Send email background service with Hangfire

[tiagosarri]

I'm trying to send emails using Hangfire and Postal, but I'm having problems with the HTTPContext. If I execute the shooting through a controller the sending is done without problems, now if I execute a job via Hangfire an expection is generated.

Code startup.cs

public void ConfigureServices(IServiceCollection services)
{
    services.AddHangfire(configuration => configuration
        .SetDataCompatibilityLevel(CompatibilityLevel.Version_170)
        .UseSimpleAssemblyNameTypeSerializer()
        .UseRecommendedSerializerSettings()
        .UseSqlServerStorage(Configuration.GetConnectionString("default"), new SqlServerStorageOptions
        {
            CommandBatchMaxTimeout = TimeSpan.FromMinutes(5),
            SlidingInvisibilityTimeout = TimeSpan.FromMinutes(5),
            QueuePollInterval = TimeSpan.Zero,
            UseRecommendedIsolationLevel = true,
            UsePageLocksOnDequeue = true,
            DisableGlobalLocks = true
        }));

    services.Configure<EmailSenderOptions>(Configuration.GetSection("EmailSender"));
    services.AddPostal();
    services.AddTransient<IEmailSenderEnhance, EmailSender>();
    services.AddHttpContextAccessor();
    services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
}

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    var options = new DashboardOptions
    {
        Authorization = new[] { new HangFireAuthorizationFilter() }
    };

    app.UseHangfireDashboard("/hangfire", options);
    app.UseHangfireServer();

    RecurringJob.AddOrUpdate<NotificationServices>("SendNotify-", m => m.Notify(1), Cron.Daily);
}

Code NotificationServices.cs

public class NotificationServices
{
    private readonly IEmailSenderEnhance _emailSender;
    private readonly Config _appConfig;
    private readonly IHttpContextAccessor _httpContextAccessor;

    public NotificationServices(IEmailSenderEnhance emailSender, IOptions<Config> optionsAccessor, IHttpContextAccessor httpContextAccessor)
    {
        _emailSender = emailSender;
        if (optionsAccessor == null) throw new ArgumentNullException(nameof(optionsAccessor));
        _appConfig = optionsAccessor.Value;
        _httpContextAccessor = httpContextAccessor;
    }


    public void Notify(int messageId)
    {
        var listOSs = Task.Run(async () => await this.SendEmail(messageId));
    }

    public async Task SendEmail(int orderID)
    {
        var orderRy = new OrderRepository();
        var order = orderRy.Get_By_ID(orderID);

        try
        {
            var requestPath = new Postal.RequestPath
            {
                PathBase = _httpContextAccessor.HttpContext.Request.PathBase.ToString(),
                Host = _httpContextAccessor.HttpContext.Request.Host.ToString(),
                IsHttps = _httpContextAccessor.HttpContext.Request.IsHttps,
                Scheme = _httpContextAccessor.HttpContext.Request.Scheme,
                Method = _httpContextAccessor.HttpContext.Request.Method
            };

            var emailData = new Postal.Email("SendTest")
            {
                RequestPath = requestPath,
            };

            var emailsCopy = $"{order.Salesman.Email},{order.Salesman2.Email},";

            emailData.ViewData["to"] = emailsCopy;
            emailData.ViewData["Order"] = order;

            await _emailSender.SendEmailAsync(emailData);
        }
        catch (Exception ex)
        {
            
        }
    }
}

The error is in HttpContext: _httpContextAccessor.HttpContext.Request.PathBase.ToString()
Object reference not set to an instance of an object

Is it possible to send e-mails via background with Postal?

[hermanho]

There is no HttpContext can be retrieved in background since it is not a http request when Hangfire execute the job. That's why we need the Postal.RequestPath class to create the DefaultHttpContext object in Postal library.

[johanjvr]

@tiagosarri Best way around this is to create the email using Postal and then to serialise it so that hangfire can de-serialise it. Using the smtp client you can then construct a MailMessage which will then allow you to send emails via HangFire.

[DaleCam]

@tiagosarri alternatively simply get what you need out of the httpcontext and pass it as a parameter to the method that creates your email, and use the param instead of the context inside your email. ie:

BackgroundJob.Enqueue(() => SendWelcomeEmail(context.whatever).

public Task SendWelcomeEmail(string username){...send the email in here...}