how to change the themes in asp.net mvc 2

Question

I would like to have an option wherein a user can choose his theme for the site from the dropdown list and the theme applies to that page [atleast].

I want this to be do

Answer 1

It seems this is not supported out of the box, but here's what I did to implement theming:

First, I Added the App_Themes folder to my project, and set up a couple of themes

I then decided to try and mimic the Web-forms profile provider as close as possible, and added a profile-property to web.config:

<profile>
  <properties>
    <add name="ThemePreference" type="string" defaultValue="Blue" />
  </properties>
</profile>

So, basically what I wanted to do was to be able to load the different css's from the appropriate theme-folder when the theme changed. I did this by implementing a helper method attached to the UrlHelper class so that I could write:

<link href="@Url.Theme("~/Content/Site.css")" rel="stylesheet" type="text/css" />

This should then load the appropriate themed Site.css, and fall back to ~/Content/Site.css if no file was found.

The helper is pretty simple:

public static class UrlHelpers
{
    public static string Theme(this UrlHelper url, string u)
    {
        if (u.StartsWith("~")) u = u.TrimStart('~');
        SettingsProperty settingsProperty = ProfileBase.Properties["ThemePreference"];

        return url.Content("~/App_Themes/"+settingsProperty.DefaultValue + u);
    }
}

Now, in this version of the code it simply gets the default-value, so you'll need to tweak the code slightly. But as you can see, this is not limited to css-files, but works with everything from .master files to images.

Update - Using Session instead of profile

public static class UrlHelpers
{
    public static string Theme(this UrlHelper url, string u)
    {
        if (u.StartsWith("~")) u = u.TrimStart('~');

        object currentThemeName = null;
        if (url.RequestContext.HttpContext.Session != null)
        {
            currentThemeName = url.RequestContext.HttpContext.Session["ThemePreference"];
        }
        return currentThemeName != null ? url.Content(String.Format("~/App_Themes/{0}{1}", currentThemeName, u)) : url.Content("~"+u);
    }
}

The return-line in this method checks if it found a ThemePreference session-value, and then returnes the appropriate URL for the content requested, otherwise it simply returns the content as it was requested with no App_Theme prefix.

In your controlleraction for the DropDown postmethod, you'd simply do:

Session.Add("ThemePreference", whateverValueYouGotFromDropdown);

Update ends

With some tweaking and fixing, this should do the trick.

Hope it helps some, even though it's not a complete walkthrough :)