Action Filter to check Session MVC3 - asp.net-mvc-3

Question

I want to create some custom Filters in my application
After successful login i keep logged in user details in a session and want to check the session is expired or not ( If session expired i want to redirect to login page) and i need a filter for this.
public class MyActionFilterAttribute : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
SchoolApp.ViewModels.CurrentSessionModel model=(SchoolApp.ViewModels.CurrentSessionModel)HttpContext.Current.Session["mySession"];
if (model == null)
{
//Redirect to Login page
}
else
{
base.OnActionExecuting(filterContext);
}
}
}
But the problem is this will fire for every rquests even while loading Login page . So how can i make a useful filter control that check for session

Answer 1

Looks like you're trying to do wrong things there. Check your web.config file - it should have section like:
<authentication mode="Forms">
<forms loginUrl="http://www.your_domain.com/login" name="cookie_name" defaultUrl="default_url" domain="your_domain" enableCrossAppRedirects="true" protection="All" slidingExpiration="true" cookieless="UseCookies" timeout="1440" path="/" />
</authentication>
If your session is expired (cookie with cookie_name non exists anymore) - user will be automatically redirected to loginUrl
If you still want to use filters - there's solution that allows you to exclude global filter for some controllers/actions:
assuming you have method in global.asax.cs:
private static void RegisterGlobalFilters(GlobalFilterCollection filters)
{
IFilterProvider[] providers = FilterProviders.Providers.ToArray();
FilterProviders.Providers.Clear();
FilterProviders.Providers.Add(new ExcludeFilterProvider(providers));
filters.Add(DependencyResolver.Current.GetService<MyFilter>(), 2); // add your global filters here
}
Call it in your global.asax.cs:
RegisterGlobalFilters(GlobalFilters.Filters);
Filter provider class will look like:
public class ExcludeFilterProvider : IFilterProvider
{
private readonly FilterProviderCollection _filterProviders;
public ExcludeFilterProvider(IFilterProvider[] filters)
{
_filterProviders = new FilterProviderCollection(filters);
}
public IEnumerable<Filter> GetFilters(ControllerContext controllerContext, ActionDescriptor actionDescriptor)
{
Filter[] filters = _filterProviders.GetFilters(controllerContext, actionDescriptor).ToArray();
if (filters.Select(f => f.Instance).OfType<OverrideExcludeFilter>().Any())
return filters;
IEnumerable<ExcludeFilterAttribute> excludeFilters = (from f in filters where f.Instance is ExcludeFilterAttribute select f.Instance as ExcludeFilterAttribute);
var excludeFilterAttributes = excludeFilters as ExcludeFilterAttribute[] ?? excludeFilters.ToArray();
if (excludeFilterAttributes.FirstOrDefault(f => f.AllFilters) != null)
{
return new Collection<Filter>();
}
var filterTypesToRemove = excludeFilterAttributes.SelectMany(excludeFilter => excludeFilter.FilterTypes);
IEnumerable<Filter> res = (from filter in filters where !filterTypesToRemove.Contains(filter.Instance.GetType()) select filter);
return res;
}
}
ExcludeFilter attribute class:
public class ExcludeFilterAttribute : FilterAttribute
{
private readonly Type[] _filterType;
public ExcludeFilterAttribute(bool allFilters)
{
AllFilters = allFilters;
}
public ExcludeFilterAttribute(params Type[] filterType)
{
_filterType = filterType;
}
/// <summary>
/// exclude all filters
/// </summary>
public bool AllFilters { get; private set; }
public Type[] FilterTypes
{
get
{
return _filterType;
}
}
}
And usage sample:
[ExcludeFilter(new[] { typeof(MyFilter) })]
public ActionResult MyAction()
{
//some codes
}
So this way your filter of type MyFilter won't fire for specified action