No service for type 'Microsoft.AspNetCore.Iden

问题:

What is the possible cause of this error:

InvalidOperationException: No service for type 'Microsoft.AspNetCore.Identity.UserManager [Microsoft.AspNetCore.Identity.IdentityUser]' has been registered.

My target framework is netcoreapp2.1.

This is my user store class:

public class MyUserStore : IdentityUser
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

And my user role class:

public class MyUserRole : IdentityRole
{
    public string Description { get; set; }
}

My DbContext:

public class ApplicationDbContext : IdentityDbContext<MyUserStore,MyUserRole,string>
{
    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> 
      options): base(options) { }
}

My ConfigureServices method in Startup.cs:

public void ConfigureServices(IServiceCollection services)
{
    services.Configure<CookiePolicyOptions>(options =>
    {
        // This lambda determines whether user consent for non-essential cookies is needed for a given request.
        options.CheckConsentNeeded = context => true;
        options.MinimumSameSitePolicy = SameSiteMode.None;
    });

    services.AddDbContext<ApplicationDbContext>(options =>
        options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

    //services.AddDefaultIdentity<IdentityUser>()
    //    .AddEntityFrameworkStores<ApplicationDbContext>();

    services.AddIdentity<MyUserStore, MyUserRole>(cfg => {
        cfg.User.RequireUniqueEmail = true;
    }).AddEntityFrameworkStores<ApplicationDbContext>();
    services.AddTransient<Seeder>();
    services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}

i want to understand why this is happening and what is the best practice.

回答1:

When registering your own MyUserStore (bad name, should be MyUser) for the AspNetCore Identity, the UserManager<> type will be registered to the ServiceCollection as UserManager<MyUserStore>.

Whenever you want to resolve the UserManager<>, specify the identity user model registered in your startup as the type parameter. Which would be UserManager<MyUserStore> in your specific case.

When calling GetRequiredService<UserManager<IdentityUser>>() on the resulting service provider, GetRequiredService<UserManager<IdentityUser>>() will throw the above exception.

This usually happens in razor views. Eg.

@inject Microsoft.AspNetCore.Identity.UserManager<Microsoft.AspNetCore.Identity.IdentityUser> userManager

Or like-wise, when calling it yourself inside other classes, as may be the case in your Seeder service. Or other code portions. The call stack of your exception should give you a hint of where this is happening.

回答2:

This is the solution, in _LoginPartial.cshtml, replace

@using Microsoft.AspNetCore.Identity
@inject SignInManager<ApplicationUser> SignInManager
@inject UserManager<ApplicationUser> UserManager

with

@using Microsoft.AspNetCore.Identity
@inject SignInManager<MyUserStore> SignInManager
@inject UserManager<MyUserStore> UserManager

Notice the difference, IdentityUser vs MyUserStore

回答3:

Had same issue with core 2. One more area where you need to check is the file _ManageNav.cshtml. Try updating the line

@inject SignInManager<IdentityUser> SignInManager

with

@inject SignInManager<YOURCUSTOMMODEL> SignInManager