C# – How to create a custom attribute that will redirect to Login if it returns false, similar to the Authorize attribute – ASP.NET MVC

.netasp.netasp.net-mvcasp.net-mvc-4c++

I tried Googling a few things about custom attributes but I'm still not sure how to go about it….

I'm storing a few important details of the user in Session cookies (ex UserID) once the user log's in.. and all I want to do is create an attribute where if the

if (Session["UserID"] == null)

then it will redirect to login just like the [Authorize] attribute does. That way I can apply this attribute on the Controller level everywhere.

Should I overwrite the Authorize attribute? Create a new one? How do I get it to redirect to login as well?

I'm also using ASP.NET MVC 4

Thanks for any help

Best Solution

You can create a custom AuthorizeAttribute and override AuthorizeCore() and HandleUnauthorizedRequest() as required. Add your own logic which will do the check and redirect if necessary.

I'm just showing a simple example using MVC's ActionFilterAttribute (which is not the best place to do authentication/authorization)

public class VerifyUserAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        var user = filterContext.HttpContext.Session["UserID"];
        if (user == null)
            filterContext.Result = new RedirectResult(string.Format("/User/Login?targetUrl={0}",filterContext.HttpContext.Request.Url.AbsolutePath));
    }
}

Do not forget to set the Session["UserID"] variable in your /User/Login action method after proper user validation.

Related Solutions

.net – How to redirect to a dynamic login URL in ASP.NET MVC

In the RTM version of ASP.NET MVC, the Cancel property is missing. This code works with ASP.NET MVC RTM:

using System;
using System.Web;
using System.Web.Mvc;
using System.Web.Mvc.Resources;

namespace ePegasus.Web.ActionFilters
{
    public class CustomAuthorize : AuthorizeAttribute
    {
        public override void OnAuthorization(AuthorizationContext filterContext)
        {
            base.OnAuthorization(filterContext);
            if (filterContext.Result is HttpUnauthorizedResult)
            {
                filterContext.Result = new RedirectToRouteResult(
                    new System.Web.Routing.RouteValueDictionary
                        {
                                { "langCode", filterContext.RouteData.Values[ "langCode" ] },
                                { "controller", "Account" },
                                { "action", "Login" },
                                { "ReturnUrl", filterContext.HttpContext.Request.RawUrl }
                        });
            }
        }
    }
}

Edit: You may want to disable the default forms authentication loginUrl in web.config - in case somebody forgets you have a custom attribute and uses the built in [Authorize] attribute by mistake.

Modify the value in web.config:

 <forms loginUrl="~/Account/ERROR" timeout="2880" />

Then make an action method 'ERROR' that logs an error and redirects the user to the most generic login page you have.

C# – How to create a dropdownlist from an enum in ASP.NET MVC

For MVC v5.1 use Html.EnumDropDownListFor

@Html.EnumDropDownListFor(
    x => x.YourEnumField,
    "Select My Type", 
    new { @class = "form-control" })

For MVC v5 use EnumHelper

@Html.DropDownList("MyType", 
   EnumHelper.GetSelectList(typeof(MyType)) , 
   "Select My Type", 
   new { @class = "form-control" })

For MVC 5 and lower

I rolled Rune's answer into an extension method:

namespace MyApp.Common
{
    public static class MyExtensions{
        public static SelectList ToSelectList<TEnum>(this TEnum enumObj)
            where TEnum : struct, IComparable, IFormattable, IConvertible
        {
            var values = from TEnum e in Enum.GetValues(typeof(TEnum))
                select new { Id = e, Name = e.ToString() };
            return new SelectList(values, "Id", "Name", enumObj);
        }
    }
}

This allows you to write:

ViewData["taskStatus"] = task.Status.ToSelectList();

by using MyApp.Common