Initializing roles in .NET 8 Blazor web app

Question

I am trying to initialize roles for my Blazor app. This is my service that should create roles if they don't exist:

using Microsoft.AspNetCore.Identity;

namespace FoodApp.Services
{
    public class RoleInitializerService : IHostedService
    {
        private readonly RoleManager<IdentityRole> _roleManager;

        public RoleInitializerService(RoleManager<IdentityRole> roleManager)
        {
            _roleManager = roleManager;
        }

        public async Task StartAsync(CancellationToken cancellationToken)
        {
            string[] roles = { "Administrator", "User" };

            foreach (var role in roles)
            {
                if (!await _roleManager.RoleExistsAsync(role))
                {
                    await _roleManager.CreateAsync(new IdentityRole(role));
                }
            }
        }

        public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
    }
}

And this is service registration in program.cs

builder.Services.AddScoped<RoleInitializerService>();

I put a breakpoint inside the StartAsync method of my service, and the method was never executed.

What am I doing wrong? Is the problem laying in lifetime mismatch or what else?

builder.Services.AddHostedService<RoleInitializerService>(); — GH DevOps
– GH DevOps, Commented Jul 2, 2024 at 13:05
@GHDevOps InvalidOperationException: Cannot consume scoped service 'Microsoft.AspNetCore.Identity.RoleManager`1[Microsoft.AspNetCore.Identity.IdentityRole]' from singleton 'Microsoft.Extensions.Hosting.IHostedService'. — Tomm
– Tomm, Commented Jul 2, 2024 at 15:19
It can't be scoped. Remove the registration and use the AddHostedService middleware only. — GH DevOps
– GH DevOps, Commented Jul 2, 2024 at 15:33

Jalpa Panchal · Accepted Answer · 2024-07-10 06:58:25Z

0

You could try this code:

 using Microsoft.AspNetCore.Identity;

namespace FoodApp.Services
{
    public class RoleInitializer
    {
        private readonly RoleManager<IdentityRole> _roleManager;

        public RoleInitializer(RoleManager<IdentityRole> roleManager)
        {
            _roleManager = roleManager;
        }

        public async Task InitializeRolesAsync()
        {
            string[] roles = { "Administrator", "User" };

            foreach (var role in roles)
            {
                if (!await _roleManager.RoleExistsAsync(role))
                {
                    await _roleManager.CreateAsync(new IdentityRole(role));
                }
            }
        }
    }
}

Program.cs:

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddControllersWithViews();

// Register RoleManager and Identity services
builder.Services.AddIdentity<IdentityUser, IdentityRole>()
    .AddEntityFrameworkStores<ApplicationDbContext>()
    .AddDefaultTokenProviders();

// Register the RoleInitializer service
builder.Services.AddScoped<RoleInitializer>();

var app = builder.Build();

// Configure the HTTP request pipeline.
if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Home/Error");
    app.UseHsts();
}

app.UseHttpsRedirection();
app.UseStaticFiles();

app.UseRouting();

app.UseAuthentication();
app.UseAuthorization();

app.MapControllerRoute(
    name: "default",
    pattern: "{controller=Home}/{action=Index}/{id?}");

// Call the RoleInitializer during application startup
using (var scope = app.Services.CreateScope())
{
    var roleInitializer = scope.ServiceProvider.GetRequiredService<RoleInitializer>();
    await roleInitializer.InitializeRolesAsync();
}

app.Run();

edited Jul 10, 2024 at 6:58

answered Jul 2, 2024 at 13:22

Jalpa Panchal

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2 Comments

Tomm Over a year ago

InvalidOperationException: Cannot consume scoped service 'Microsoft.AspNetCore.Identity.RoleManager`1[Microsoft.AspNetCore.Identity.IdentityRole]' from singleton 'Microsoft.Extensions.Hosting.IHostedService'.

Jalpa Panchal Over a year ago

@Tomm could you try the updated code. you are getting this error because\ the RoleManager<IdentityRole> is registered with a scoped lifetime, but IHostedService has a singleton lifetime.

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