ASP.NET Core Identity: No service for role manager

Question

I have an ASP.NET Core app that uses Identity. It works, but when I am trying to add custom roles to the database I run into problems.

In Startup ConfigureServices I have added Identity and the role manager as a scoped service like this:

services.AddIdentity<Entities.DB.User, IdentityRole<int>>()
                .AddEntityFrameworkStores<MyDBContext, int>();

services.AddScoped<RoleManager<IdentityRole>>();

and in Startup Configure I inject RoleManager and pass it to my custom class RolesData:

    public void Configure(
        IApplicationBuilder app, 
        IHostingEnvironment env, 
        ILoggerFactory loggerFactory,
        RoleManager<IdentityRole> roleManager
    )
    {

    app.UseIdentity();
    RolesData.SeedRoles(roleManager).Wait();
    app.UseMvc();

This is the RolesData class:

public static class RolesData
{

    private static readonly string[] roles = new[] {
        "role1",
        "role2",
        "role3"
    };

    public static async Task SeedRoles(RoleManager<IdentityRole> roleManager)
    {

        foreach (var role in roles)
        {

            if (!await roleManager.RoleExistsAsync(role))
            {
                var create = await roleManager.CreateAsync(new IdentityRole(role));

                if (!create.Succeeded)
                {

                    throw new Exception("Failed to create role");

                }
            }

        }

    }

}

The app builds without errors, but when trying to access it I get the following error:

Unable to resolve service for type 'Microsoft.AspNetCore.Identity.IRoleStore`1[Microsoft.AspNetCore.Identity.EntityFrameworkCore.IdentityRole]' while attempting to activate 'Microsoft.AspNetCore.Identity.RoleManager

What am I doing wrong? My gut says there's something wrong with how I add the RoleManager as a service.

PS: I have used "No authentication" when creating the project to learn Identity from scratch.

Answer 1

What am I doing wrong? My gut says there's something wrong with how I add the RoleManager as a service.

The registration part is actually fine, tho' you should remove services.AddScoped<RoleManager<IdentityRole>>(), as the role manager is already added for you by services.AddIdentity().

Your issue is most likely caused by a generic type mismatch: while you call services.AddIdentity() with IdentityRole<int>, you try to resolve RoleManager with IdentityRole, which is an equivalent of IdentityRole<string> (string being the default key type in ASP.NET Core Identity).

Update your Configure method to take a RoleManager<IdentityRole<int>> parameter and it should work.