Can i use Linq to iterate/filter my web.config AppSettings?

Question

i'm trying to figure out how I can use Linq to filter out some of my appsettings from my web.config file.

i'm trying to do something like the following (which has wrong syntax) :-

var query = from q in System.Web.Configuration.WebConfigurationManager.AppSettings.Keys
            where q.StartsWith("Foo")
            select q);

what have I done wrong?

edit: added screenie (here's a link to it)

alt text http://img21.imageshack.us/img21/5516/errorji.png

Answer 1

Try this if you want the values:

var settings = System.Web.Configuration.WebConfigurationManager.AppSettings;

var query = from string q in settings.Keys
            where q.StartsWith("Foo")
            select settings[q];

Answer 2

Could be because KeysCollection only implements IEnumerable not IEnumerable<T>. Try using the Cast method on the Keys property first, something like:

var query = from q in System.Web.Configuration.WebConfigurationManager.AppSettings.Keys.Cast<string>()
        where q.StartsWith("Foo")
        select q;