or DB
            string loadedPreferences = "us|20|yes|no";

            HttpContext.Current.Session["userPreferences"] = loadedPreferences;
        }

        public void Savepreferences(string[] pref, int userID)
        { 
            // Save preferences for that user
        }

        public static string GetPreferences(PreferencesType type)
        {
            string[] pref = HttpContext.Current.Session["userPreferences"].ToString().Split('|');

            switch (type)
            {
                case PreferencesType.Language: return pref[0];
                case PreferencesType.ShowHowManyResults: return pref[1];
                case PreferencesType.ShowNavigation: return pref[2];
                case PreferencesType.GetEmailAlerts: return pref[3];
            }
        }

        public enum PreferencesType
        {
            Language, ShowHowManyResults, ShowNavigation, GetEmailAlerts
        }
    }
}

then ...

// Login sucessfully...
Utility.UserPreferences pref = new Utility.UserPreferences(CurrentUser.ID);


// to retrieve a preference
string language = Utility.UserPreferences.GetPreferences(
                        Utility.UserPreferences.PreferencesType.Language,
                        CurrentUser.ID);

it's just an idea... the way I would do it... it's simple and it's project(s) wide, cause you just need to change the class to hold more preferences...

Answer 2

For user preferences you should use the ASP.NET Profile Provider framework. Some resources:

• ASP.NET Profile Providers
• Implementing a Profile Provider
• StackOverflow: Implementing Profile Provider in ASP.NET MVC
• StackOverflow: Implementing a Custom Profile Provider in ASP.NET MVC

You could build attribute-based user preference handling on top of the Profile provider framework, but I imagine that sort of thing would be specific to your app.