How best to deal with dynamic page settings in a C# ASP.NET web application?

Question

I have a single page that has a number of controls configured a certain way depending on some condition (e.g. if it is a user accessing the page or an admin). How I currently achieve this is by having an interface for the settings which are common to all pages, and then extending classes which implement the properties specific to the type of user.

For example:

public interface Display_Type
{
    string backgroundColor { get; }
}

public class AdminPage : Display_Type
{
    string backgroundColor { get { return "orange"; } }
}

public class UserPage : Display_Type
{
    string backgroundColor { get { return "blue"; } }
}

And my page's codebehind:

public partial class MyPage : System.Web.UI.Page
{
    Display_Type pageSettings;

    protected void Page_Load(object sender, EventArgs e)
    {
        if ((bool)Session["Is_Admin"])
        {
            pageSettings = new AdminPage();
        }
        else
        {
            pageSettings = new UserPage();
        }

        // ...

        string backgroundColor = pageSettings.backgroundColor;
        // ... Do stuff with background color
    }
}

This works fine for me, but since these settings are constant across the application, they seem to make more sense as static classes. However, I'm having trouble figuring out how to do this because I can't assign a static class to a variable.

My questions are:

1. Is there a better way I can accomplish what I'm trying to do here?
2. Or, if this is okay, how could I accomplish what I'm doing with static classes / members?

It may be worth noting that the user/admin example is not how I'm using this structure in my web application, and in fact has nothing to do with the user themselves but rather other factors such as request parameters.

Answer 1

To answer your second question, a implementation of a static solution:

public interface IDisplayType
{
    string backgroundColor { get; }
}

public class AdminPage : IDisplayType
{
    public string backgroundColor { get { return "orange"; } }
}

public class UserPage : IDisplayType
{
    public string backgroundColor { get { return "blue"; } }
}

public static class PageProperties
{
    private static AdminPage _adminPage = new AdminPage();
    private static UserPage _userPage = new UserPage();

    public static IDisplayType DisplayType { get
    {
        if ((bool)HttpContext.Current.Session["Is_Admin"])
         {
            return _adminPage;
         }

        return _userPage;
    }
 }

I also changed the type Display_Type to IDisplayType which gives a beter description of what it is.

You could then use the following code in your page.

string backgroundColor = PageProperties.DisplayType.backgroundColor;

Answer 2

1. Is there a better way I can accomplish what I'm trying to do here?

Microsoft .NET has a built-in application settings implementation: setting files. Just use them if your settings aren't configurable by each user.

Application settings can be defined in a satellite assembly and overridden in the app.config or web.config of your application.

That's I find better to define such settings using setting files, which is a built-in, understandable and well-implemented solution and you've it out-of-the-box.

How to accomplish your goal using setting files?

You can use configuration by convention, and your background color settings will look like this:

• AdminPage_BackgroundColor => #000000
• UserPage_BackgroundColor => #FFFFFF
• and so on

In your case, you've two background color settings for both pages, but if you'd need to configure background color for any of pages, you'd do this in your Page-derived class instance:

Properties.PagesStyle.Default[GetType().Name + '_' + "BackgroundColor"]

And you'll be able to get background color by page and from your settings file.

Let's implement this in your page class:

public partial class MyPage : System.Web.UI.Page
{
    Color backgroundColor = null;

    protected void Page_Load(object sender, EventArgs e)
    {
        if ((bool)Session["Is_Admin"])
        {
            backgroundColor = Properties.PagesStyle.Default.AdminPage_BackgroundColor;
        }
        else
        {
            backgroundColor = Properties.PagesStyle.Default.UserPage_BackgroundColor;
        }

        // ... Do stuff with background color
    }
}

Note settings files allow you to define strongly-typed values. Let's say you typed "UserPage_BackgroundColor" as System.Drawing.Color, designer will edit color by using a color picker, and when you access to this setting, you'll get a System.Color instead.

Before begin with another approach, check these useful links:

• Settings files in MSDN: http://msdn.microsoft.com/en-us/library/aa730869(v=vs.80).aspx
• Some other answer I did some time ago: Can a class library have an App.config file?

---

Recommended approach

There's a solid, stable and valuable way of styling Web sites: CSS.

Instead of creating your own styling approach, just play with CSS classes.

For example, in some CSS stylesheet you define both background colors for admin page and user page:

body.UserPage
{
    background-color: #000;
}

body.AdminPage
{
    background-color: #FFF;
}

Just imagine you've this ASP.NET page (I'll include standard XHTML markup only):

<html>
  <head></head>
  <body id="body" runat="server"></body>
</html>

In your code-behind code perhaps you can do this:

public partial class MyPage : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if ((bool)Session["Is_Admin"])
        {
            body.Attributes["class"] = "AdminPage";
        }
        else
        {
            body.Attributes["class"] = "UserPage";
        }
    }
}

This way you avoid:

• Creating redundant settings since you use CSS as styling mechanism (don't reinvent the wheel!).
• Compiling styling values: it's a client-side thing, because it's CSS.

Answer 3

public static class PageTypes {
    public static PageType Admin(/** stuff here */);
    public static PageType User(/** stuff here */);
}

public class PageType {
    readonly string _backgroundColor;
    public PageType (/** stuff here */) {
        _backgroundColor = backgroundColor;
    }

    public string BackgroundColor {
        get {
            return _backgroundColor;
        }
}

So now, you can access them like this in your method:

if ((bool)Session["Is_Admin"])           
{               
    PageSettings = PageTypes.Admin;    
}           
else           
{               
    PageSettings = PageTypes.User;
}

I agree with Jakub about using the base class to prevent code duplication.

Answer 4

You can use a singleton to define your AdminPage and UserPage profile and add a static method GetDisplayType() to your implementation.

Answer 5

This is not how I would do this, but if you are doing it this way, static classes have absolutely nothing to do with and no use in this situation.

You might consider having a single instance of each of the Display_Type classes stored somewhere to be reused, instead of creating a new one each time, though. This might end up being as a static variable... but that's not the same at all as a static class.

Answer 6

Put your settings on the BasePage and have other pages derive from it.

You will set the settings only once.

public abstract class MyBasePage : System.Web.UI.Page
{
    protected Display_Type PageSettings { get; private set; };

    protected void Page_Load(object sender, EventArgs e)
    {
        if ((bool)Session["Is_Admin"])
        {
            PageSettings = new AdminPage();
        }
        else
        {
            PageSettings = new UserPage();
        }
    }
}

public partial class MyPage : MyBasePage
{
    protected void Page_Load(object sender, EventArgs e)
    {
        // ...

        string backgroundColor = PageSettings.backgroundColor;
        // ... Do stuff with background color
    }
}