How to dynamically add roles to authorize attribute for controller in c#?

To dynamically add roles to authorized controllers in C#, you typically need to implement a custom authorization filter.

Here's a step-by-step guide on how to achieve this:

1. Create a Custom Authorization Filter: First, create a class that implements the IAuthorizationFilter interface. This interface has a method OnAuthorization that gets called before an action method is invoked.
   

   using Microsoft.AspNetCore.Authorization;
   using Microsoft.AspNetCore.Mvc;
   using Microsoft.AspNetCore.Mvc.Filters;
   
   public class DynamicRolesAuthorizationFilter : IAuthorizationFilter
   {
       public void OnAuthorization(AuthorizationFilterContext context)
       {
           // Your logic to dynamically add roles
           var roles = GetDynamicRoles();
   
           var policy = new AuthorizationPolicyBuilder()
               .RequireRole(roles)
               .Build();
   
           var authService = context.HttpContext.RequestServices.GetService(typeof(IAuthorizationService)) as IAuthorizationService;
           var authResult = authService.AuthorizeAsync(context.HttpContext.User, null, policy).GetAwaiter().GetResult();
   
           if (!authResult.Succeeded)
           {
               context.Result = new ForbidResult();
           }
       }
   
       private string[] GetDynamicRoles()
       {
           // Your logic to fetch roles dynamically
           return new string[] { "Admin", "Manager" };
       }
   }
   

2. Apply the Filter to Controllers or Actions: Now, you can apply this filter to your controllers or actions where you want to dynamically add roles.
   

   [TypeFilter(typeof(DynamicRolesAuthorizationFilter))]
   [Authorize]
   public class YourController : Controller
   {
       // Controller actions
   }
   

3. Register the Filter: Finally, make sure you register your custom filter in the ASP.NET Core application's Startup class.
   

   public void ConfigureServices(IServiceCollection services)
   {
       // Other configurations...
   
       services.AddControllersWithViews(options =>
       {
           options.Filters.Add(typeof(DynamicRolesAuthorizationFilter));
       });
   }
   

    

With this setup, every time a request comes to a controller or action decorated with the [Authorize] attribute, the DynamicRolesAuthorizationFilter will be triggered. Inside this filter, you can implement your logic to dynamically determine the roles that are authorized to access the resource.