Problem with Email Sender for verification code .net core 2.1

Question

I've read that usually for this type of error you have only to register the new class on your Startup.cs like this:

services.AddTransient<IEmailSender,MyEmailSender>();

The problem is that i had it implemented even before the error occurred. Here is the raw error and the code:

System.InvalidOperationException: Unable to resolve service for type 'xxxx.Areas.Identity.Services.MyEmailSender' while attempting to activate 'xxxx.Areas.Identity.Pages.Account.RegisterModel'. at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.GetService(IServiceProvider sp, Type type, Type requiredBy, Boolean isDefaultParameterRequired) at lambda_method(Closure , IServiceProvider , Object[] ) at Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure.DefaultPageModelActivatorProvider.<>c__DisplayClass1_0.b__0(PageContext context) at Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure.DefaultPageModelFactoryProvider.<>c__DisplayClass3_0.b__0(PageContext pageContext) at Microsoft.AspNetCore.Mvc.RazorPages.Internal.PageActionInvoker.CreateInstance() at Microsoft.AspNetCore.Mvc.RazorPages.Internal.PageActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted) at Microsoft.AspNetCore.Mvc.RazorPages.Internal.PageActionInvoker.InvokeInnerFilterAsync() at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextResourceFilter() at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResourceExecutedContext context) at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted) at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeFilterPipelineAsync() at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeAsync() at Microsoft.AspNetCore.Builder.RouterMiddleware.Invoke(HttpContext httpContext) at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context) at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context) at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.MigrationsEndPointMiddleware.Invoke(HttpContext context) at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.Invoke(HttpContext httpContext) at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.Invoke(HttpContext httpContext) at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

Now the code:

Startup.cs myemail registration

        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.AddIdentity<ApplicationUser, IdentityRole>(config => {
                config.SignIn.RequireConfirmedEmail = true;
                config.Stores.MaxLengthForKeys = 128; })
               .AddEntityFrameworkStores<ApplicationDbContext>()
               .AddDefaultUI()
               .AddDefaultTokenProviders();

            services.AddTransient<IEmailSender, MyEmailSender>(i =>
                new MyEmailSender(
                    Configuration["EmailSender:Host"],
                    Configuration.GetValue<int>("EmailSender:Port"),
                    Configuration.GetValue<bool>("EmailSender:EnableSSL"),
                    Configuration["EmailSender:UserName"],
                    Configuration["EmailSender:Password"]
                )
            );

            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1).AddControllersAsServices();
        }

Register.cshtml.cs

namespace xxxx.Areas.Identity.Pages.Account
{
    [AllowAnonymous]
    public class RegisterModel : PageModel
    {
        private readonly SignInManager<ApplicationUser> _signInManager;
        private readonly UserManager<ApplicationUser> _userManager;
        private readonly ILogger<RegisterModel> _logger;
        private readonly MyEmailSender _emailSender;

        public RegisterModel(
            UserManager<ApplicationUser> userManager,
            SignInManager<ApplicationUser> signInManager,
            ILogger<RegisterModel> logger,
            MyEmailSender emailSender)
        {
            _userManager = userManager;
            _signInManager = signInManager;
            _logger = logger;
            _emailSender = emailSender;

        }
        [BindProperty]
        public InputModel Input { get; set; }

        public string ReturnUrl { get; set; }

        public class InputModel
        {
            [Required]
            [EmailAddress]
            [Display(Name = "Email")]
            public string Email { get; set; }

            [Required]
            [StringLength(100, ErrorMessage = "The {0} must be at least {2} and at max {1} characters long.", MinimumLength = 6)]
            [DataType(DataType.Password)]
            [Display(Name = "Password")]
            public string Password { get; set; }

            [DataType(DataType.Password)]
            [Display(Name = "Confirm password")]
            [Compare("Password", ErrorMessage = "The password and confirmation password do not match.")]
            public string ConfirmPassword { get; set; }
            [Required]
            [MinLength(4)]
            [Column(TypeName = "Varchar(30)")]
            public string User { get; set; }
            [Required]
            [MinLength(4)]
            [Column(TypeName = "Varchar(30)")]
            public string Name { get; set; }
            [Required]
            [MinLength(4)]
            [Column(TypeName = "Varchar(30)")]
            public string Surname { get; set; }
            public Gender Gender { get; set; }
            public DateTime RegistrationDate { get; set; } = DateTime.Now;
            [DefaultValue(0)]
            public int Coins { get; set; }
            [Required]
            public bool IsAdmin { get; set; }
        }

        public void OnGet(string returnUrl = null)
        {
            ReturnUrl = returnUrl;
        }

        public async Task<IActionResult> OnPostAsync(string returnUrl = null)
        {
            returnUrl = returnUrl ?? Url.Content("~/");
            if (ModelState.IsValid)
            {
                var user = new ApplicationUser { UserName = Input.User, Email = Input.Email, Name = Input.Name,
                    SurName = Input.Surname, Gender = Input.Gender };
                var result = await _userManager.CreateAsync(user, Input.Password);
                if (result.Succeeded)
                {
                    _logger.LogInformation("User created a new account with password.");

                    var code = await _userManager.GenerateEmailConfirmationTokenAsync(user);
                    var callbackUrl = Url.Page(
                        "/Account/ConfirmEmail",
                        pageHandler: null,
                        values: new { userId = user.Id, code = code },
                        protocol: Request.Scheme);

                    StringBuilder VerCode = new StringBuilder();
                    Char[] generator = user.Id.ToCharArray();
                    for (int i = 0; i < 16; i = +4)
                    {
                        VerCode.Append(generator[i]);
                    }
                    var verificationCode = VerCode.ToString();
                    await _emailSender.SendEmailAsync(Input.Email, "Confirm your email",
                        "Your verification code for your registration to Gen/Music is "
                        + verificationCode + " please use this to verify your account!"
                + $"Please write the given code to confirm your account <a href='{HtmlEncoder.Default.Encode(callbackUrl)}'>Click here first!</a>.");

                    await _signInManager.SignInAsync(user, isPersistent: false);
                    return LocalRedirect(returnUrl);
                }
                foreach (var error in result.Errors)
                {
                    ModelState.AddModelError(string.Empty, error.Description);
                }
            }

            // If we got this far, something failed, redisplay form
            return Page();
        }
    }

}

Kirk Larkin Kirk Larkin · Accepted Answer · 2020-01-07T16:43:21

services.AddTransient<IEmailSender, MyEmailSender>();

This line adds IEmailSender to the DI container, which means that any requests for IEmailSender will be satisfied with an instance of MyEmailSender. It states something like "whenever IEmailSender is required, use an instance of MyEmailSender". Note that this does not configure the DI container to satsify direct requests for MyEmailSender.

private readonly MyEmailSender _emailSender;

public RegisterModel(
    UserManager<ApplicationUser> userManager,
    SignInManager<ApplicationUser> signInManager,
    ILogger<RegisterModel> logger,
    MyEmailSender emailSender)
{
    _userManager = userManager;
    _signInManager = signInManager;
    _logger = logger;
    _emailSender = emailSender;
}

This is where the problem lies. Switch out your implementation type for the interface, like this:

private readonly IEmailSender _emailSender;

public RegisterModel(
    UserManager<ApplicationUser> userManager,
    SignInManager<ApplicationUser> signInManager,
    ILogger<RegisterModel> logger,
    IEmailSender emailSender)
{
    _userManager = userManager;
    _signInManager = signInManager;
    _logger = logger;
    _emailSender = emailSender;
}

This will still use your concrete MyEmailSender implementation, as intended.

Problem with Email Sender for verification code .net core 2.1

1 Answers