我正在尝试使用我的MVC www.example.com应用程序设置SendGridASP.net。这是我第一次使用它。我曾尝试使用SendGrid API密钥进行身份验证，但我不确定是否正确。我已尝试查找SendGrid键的环境变量名称，但我不知道它是什么、在哪里或如何查找，因此无法找到'I don“我在网上似乎找不到任何关于它的信息。我一直收到以下错误：

Value cannot be null.
Parameter name: apiKey
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.ArgumentNullException: Value cannot be null.
Parameter name: apiKey

Source Error:

Line 30:         {
Line 31:             var apiKey = Environment.GetEnvironmentVariable("https://app.sendgrid.com/settings/api_keys/API1");
Line 32:             var client = new SendGridClient(apiKey);
Line 33:             var from = new EmailAddress("test@example.com", "Example User");
Line 34:             var subject = "Sending with SendGrid is Fun";

Source File: C:\Users\M\source\repos\AssessmentTask2\AssessmentTask2\App_Start\IdentityConfig.cs    Line: 32

这是我尝试过的文件的代码，按照一些教程多次更改代码，但我似乎无法修复它
代码：ideintityconfig.cs

using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Security.Claims;
using System.Threading.Tasks;
using System.Web;
using Microsoft.AspNet.Identity;
using Microsoft.AspNet.Identity.EntityFramework;
using Microsoft.AspNet.Identity.Owin;
using Microsoft.Owin;
using Microsoft.Owin.Security;
using AssessmentTask2.Models;
using SendGrid;
using SendGrid.Helpers.Mail;
using System.Configuration;
using System.Diagnostics;
using System.Net;

namespace AssessmentTask2
{
    public class EmailService : IIdentityMessageService
    {
        public async Task SendAsync(IdentityMessage message)
        {
            await configSendGridasync(message);
        }
        //SG.uSDrb4hJQmKPJbTNr_eW2w.lMMbl1c5P8rxdn6cwBr3xdrqXun
        static async Task configSendGridasyn(IdentityMessage message)
        {
            var apiKey = Environment.GetEnvironmentVariable("NAME_OF_THE_ENVIRONMENT_VARIABLE_FOR_YOUR_SENDGRID_KEY");
            var client = new SendGridClient(apiKey);
            var from = new EmailAddress("test@example.com", "Example User");
            var subject = "Sending with SendGrid is Fun";
            var to = new EmailAddress("test@example.com", "Example User");
            var plainTextContent = "and easy to do anywhere, even with C#";
            var htmlContent = "<strong>and easy to do anywhere, even with C#</strong>";
            var msg = MailHelper.CreateSingleEmail(from, to, subject, plainTextContent, htmlContent);
            var response = await client.SendEmailAsync(msg);

            if (client != null)
            {
                await client.SendEmailAsync(msg);
            }
            else
            {
                Trace.TraceError("Failed to create Web transport.");
                await Task.FromResult(0);
            }
        }
    }

    public class SmsService : IIdentityMessageService
    {
        public Task SendAsync(IdentityMessage message)
        {
            // Plug in your SMS service here to send a text message.
            return Task.FromResult(0);
        }
    }

    // Configure the application user manager used in this application. UserManager is defined in ASP.NET Identity and is used by the application.
    public class ApplicationUserManager : UserManager<ApplicationUser>
    {
        public ApplicationUserManager(IUserStore<ApplicationUser> store)
            : base(store)
        {
        }

        public static ApplicationUserManager Create(IdentityFactoryOptions<ApplicationUserManager> options, IOwinContext context) 
        {
            var manager = new ApplicationUserManager(new UserStore<ApplicationUser>(context.Get<ApplicationDbContext>()));
            // Configure validation logic for usernames
            manager.UserValidator = new UserValidator<ApplicationUser>(manager)
            {
                AllowOnlyAlphanumericUserNames = false,
                RequireUniqueEmail = true
            };

            // Configure validation logic for passwords
            manager.PasswordValidator = new PasswordValidator
            {
                RequiredLength = 6,
                RequireNonLetterOrDigit = true,
                RequireDigit = true,
                RequireLowercase = true,
                RequireUppercase = true,
            };

            // Configure user lockout defaults
            manager.UserLockoutEnabledByDefault = true;
            manager.DefaultAccountLockoutTimeSpan = TimeSpan.FromMinutes(5);
            manager.MaxFailedAccessAttemptsBeforeLockout = 5;

            // Register two factor authentication providers. This application uses Phone and Emails as a step of receiving a code for verifying the user
            // You can write your own provider and plug it in here.
            manager.RegisterTwoFactorProvider("Phone Code", new PhoneNumberTokenProvider<ApplicationUser>
            {
                MessageFormat = "Your security code is {0}"
            });
            manager.RegisterTwoFactorProvider("Email Code", new EmailTokenProvider<ApplicationUser>
            {
                Subject = "Security Code",
                BodyFormat = "Your security code is {0}"
            });
            manager.EmailService = new EmailService();
            manager.SmsService = new SmsService();
            var dataProtectionProvider = options.DataProtectionProvider;
            if (dataProtectionProvider != null)
            {
                manager.UserTokenProvider = 
                    new DataProtectorTokenProvider<ApplicationUser>(dataProtectionProvider.Create("ASP.NET Identity"));
            }
            return manager;
        }
    }

    // Configure the application sign-in manager which is used in this application.
    public class ApplicationSignInManager : SignInManager<ApplicationUser, string>
    {
        public ApplicationSignInManager(ApplicationUserManager userManager, IAuthenticationManager authenticationManager)
            : base(userManager, authenticationManager)
        {
        }

        public override Task<ClaimsIdentity> CreateUserIdentityAsync(ApplicationUser user)
        {
            return user.GenerateUserIdentityAsync((ApplicationUserManager)UserManager);
        }

        public static ApplicationSignInManager Create(IdentityFactoryOptions<ApplicationSignInManager> options, IOwinContext context)
        {
            return new ApplicationSignInManager(context.GetUserManager<ApplicationUserManager>(), context.Authentication);
        }
    }
}