how implement exiting authentication roles in the database into AspNet IdentityRole - asp.net

Question

i've asp mvc application , database first , i have a table to hold my roles another for my users and junction table user_role.
i added the following class to my app
Microsoft.AspNet.Identity.Owin
Microsoft.AspNet.Identity.EntityFramework
Microsoft.Owin.Host.SystemWeb
can i use my existing tables to apply the roles to my controllers
[Authorize(Roles = "Admin")]]
public ActionResult MySecretAction() {}
or maybe
[Authorize(Roles = MyDBEntities.Roles.Find(1)]]
public ActionResult MySecretAction() {}
thank you

Answer 1

Can I use existing roles from db table?
Yes you can use existing roles from database.
You can use [Authorize(Roles = "Admin")], but not [Authorize(Roles = MyDBEntities.Roles.Find(1)] as it is not constant value, but dynamic.
But how can I add and remove roles to my existing tables when I assign a role to a user?
To add new role(s) you have to use RoleManager class with CreateAsync method along with other methods for managing roles used by your app.
When i add a role to a method , and the user is not authorized to use it , the application redirects him back to the login page ,where to change this?
To alter behavior during athorization you have to implement own Authorization attribute inherited from AuthorizeAttribute and override OnAuthorization method.
public class AuthorizeRoleAttribute : AuthorizeAttribute
{
protected override void HandleUnauthorizedRequest(AuthorizationContext filterContext)
{
// User is not authenticated(NOT logged in)
// we are letting ASP.NET to use standard procedure => redirect her/him to login page
if (!filterContext.HttpContext.User.Identity.IsAuthenticated)
{
base.HandleUnauthorizedRequest(filterContext);
}
// User is authenticated(logged in)
// we are going to show her/him custom view with error
else
{
// Don't forget to create Unauthorized.cshtml view in Shared folder
filterContext.Result = new ViewResult
{
ViewName = "~/Views/Shared/Unauthorized.cshtml"
};
}
}
}
Then you have to use your custom AuthorizeRoleAttribute instead the default one.
[AuthorizeRole(Roles = "Admin")]]
public ActionResult MySecretAction() {}
Resources:
RoleManager class
Implementing RoleManager in ASP.NET MVC 5
ASP.NET MVC 5 Identity: Extending and Modifying Roles

Answer 2

I've created a costume authorization class , witch i can user to access the logged in user and my databases tables
using System;
using System.Web;
using System.Web.Mvc;
using Microsoft.AspNet.Identity;
using System.Linq;
using System.Collections.Generic;
using LoanApp.Models.DataBaseModel;
[AttributeUsage(AttributeTargets.Method | AttributeTargets.Class, Inherited = true, AllowMultiple = true)]
public class DynamicAuthorize : AuthorizeAttribute
{
// public string DefaultURL { get; set; }
protected override bool AuthorizeCore(HttpContextBase context)
{ return true;
}
}